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acrac_3094113_20

Pulmonary Arteriovenous Malformation PAVM

CTPA provides similar diagnostic accuracy as noncontrast CT due to the high natural contrast inherent to pulmonary anatomy. IV contrast material administration adds a small risk of air embolism in patients with PAVM. Adequate precaution should be taken to prevent air [27]. Correlating the PAVM grade with contrast-enhanced echo has been shown to be more sensitive with CTPA compared to noncontrast CT [31]. Strategies to mitigate the artifacts from embolic material by adjusting scan parameters and using dual-energy and spectral CT acquisition have shown promise in other anatomical locations. For instance, Zheng et al [54] showed Pulmonary Arteriovenous Malformation (PAVM) that spectral CT using metal artifact reduction software improved vascular evaluation of adjacent metallic coils in the brain. Visualization of recanalized flow remains a challenge in posttreatment CT evaluation for reperfusion. MRA Chest Without and With IV Contrast There is no role for the routine use of MRA chest without and with IV contrast in the workup of a patient with treated PAVM. MRA Chest Without IV Contrast There is no role for the routine use of MRA chest without IV contrast in the workup of a patient with treated PAVM. MRA Pulmonary Arteries Without and With IV Contrast Dynamic MRA using time-resolved sequences has the advantage over CT, and it is not affected by the artifact from the embolic material. Time-resolved MRA can detect flow in the pulmonary vein similar to pulmonary arteriography. Shimohira et al [55] compared the sensitivity and specificity of CT and time-resolved MRA with digital subtraction angiography as a reference standard in a multi-institutional retrospective cohort of 205 patients. Using 55% as the threshold reduction of the sac diameter on CT, they found a sensitivity and specificity for CT at 82% and 81%, respectively. Time-resolved MRA on the other hand has a sensitivity and specificity of 89% and 95%, respectively.

Pulmonary Arteriovenous Malformation PAVM . CTPA provides similar diagnostic accuracy as noncontrast CT due to the high natural contrast inherent to pulmonary anatomy. IV contrast material administration adds a small risk of air embolism in patients with PAVM. Adequate precaution should be taken to prevent air [27]. Correlating the PAVM grade with contrast-enhanced echo has been shown to be more sensitive with CTPA compared to noncontrast CT [31]. Strategies to mitigate the artifacts from embolic material by adjusting scan parameters and using dual-energy and spectral CT acquisition have shown promise in other anatomical locations. For instance, Zheng et al [54] showed Pulmonary Arteriovenous Malformation (PAVM) that spectral CT using metal artifact reduction software improved vascular evaluation of adjacent metallic coils in the brain. Visualization of recanalized flow remains a challenge in posttreatment CT evaluation for reperfusion. MRA Chest Without and With IV Contrast There is no role for the routine use of MRA chest without and with IV contrast in the workup of a patient with treated PAVM. MRA Chest Without IV Contrast There is no role for the routine use of MRA chest without IV contrast in the workup of a patient with treated PAVM. MRA Pulmonary Arteries Without and With IV Contrast Dynamic MRA using time-resolved sequences has the advantage over CT, and it is not affected by the artifact from the embolic material. Time-resolved MRA can detect flow in the pulmonary vein similar to pulmonary arteriography. Shimohira et al [55] compared the sensitivity and specificity of CT and time-resolved MRA with digital subtraction angiography as a reference standard in a multi-institutional retrospective cohort of 205 patients. Using 55% as the threshold reduction of the sac diameter on CT, they found a sensitivity and specificity for CT at 82% and 81%, respectively. Time-resolved MRA on the other hand has a sensitivity and specificity of 89% and 95%, respectively.

3094113

acrac_3094113_21

Pulmonary Arteriovenous Malformation PAVM

Similar findings have been reported in 28 PAVMs in 10 patients by Kawai et al [56]. In a recent study, Hong et al [57] studied the feasibility of time-resolved MRA in evaluating the feeding arteries and reperfusion after embolization of PAVMs in 9 patients with 62 PAVMs. They found a sensitivity and specificity of 100% for detection of reperfusion compared to catheter angiography as the reference standard. The visibility of the feeding arteries was compared to CT, and they found good correlation between 0.76 and 0.79 with 2 readers when using 3- D maximum intensity projection images. Time-resolved MRA also has the advantage of detecting reperfusion after repeat embolization for persistence as the burden of coiling will be greater leading to more metallic artifacts on CT [58]. MRA Pulmonary Arteries Without IV Contrast There is no role for the routine use of MRA pulmonary angiography without IV contrast in the workup of a patient with treated PAVM. Radiography Chest The radiographic appearance of a lower lobe pulmonary nodule with a branching afferent artery and dilated efferent vein defines the classical appearance of PAVM on chest radiography. The sensitivity of chest radiography is 60% to 70% with a 98% specificity when the classical findings are present [36]. The afferent and efferent vasculature and smaller PAVMs may be difficult to see on a single-view chest radiograph. Best diagnostic results are obtained when a 2-view chest radiograph, posteroanterior view, and lateral view is performed [37]. Chest radiography has limited usefulness to detect recurrent disease in the setting of prior treated PAVM. US Echocardiography Transesophageal There is no role for TEE as a standalone diagnostic tool in the evaluation of PAVMs. The usefulness of TEE in the context of PAVM is to rule out intracardiac shunts [38]. Its ability to demonstrate the interatrial septum and the insertion of the pulmonary veins into the left atrium is useful to evaluate the anatomical variations [39].

Pulmonary Arteriovenous Malformation PAVM . Similar findings have been reported in 28 PAVMs in 10 patients by Kawai et al [56]. In a recent study, Hong et al [57] studied the feasibility of time-resolved MRA in evaluating the feeding arteries and reperfusion after embolization of PAVMs in 9 patients with 62 PAVMs. They found a sensitivity and specificity of 100% for detection of reperfusion compared to catheter angiography as the reference standard. The visibility of the feeding arteries was compared to CT, and they found good correlation between 0.76 and 0.79 with 2 readers when using 3- D maximum intensity projection images. Time-resolved MRA also has the advantage of detecting reperfusion after repeat embolization for persistence as the burden of coiling will be greater leading to more metallic artifacts on CT [58]. MRA Pulmonary Arteries Without IV Contrast There is no role for the routine use of MRA pulmonary angiography without IV contrast in the workup of a patient with treated PAVM. Radiography Chest The radiographic appearance of a lower lobe pulmonary nodule with a branching afferent artery and dilated efferent vein defines the classical appearance of PAVM on chest radiography. The sensitivity of chest radiography is 60% to 70% with a 98% specificity when the classical findings are present [36]. The afferent and efferent vasculature and smaller PAVMs may be difficult to see on a single-view chest radiograph. Best diagnostic results are obtained when a 2-view chest radiograph, posteroanterior view, and lateral view is performed [37]. Chest radiography has limited usefulness to detect recurrent disease in the setting of prior treated PAVM. US Echocardiography Transesophageal There is no role for TEE as a standalone diagnostic tool in the evaluation of PAVMs. The usefulness of TEE in the context of PAVM is to rule out intracardiac shunts [38]. Its ability to demonstrate the interatrial septum and the insertion of the pulmonary veins into the left atrium is useful to evaluate the anatomical variations [39].

3094113

acrac_3094113_22

Pulmonary Arteriovenous Malformation PAVM

US Echocardiography Transesophageal With IV Contrast TEE with IV agitated saline contrast material is not routinely used to diagnose PAVM. Contrast-enhanced TEE maybe helpful to locate a PAVM based on the excellent visualization of the 4 pulmonary venous ostia as veins drain into the left atrium. Based on the visualization of contrast material emanating from a particular pulmonary vein, the location of the PAVM in that venous territory can be confirmed [38,40]. In the presence of multiple PAVMs, the usefulness of this imaging modality in identifying the location of the PAVMs may be limited. US Echocardiography Transthoracic Resting There is no role for TTE in the resting phase for evaluation of PAVM. It does allow evaluation of intracardiac shunts and assessment of cardiac function [38]. US Echocardiography Transthoracic With IV Contrast TTCE is an essential diagnostic test for patients suspected of having a PAVM. TTCE with agitated saline has a 98% to 99% sensitivity and a 67% to 91% specificity for detecting PAVMs [41]. The microbubbles are visualized after 3 to 8 cardiac cycles in the left atrium after initial opacification of the right chambers in patients with an intrapulmonary shunt [1]. TTCE does not provide any information regarding the size and location of the PAVM. Based on the appearance of the bubbles in the left atrium a semiquantitative grading system has been developed Pulmonary Arteriovenous Malformation (PAVM) [42,43]. The grades are defined as 0 with no opacification, grade 1 with <30 bubbles, grade 2 with moderate filling, and grade 3 with complete opacification of the left atrium. The grading system correlates well with the diagnosis of PAVM, with higher grades associated with larger shunts and cerebral complications [41,44,45]. Usefulness of the grading system to predict treatment of PAVM demonstrates that grades 2 and 3 have a positive predictive value of 0.21 (95% CI, 0.05-0.36) and 0.87 (95% CI, 0.79-0.99), respectively [44].

Pulmonary Arteriovenous Malformation PAVM . US Echocardiography Transesophageal With IV Contrast TEE with IV agitated saline contrast material is not routinely used to diagnose PAVM. Contrast-enhanced TEE maybe helpful to locate a PAVM based on the excellent visualization of the 4 pulmonary venous ostia as veins drain into the left atrium. Based on the visualization of contrast material emanating from a particular pulmonary vein, the location of the PAVM in that venous territory can be confirmed [38,40]. In the presence of multiple PAVMs, the usefulness of this imaging modality in identifying the location of the PAVMs may be limited. US Echocardiography Transthoracic Resting There is no role for TTE in the resting phase for evaluation of PAVM. It does allow evaluation of intracardiac shunts and assessment of cardiac function [38]. US Echocardiography Transthoracic With IV Contrast TTCE is an essential diagnostic test for patients suspected of having a PAVM. TTCE with agitated saline has a 98% to 99% sensitivity and a 67% to 91% specificity for detecting PAVMs [41]. The microbubbles are visualized after 3 to 8 cardiac cycles in the left atrium after initial opacification of the right chambers in patients with an intrapulmonary shunt [1]. TTCE does not provide any information regarding the size and location of the PAVM. Based on the appearance of the bubbles in the left atrium a semiquantitative grading system has been developed Pulmonary Arteriovenous Malformation (PAVM) [42,43]. The grades are defined as 0 with no opacification, grade 1 with <30 bubbles, grade 2 with moderate filling, and grade 3 with complete opacification of the left atrium. The grading system correlates well with the diagnosis of PAVM, with higher grades associated with larger shunts and cerebral complications [41,44,45]. Usefulness of the grading system to predict treatment of PAVM demonstrates that grades 2 and 3 have a positive predictive value of 0.21 (95% CI, 0.05-0.36) and 0.87 (95% CI, 0.79-0.99), respectively [44].

3094113

acrac_3094113_23

Pulmonary Arteriovenous Malformation PAVM

Adverse events including air embolism are rare with TTCE occurring in <1% [46]. However, as a tool to measure the effectiveness of prior treatment, TTCE has low specificity and sensitivity. Variant 5: Asymptomatic with abnormal imaging on CT or chest radiography suggestive of PAVM. Next imaging study. Arteriography Pulmonary The real-time nature of pulmonary arteriography allows for high accuracy in delineating the angioarchitecture and detection of flow characteristics such as the early draining vein. In a study comparing the specificity of pulmonary arteriography and CTA, pulmonary arteriography was noted to have a higher specificity for detecting the angioarchitecture compared to CTA (100% versus 78%) [24]. Pulmonary angiography is performed as a part of the treatment procedure and does not have a standalone diagnostic role in detecting PAVM. An exception where pulmonary angiogram would be helpful as an initial diagnostic imaging tool is in a patient who is hemodynamically unstable with clinical suspicion of pulmonary hemorrhage from a PAVM [25]. CT Chest With IV Contrast Contrast-enhanced CT chest offers high spatial resolution and can detect the number, size, and distribution of PAVMs accurately. Contrast-enhanced CT provides similar diagnostic accuracy as noncontrast CT due to the high natural contrast inherent to pulmonary anatomy. IV contrast material administration adds a small risk of air embolism in patients with PAVM. Adequate precaution should be taken to prevent air embolism [10,26]. Cross- sectional anatomy displayed on CT chest with IV contrast is useful in treatment planning [10,27]. CT Chest Without and With IV Contrast There is limited data to support obtaining a CT chest with and without IV contrast in the setting of suspected PAVM.

Pulmonary Arteriovenous Malformation PAVM . Adverse events including air embolism are rare with TTCE occurring in <1% [46]. However, as a tool to measure the effectiveness of prior treatment, TTCE has low specificity and sensitivity. Variant 5: Asymptomatic with abnormal imaging on CT or chest radiography suggestive of PAVM. Next imaging study. Arteriography Pulmonary The real-time nature of pulmonary arteriography allows for high accuracy in delineating the angioarchitecture and detection of flow characteristics such as the early draining vein. In a study comparing the specificity of pulmonary arteriography and CTA, pulmonary arteriography was noted to have a higher specificity for detecting the angioarchitecture compared to CTA (100% versus 78%) [24]. Pulmonary angiography is performed as a part of the treatment procedure and does not have a standalone diagnostic role in detecting PAVM. An exception where pulmonary angiogram would be helpful as an initial diagnostic imaging tool is in a patient who is hemodynamically unstable with clinical suspicion of pulmonary hemorrhage from a PAVM [25]. CT Chest With IV Contrast Contrast-enhanced CT chest offers high spatial resolution and can detect the number, size, and distribution of PAVMs accurately. Contrast-enhanced CT provides similar diagnostic accuracy as noncontrast CT due to the high natural contrast inherent to pulmonary anatomy. IV contrast material administration adds a small risk of air embolism in patients with PAVM. Adequate precaution should be taken to prevent air embolism [10,26]. Cross- sectional anatomy displayed on CT chest with IV contrast is useful in treatment planning [10,27]. CT Chest Without and With IV Contrast There is limited data to support obtaining a CT chest with and without IV contrast in the setting of suspected PAVM.

3094113

acrac_3094113_24

Pulmonary Arteriovenous Malformation PAVM

A study by Nawaz et al [24] compared CT with and without IV contrast to DSA for assessment of PAVMs. Their study showed superior sensitivity of CT compared to DSA for detection of PAVM; however, the specificity for CT was inferior to that of DSA. Cross-sectional anatomy displayed on CT chest with IV contrast is useful in treatment planning [10,27]. The benefit of using CT chest without and with IV contrast for assessing PAVM compared to stand-alone CT without IV contrast or CT with IV contrast is unclear [24]. CT Chest Without IV Contrast Noncontrast chest CT scan is helpful in confirming the diagnosis of PAVM. Like CT chest with IV contrast, Noncontrast CT offers high spatial resolution and can detect the number, size, and distribution of PAVMs accurately. Remy et al [28] were able to predict angioarchitecture of the PAVMs in 95% of cases using noncontrast CT and 3-D reconstruction. Cross-sectional anatomy displayed on CT chest without IV contrast is useful in treatment planning [10,27]. CTA Chest With IV Contrast CTA chest also provides similar diagnostic accuracy as noncontrast CT due to the high natural contrast inherent to pulmonary anatomy. IV contrast material administration adds a small risk of air embolism in patients with PAVM. Adequate precaution should be taken to prevent air embolism. Unlike CTPA, the vascular enhancement during CTA is timed for the aorta and its branches, and, thus, it may help identify systemic supply to PAVMs via the systemic arteries [10,29,30]. Cross-sectional anatomy displayed on CT chest with IV contrast is useful in treatment planning [10,27]. CTA Pulmonary Arteries With IV Contrast CTPA specifically assesses the pulmonary vasculature. IV contrast material is timed for optimum evaluation of the pulmonary arteries. Use of CTPA for evaluation of PAVM is used in clinical practice when considering a contrast- enhanced CT scan for evaluating PAVM.

Pulmonary Arteriovenous Malformation PAVM . A study by Nawaz et al [24] compared CT with and without IV contrast to DSA for assessment of PAVMs. Their study showed superior sensitivity of CT compared to DSA for detection of PAVM; however, the specificity for CT was inferior to that of DSA. Cross-sectional anatomy displayed on CT chest with IV contrast is useful in treatment planning [10,27]. The benefit of using CT chest without and with IV contrast for assessing PAVM compared to stand-alone CT without IV contrast or CT with IV contrast is unclear [24]. CT Chest Without IV Contrast Noncontrast chest CT scan is helpful in confirming the diagnosis of PAVM. Like CT chest with IV contrast, Noncontrast CT offers high spatial resolution and can detect the number, size, and distribution of PAVMs accurately. Remy et al [28] were able to predict angioarchitecture of the PAVMs in 95% of cases using noncontrast CT and 3-D reconstruction. Cross-sectional anatomy displayed on CT chest without IV contrast is useful in treatment planning [10,27]. CTA Chest With IV Contrast CTA chest also provides similar diagnostic accuracy as noncontrast CT due to the high natural contrast inherent to pulmonary anatomy. IV contrast material administration adds a small risk of air embolism in patients with PAVM. Adequate precaution should be taken to prevent air embolism. Unlike CTPA, the vascular enhancement during CTA is timed for the aorta and its branches, and, thus, it may help identify systemic supply to PAVMs via the systemic arteries [10,29,30]. Cross-sectional anatomy displayed on CT chest with IV contrast is useful in treatment planning [10,27]. CTA Pulmonary Arteries With IV Contrast CTPA specifically assesses the pulmonary vasculature. IV contrast material is timed for optimum evaluation of the pulmonary arteries. Use of CTPA for evaluation of PAVM is used in clinical practice when considering a contrast- enhanced CT scan for evaluating PAVM.

3094113

acrac_3094113_25

Pulmonary Arteriovenous Malformation PAVM

Like other CT techniques, CTPA offers high special resolution and can detect the number, size, and distribution of PAVMs accurately. CTPA provides similar diagnostic accuracy as noncontrast CT due to the high natural contrast inherent to pulmonary anatomy. IV contrast material administration adds a small risk of air embolism in patients with PAVM. Adequate precaution should be taken to prevent air [27]. Correlating the PAVM grade with contrast-enhanced echo has been shown to be more sensitive with CTPA Pulmonary Arteriovenous Malformation (PAVM) compared to noncontrast CT [31]. Cross-sectional anatomy displayed on CT chest with IV contrast is useful in treatment planning [10,27]. MRA Chest Without and With IV Contrast There is no role for the routine use of MRA chest without and with IV contrast in the workup of a patient suspected of a PAVM. MRA Chest Without IV Contrast There is no role for the routine use of MRA chest without IV contrast in the workup of a patient suspected of a PAVM. MRA Pulmonary Arteries Without and With IV Contrast Contrast-enhanced MRA pulmonary arteries provides anatomical information about the presence, number, size, and location of PAVMs. Schneider et al [32] evaluated 203 patients with HHT or first-degree relatives with HHT using contrast-enhanced MRA. Patients with definite and uncertain diagnosis of PAVM on MRA underwent pulmonary angiogram. Pulmonary angiogram detected only 77% to 80% of the PAVMs that were seen on MRA. In their study, the majority of the PAVMs not detected by pulmonary angiogram were <5 mm in size. The size criterion was defined as the size of the PAVM itself and not of the feeding artery. A more recent study by Van den Heuvel et al [33] investigated the sensitivity of contrast-enhanced MRA for detection of PAVMs with a feeding artery >2 cm in children and young adults.

Pulmonary Arteriovenous Malformation PAVM . Like other CT techniques, CTPA offers high special resolution and can detect the number, size, and distribution of PAVMs accurately. CTPA provides similar diagnostic accuracy as noncontrast CT due to the high natural contrast inherent to pulmonary anatomy. IV contrast material administration adds a small risk of air embolism in patients with PAVM. Adequate precaution should be taken to prevent air [27]. Correlating the PAVM grade with contrast-enhanced echo has been shown to be more sensitive with CTPA Pulmonary Arteriovenous Malformation (PAVM) compared to noncontrast CT [31]. Cross-sectional anatomy displayed on CT chest with IV contrast is useful in treatment planning [10,27]. MRA Chest Without and With IV Contrast There is no role for the routine use of MRA chest without and with IV contrast in the workup of a patient suspected of a PAVM. MRA Chest Without IV Contrast There is no role for the routine use of MRA chest without IV contrast in the workup of a patient suspected of a PAVM. MRA Pulmonary Arteries Without and With IV Contrast Contrast-enhanced MRA pulmonary arteries provides anatomical information about the presence, number, size, and location of PAVMs. Schneider et al [32] evaluated 203 patients with HHT or first-degree relatives with HHT using contrast-enhanced MRA. Patients with definite and uncertain diagnosis of PAVM on MRA underwent pulmonary angiogram. Pulmonary angiogram detected only 77% to 80% of the PAVMs that were seen on MRA. In their study, the majority of the PAVMs not detected by pulmonary angiogram were <5 mm in size. The size criterion was defined as the size of the PAVM itself and not of the feeding artery. A more recent study by Van den Heuvel et al [33] investigated the sensitivity of contrast-enhanced MRA for detection of PAVMs with a feeding artery >2 cm in children and young adults.

3094113

acrac_3094113_26

Pulmonary Arteriovenous Malformation PAVM

They enrolled 53 patients who had a TTCE grade 2 or 3 who underwent chest CT and were found to have the PAVM with a feeding artery >2 cm to receive a contrast-enhanced MRA. The sensitivity of contrast-enhanced MRA to detect PAVMs with a feeding artery size of >2cm was 92%, and the specificity ranged from 67% to 96%. MRA Pulmonary Arteries Without IV Contrast There is no role for the routine use of MRA pulmonary angiography without IV contrast in the workup of a patient suspected of a PAVM. US Echocardiography Transesophageal There is no role for TEE as a standalone diagnostic tool in the evaluation of PAVMs. The usefulness of TEE in the context of PAVM is to rule out intracardiac shunts [38]. Its ability to demonstrate the interatrial septum and the insertion of the pulmonary veins into the left atrium is useful to evaluate the anatomical variations [39]. US Echocardiography Transesophageal With IV Contrast TEE with IV agitated saline contrast material is not routinely used to diagnose PAVM. Contrast-enhanced TEE maybe helpful to locate a PAVM based on the excellent visualization of the 4 pulmonary venous ostia as veins drain into the left atrium. Based on the visualization of contrast material emanating from a particular pulmonary vein, the location of the PAVM in that venous territory can be confirmed [38,40]. In the presence of multiple PAVMs, the usefulness of this imaging modality in identifying the location of the PAVMs may be limited. US Echocardiography Transthoracic Resting There is no role for TTE in the resting phase for the evaluation of PAVM. It does allow evaluation of intracardiac shunts and assessment of cardiac function [38]. Pulmonary Arteriovenous Malformation (PAVM) Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.

Pulmonary Arteriovenous Malformation PAVM . They enrolled 53 patients who had a TTCE grade 2 or 3 who underwent chest CT and were found to have the PAVM with a feeding artery >2 cm to receive a contrast-enhanced MRA. The sensitivity of contrast-enhanced MRA to detect PAVMs with a feeding artery size of >2cm was 92%, and the specificity ranged from 67% to 96%. MRA Pulmonary Arteries Without IV Contrast There is no role for the routine use of MRA pulmonary angiography without IV contrast in the workup of a patient suspected of a PAVM. US Echocardiography Transesophageal There is no role for TEE as a standalone diagnostic tool in the evaluation of PAVMs. The usefulness of TEE in the context of PAVM is to rule out intracardiac shunts [38]. Its ability to demonstrate the interatrial septum and the insertion of the pulmonary veins into the left atrium is useful to evaluate the anatomical variations [39]. US Echocardiography Transesophageal With IV Contrast TEE with IV agitated saline contrast material is not routinely used to diagnose PAVM. Contrast-enhanced TEE maybe helpful to locate a PAVM based on the excellent visualization of the 4 pulmonary venous ostia as veins drain into the left atrium. Based on the visualization of contrast material emanating from a particular pulmonary vein, the location of the PAVM in that venous territory can be confirmed [38,40]. In the presence of multiple PAVMs, the usefulness of this imaging modality in identifying the location of the PAVMs may be limited. US Echocardiography Transthoracic Resting There is no role for TTE in the resting phase for the evaluation of PAVM. It does allow evaluation of intracardiac shunts and assessment of cardiac function [38]. Pulmonary Arteriovenous Malformation (PAVM) Supporting Documents The evidence table, literature search, and appendix for this topic are available at https://acsearch. acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.

3094113

acrac_3082587_0

Acute Hip Pain Suspected Fracture PCAs

Introduction/Background Fractures of the proximal femur (commonly referred to as hip fractures) are a frequent source of morbidity and mortality in elderly osteoporotic patients [1]. Typically the result of a ground-level fall, fractures of this type result in approximately 300,000 hospitalizations per year and are nearly twice as common in women as in men [2,3]. As the United States population continues to age, the incidence of hip fractures and associated medical costs will continue to rise, predicted to reach $18 billion by 2025 [4]. Patients suffer a substantial decline in quality of life following a hip fracture [5] as well as a 1-year mortality rate of 22% for women and 33% for men [1]. Delays in diagnosis and treatment are associated with increased cost, complication rate, length of hospital stay, and short- and long-term mortality [6-13]. Therefore, rapid diagnosis and treatment of hip fractures is critical. Hip fractures cannot be reliably diagnosed or excluded on the basis of physical examination alone; therefore, imaging plays a key role in early and accurate diagnosis [14]. Treatment for both intra- and extracapsular proximal femoral fractures in the elderly is typically surgical fixation because of the risk of further fracture displacement and the dangers of prolonged immobilization in the elderly [15]. Joint replacement may be performed for displaced fractures of the femoral neck where the risk of femoral head avascular necrosis is high. Fractures from high-force trauma are also commonly treated with surgical fixation for stability to reduce the risk of post-traumatic osteoarthritis. Reprint requests to: [email protected] Acute Hip Pain-Suspected Fracture Multiple studies have demonstrated that radiographs have limited sensitivity for fracture detection of the proximal femur, particularly in elderly osteoporotic patients [20-24].

Acute Hip Pain Suspected Fracture PCAs. Introduction/Background Fractures of the proximal femur (commonly referred to as hip fractures) are a frequent source of morbidity and mortality in elderly osteoporotic patients [1]. Typically the result of a ground-level fall, fractures of this type result in approximately 300,000 hospitalizations per year and are nearly twice as common in women as in men [2,3]. As the United States population continues to age, the incidence of hip fractures and associated medical costs will continue to rise, predicted to reach $18 billion by 2025 [4]. Patients suffer a substantial decline in quality of life following a hip fracture [5] as well as a 1-year mortality rate of 22% for women and 33% for men [1]. Delays in diagnosis and treatment are associated with increased cost, complication rate, length of hospital stay, and short- and long-term mortality [6-13]. Therefore, rapid diagnosis and treatment of hip fractures is critical. Hip fractures cannot be reliably diagnosed or excluded on the basis of physical examination alone; therefore, imaging plays a key role in early and accurate diagnosis [14]. Treatment for both intra- and extracapsular proximal femoral fractures in the elderly is typically surgical fixation because of the risk of further fracture displacement and the dangers of prolonged immobilization in the elderly [15]. Joint replacement may be performed for displaced fractures of the femoral neck where the risk of femoral head avascular necrosis is high. Fractures from high-force trauma are also commonly treated with surgical fixation for stability to reduce the risk of post-traumatic osteoarthritis. Reprint requests to: [email protected] Acute Hip Pain-Suspected Fracture Multiple studies have demonstrated that radiographs have limited sensitivity for fracture detection of the proximal femur, particularly in elderly osteoporotic patients [20-24].

3082587

acrac_3082587_1

Acute Hip Pain Suspected Fracture PCAs

All of these studies constitute retrospective series in which patients with negative radiographs but high clinical suspicion went on to receive a MRI scan at the discretion of the evaluating clinician. In one such study, 14% of patients with negative radiographs were found to have fractures of the hip or pelvis [23]. In this same study, Kirby et al [23] also reported 12% of patients with suspicious radiographs were found to have no fracture on MRI, illustrating limitations in the specificity of radiographs as well. Other studies have had more dramatic results, with Sankey et al [25] reporting 83 of 98 patients to have fractures after negative radiographs, 23 of whom required operative management. The variability is likely due to differing proportions of patients going on to MRI following negative radiographs in these retrospective studies. However, there is no accepted clinical decision rule to guide when patients with suspected hip fracture should have advanced imaging after negative radiographs. A new inability to bear weight is a clinically suspicious finding, although the sensitivity and specificity of this is unknown [20]. Allowing for variation between studies, the estimated prevalence of occult fracture after negative radiographs has been estimated at 4% to 10%, indicating the inability of negative radiographs alone to exclude fracture [21,26]. Risk factors for radiographically occult fracture in these studies included those age >65, low-force trauma, such as a ground-level fall, and female gender. These studies have almost exclusively included elderly patients. There is no relevant literature regarding the sensitivity and specificity of radiographs in the younger patient population, and clinicians are suggested to proceed with caution. Radiography Pelvis There is no specific literature regarding the use of an AP view of the pelvis alone for acute hip pain following low-force trauma.

Acute Hip Pain Suspected Fracture PCAs. All of these studies constitute retrospective series in which patients with negative radiographs but high clinical suspicion went on to receive a MRI scan at the discretion of the evaluating clinician. In one such study, 14% of patients with negative radiographs were found to have fractures of the hip or pelvis [23]. In this same study, Kirby et al [23] also reported 12% of patients with suspicious radiographs were found to have no fracture on MRI, illustrating limitations in the specificity of radiographs as well. Other studies have had more dramatic results, with Sankey et al [25] reporting 83 of 98 patients to have fractures after negative radiographs, 23 of whom required operative management. The variability is likely due to differing proportions of patients going on to MRI following negative radiographs in these retrospective studies. However, there is no accepted clinical decision rule to guide when patients with suspected hip fracture should have advanced imaging after negative radiographs. A new inability to bear weight is a clinically suspicious finding, although the sensitivity and specificity of this is unknown [20]. Allowing for variation between studies, the estimated prevalence of occult fracture after negative radiographs has been estimated at 4% to 10%, indicating the inability of negative radiographs alone to exclude fracture [21,26]. Risk factors for radiographically occult fracture in these studies included those age >65, low-force trauma, such as a ground-level fall, and female gender. These studies have almost exclusively included elderly patients. There is no relevant literature regarding the sensitivity and specificity of radiographs in the younger patient population, and clinicians are suggested to proceed with caution. Radiography Pelvis There is no specific literature regarding the use of an AP view of the pelvis alone for acute hip pain following low-force trauma.

3082587

acrac_3082587_2

Acute Hip Pain Suspected Fracture PCAs

Previous literature regarding the accuracy of radiography has almost exclusively evaluated AP and cross-table lateral radiographs of the hip or the combined use of AP pelvis and hip radiographs. However, it is well established that patients with clinically suspected proximal femur fracture often have fractures of the pelvis, including the sacrum and pubic rami [21,27-30]. Therefore, it has been recommended that the radiographic series include the AP view of the pelvis along with the orthogonal views of the symptomatic hip [31]. The inclusion of a pelvis radiograph also allows for comparison of potential abnormalities to the contralateral asymptomatic side. Pelvis radiographs share the same limitations in sensitivity and specificity for fracture detection as hip radiographs, and a negative radiograph alone cannot exclude fracture. Radiography Pelvis and Hip As previously discussed, patients with clinically suspected proximal femur fracture often have fractures of the pelvis that include the sacrum and pubic rami [21,27-30]. Moreover, these pelvic fractures may occur in isolation or concomitant with a fracture of the proximal femur [28]. Therefore, it has been recommended that the radiographic series include both the AP view of the pelvis along with orthogonal views of the symptomatic hip [31]. The inclusion of a pelvis radiograph also allows for comparison of potential abnormalities to the contralateral asymptomatic side. For these reasons, an AP view of the pelvis with a cross-table lateral view of the symptomatic hip is the standard approach at many institutions, whereas some will include three views: an AP view of the pelvis, a separate AP view of the symptomatic hip, and the cross-table lateral view. There is no specific literature to compare these two approaches.

Acute Hip Pain Suspected Fracture PCAs. Previous literature regarding the accuracy of radiography has almost exclusively evaluated AP and cross-table lateral radiographs of the hip or the combined use of AP pelvis and hip radiographs. However, it is well established that patients with clinically suspected proximal femur fracture often have fractures of the pelvis, including the sacrum and pubic rami [21,27-30]. Therefore, it has been recommended that the radiographic series include the AP view of the pelvis along with the orthogonal views of the symptomatic hip [31]. The inclusion of a pelvis radiograph also allows for comparison of potential abnormalities to the contralateral asymptomatic side. Pelvis radiographs share the same limitations in sensitivity and specificity for fracture detection as hip radiographs, and a negative radiograph alone cannot exclude fracture. Radiography Pelvis and Hip As previously discussed, patients with clinically suspected proximal femur fracture often have fractures of the pelvis that include the sacrum and pubic rami [21,27-30]. Moreover, these pelvic fractures may occur in isolation or concomitant with a fracture of the proximal femur [28]. Therefore, it has been recommended that the radiographic series include both the AP view of the pelvis along with orthogonal views of the symptomatic hip [31]. The inclusion of a pelvis radiograph also allows for comparison of potential abnormalities to the contralateral asymptomatic side. For these reasons, an AP view of the pelvis with a cross-table lateral view of the symptomatic hip is the standard approach at many institutions, whereas some will include three views: an AP view of the pelvis, a separate AP view of the symptomatic hip, and the cross-table lateral view. There is no specific literature to compare these two approaches.

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Acute Hip Pain Suspected Fracture PCAs

Although they remain the mainstay for initial imaging, pelvis and hip radiographs share the same limitations in sensitivity and specificity for fracture detection, and negative radiographs alone cannot exclude fracture. MRI Pelvis and Affected Hip At least 90% of proximal femoral fractures will be identified on radiographs [21]. Therefore, MRI without intravenous (IV) contrast is reserved for second-line imaging in instances of negative radiographs with continued clinical suspicion for fracture rather than as a first-line modality. Acute Hip Pain-Suspected Fracture The use of contrast-enhanced MRI has been explored as a technique to assess femoral head perfusion in cases of proximal femoral fracture [32,33], but this modality does not play a role in initial imaging assessment. CT Pelvis and Hips Although not as sensitive as MRI, noncontrast CT is also reserved as a problem-solving modality following radiography either to evaluate for radiographically occult fracture or to better depict fracture morphology for treatment planning purposes [34,35]. There is no relevant literature to support the use of contrast-enhanced CT as an initial imaging modality in instances of acute hip pain following low-force trauma. There is no relevant literature to support the use of multiphase CT as an initial imaging modality in instances of acute hip pain following low-force trauma. US Hip Although there has been limited investigation into the use of ultrasound (US) for hip fracture detection, US does not play a role as the initial imaging in this setting [36]. Bone Scan Hips There is no relevant literature to support the use of a nuclear medicine bone scan as an initial imaging modality in instances of acute hip pain following low-force trauma. Variant 2: Acute hip pain. Fall or minor trauma. Negative radiographs. Suspect fracture. Next imaging study.

Acute Hip Pain Suspected Fracture PCAs. Although they remain the mainstay for initial imaging, pelvis and hip radiographs share the same limitations in sensitivity and specificity for fracture detection, and negative radiographs alone cannot exclude fracture. MRI Pelvis and Affected Hip At least 90% of proximal femoral fractures will be identified on radiographs [21]. Therefore, MRI without intravenous (IV) contrast is reserved for second-line imaging in instances of negative radiographs with continued clinical suspicion for fracture rather than as a first-line modality. Acute Hip Pain-Suspected Fracture The use of contrast-enhanced MRI has been explored as a technique to assess femoral head perfusion in cases of proximal femoral fracture [32,33], but this modality does not play a role in initial imaging assessment. CT Pelvis and Hips Although not as sensitive as MRI, noncontrast CT is also reserved as a problem-solving modality following radiography either to evaluate for radiographically occult fracture or to better depict fracture morphology for treatment planning purposes [34,35]. There is no relevant literature to support the use of contrast-enhanced CT as an initial imaging modality in instances of acute hip pain following low-force trauma. There is no relevant literature to support the use of multiphase CT as an initial imaging modality in instances of acute hip pain following low-force trauma. US Hip Although there has been limited investigation into the use of ultrasound (US) for hip fracture detection, US does not play a role as the initial imaging in this setting [36]. Bone Scan Hips There is no relevant literature to support the use of a nuclear medicine bone scan as an initial imaging modality in instances of acute hip pain following low-force trauma. Variant 2: Acute hip pain. Fall or minor trauma. Negative radiographs. Suspect fracture. Next imaging study.

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Acute Hip Pain Suspected Fracture PCAs

MRI Pelvis and Affected Hip There is considerable literature regarding the use of noncontrast MRI for the detection of radiographically occult proximal femoral fractures. An early study by Quinn et al [37] found MRI to be 100% accurate for fracture detection in patients with indeterminate radiographs using clinical outcomes as the gold standard. A subsequent study by Pandey et al [38] found no missed fractures in 10 of 33 patients with negative MRIs, all of whom were followed clinically for at least 6 months. A 2008 study showed 99% sensitivity of MRI, both for proximal femoral fractures and fractures of the pelvis [39]. With multiple studies indicating near 100% sensitivity for proximal femoral fracture, it has been suggested that a negative MRI may allow for confident discharge from the emergency department and reduce the number of cautionary admissions [23,29]. Conversely, rapid diagnosis of surgical fractures reduces delay to treatment with associated improved outcomes [10]. Several additional studies have also shown high diagnostic accuracy for diagnosis of both pelvis fractures and soft-tissue injuries in addition to fractures of the proximal femur [28,30,39]. This versatility is important as many series have shown a high incidence of extrafemoral trauma in patients with acute hip pain and negative radiographs. For example, in the study by Ohishi et al [30], of 113 patients, 38% had fractures of the proximal femur and 33% had fractures of the pelvis. In another retrospective series, Dominguez et al [21] found pelvic fractures to be more common than proximal femur fractures in this patient population, emphasizing the importance of accuracy in the assessment of extrafemoral trauma. Although many of these pelvic fractures and soft-tissue injuries may not be treated surgically, correct diagnosis allows for appropriate conservative treatment, including protected weight-bearing, pain control, deep vein thrombosis prophylaxis, and skilled rehabilitation.

Acute Hip Pain Suspected Fracture PCAs. MRI Pelvis and Affected Hip There is considerable literature regarding the use of noncontrast MRI for the detection of radiographically occult proximal femoral fractures. An early study by Quinn et al [37] found MRI to be 100% accurate for fracture detection in patients with indeterminate radiographs using clinical outcomes as the gold standard. A subsequent study by Pandey et al [38] found no missed fractures in 10 of 33 patients with negative MRIs, all of whom were followed clinically for at least 6 months. A 2008 study showed 99% sensitivity of MRI, both for proximal femoral fractures and fractures of the pelvis [39]. With multiple studies indicating near 100% sensitivity for proximal femoral fracture, it has been suggested that a negative MRI may allow for confident discharge from the emergency department and reduce the number of cautionary admissions [23,29]. Conversely, rapid diagnosis of surgical fractures reduces delay to treatment with associated improved outcomes [10]. Several additional studies have also shown high diagnostic accuracy for diagnosis of both pelvis fractures and soft-tissue injuries in addition to fractures of the proximal femur [28,30,39]. This versatility is important as many series have shown a high incidence of extrafemoral trauma in patients with acute hip pain and negative radiographs. For example, in the study by Ohishi et al [30], of 113 patients, 38% had fractures of the proximal femur and 33% had fractures of the pelvis. In another retrospective series, Dominguez et al [21] found pelvic fractures to be more common than proximal femur fractures in this patient population, emphasizing the importance of accuracy in the assessment of extrafemoral trauma. Although many of these pelvic fractures and soft-tissue injuries may not be treated surgically, correct diagnosis allows for appropriate conservative treatment, including protected weight-bearing, pain control, deep vein thrombosis prophylaxis, and skilled rehabilitation.

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Acute Hip Pain Suspected Fracture PCAs

In addition to its increased sensitivity for fracture detection, MRI has been shown to be useful in characterizing fracture morphology. Seemingly isolated fractures of the greater trochanter diagnosed on radiography frequently have intertrochanteric extension when evaluated with MRI [22]. In a classic study of 30 patients, Schultz et al [40] demonstrated the use of MRI to accurately depict the extent of the fracture line in these radiographically occult intertrochanteric fractures. There is an increasing trend to treat incomplete intertrochanteric fractures conservatively. For example, in a small series of 8 patients, Alam et al [41] found that of the 5 patients treated conservatively, none went on to complete their fracture. Several authors have suggested that with its ability to depict fracture morphology with accuracy, MRI may have a continued role to play in directing treatment [22,40]. Specific scanning protocols have emphasized either speed or comprehensiveness. A 2003 study of 93 cases found 100% sensitivity for the coronal short tau inversion-recovery (STIR) sequence alone [42], and a more recent study found 99% sensitivity of the coronal STIR sequence with increasing confidence and specificity with the addition of a coronal T1 sequence [43]. Given the increasing throughput pressures in the emergency department and the Acute Hip Pain-Suspected Fracture difficulty of older patients in tolerating long scan times, there continues to be interest in developing rapid and accurate MRI protocols. With the diagnostic accuracy of noncontrast MRI approaching 100%, there has been little need to explore the addition of IV gadolinium contrast solely for the purposes of fracture detection. Rather, the interest has been in the use of dynamic MRI to evaluate femoral head perfusion for prognostic purpose to estimate the risks of impaired perfusion, such as osteonecrosis and nonunion.

Acute Hip Pain Suspected Fracture PCAs. In addition to its increased sensitivity for fracture detection, MRI has been shown to be useful in characterizing fracture morphology. Seemingly isolated fractures of the greater trochanter diagnosed on radiography frequently have intertrochanteric extension when evaluated with MRI [22]. In a classic study of 30 patients, Schultz et al [40] demonstrated the use of MRI to accurately depict the extent of the fracture line in these radiographically occult intertrochanteric fractures. There is an increasing trend to treat incomplete intertrochanteric fractures conservatively. For example, in a small series of 8 patients, Alam et al [41] found that of the 5 patients treated conservatively, none went on to complete their fracture. Several authors have suggested that with its ability to depict fracture morphology with accuracy, MRI may have a continued role to play in directing treatment [22,40]. Specific scanning protocols have emphasized either speed or comprehensiveness. A 2003 study of 93 cases found 100% sensitivity for the coronal short tau inversion-recovery (STIR) sequence alone [42], and a more recent study found 99% sensitivity of the coronal STIR sequence with increasing confidence and specificity with the addition of a coronal T1 sequence [43]. Given the increasing throughput pressures in the emergency department and the Acute Hip Pain-Suspected Fracture difficulty of older patients in tolerating long scan times, there continues to be interest in developing rapid and accurate MRI protocols. With the diagnostic accuracy of noncontrast MRI approaching 100%, there has been little need to explore the addition of IV gadolinium contrast solely for the purposes of fracture detection. Rather, the interest has been in the use of dynamic MRI to evaluate femoral head perfusion for prognostic purpose to estimate the risks of impaired perfusion, such as osteonecrosis and nonunion.

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Acute Hip Pain Suspected Fracture PCAs

In one study of 36 patients, impaired femoral head perfusion was more common in patients with displaced fractures, although there was considerable overlap of perfusion pattern and fracture type [44]. The accuracy of predicting successful osseous union was 75% based on fracture morphology and improved incrementally to 89% on the basis of perfusion dynamics. Only 2 of 16 patients with nondisplaced fractures had osteonecrosis. A study from 2009 had similar results with 90% accuracy for prediction of successful fracture union on the basis of femoral head perfusion [45]. However, the study identified only 1 patient with a nondisplaced fracture with impaired femoral head perfusion and did not specify whether this patient went on to osteonecrosis, nor was the accuracy of predicting osteonecrosis on the basis of femoral head perfusion compared to that of the well-established Garden classification system. Given these findings, it is not clear if contrast-enhanced MRI offers significant advantages in the evaluation of the fractured hip compared to existing classification systems. CT Pelvis and Hips CT has advantages over MRI in terms of speed as well as use in patients with significant confusion. There has been considerable investigation into the accuracy of noncontrast CT for detection of radiographically occult proximal femoral fractures, although these studies have been invariably retrospective in nature, have used inconsistent methodology, and at times produced conflicting results. In one study of 199 patients, CT was negative for fracture in 93 patients, and none were found to have undiscovered fractures at 4-month clinical follow-ups [34]. Another similar study with 68 patients found no missed fractures in 27 patients with negative CT scans, although it was not clear if clinical follow-up was as comprehensive [46]. However, a number of other studies have demonstrated potential limitations in the sensitivity of CT.

Acute Hip Pain Suspected Fracture PCAs. In one study of 36 patients, impaired femoral head perfusion was more common in patients with displaced fractures, although there was considerable overlap of perfusion pattern and fracture type [44]. The accuracy of predicting successful osseous union was 75% based on fracture morphology and improved incrementally to 89% on the basis of perfusion dynamics. Only 2 of 16 patients with nondisplaced fractures had osteonecrosis. A study from 2009 had similar results with 90% accuracy for prediction of successful fracture union on the basis of femoral head perfusion [45]. However, the study identified only 1 patient with a nondisplaced fracture with impaired femoral head perfusion and did not specify whether this patient went on to osteonecrosis, nor was the accuracy of predicting osteonecrosis on the basis of femoral head perfusion compared to that of the well-established Garden classification system. Given these findings, it is not clear if contrast-enhanced MRI offers significant advantages in the evaluation of the fractured hip compared to existing classification systems. CT Pelvis and Hips CT has advantages over MRI in terms of speed as well as use in patients with significant confusion. There has been considerable investigation into the accuracy of noncontrast CT for detection of radiographically occult proximal femoral fractures, although these studies have been invariably retrospective in nature, have used inconsistent methodology, and at times produced conflicting results. In one study of 199 patients, CT was negative for fracture in 93 patients, and none were found to have undiscovered fractures at 4-month clinical follow-ups [34]. Another similar study with 68 patients found no missed fractures in 27 patients with negative CT scans, although it was not clear if clinical follow-up was as comprehensive [46]. However, a number of other studies have demonstrated potential limitations in the sensitivity of CT.

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Acute Hip Pain Suspected Fracture PCAs

For example, Haubro et al [26] found a sensitivity for CT of 87% compared with 100% for MRI, with CT missing 6 of 15 fractures. Another larger study of 129 cases compared MRI and CT for the diagnosis of both proximal femoral and pelvic fractures and found a sensitivity of 99% for MRI and 69% for CT using clinical outcomes and follow-up imaging as the gold standard [39]. This same study by Cabarrus et al [39] also found MRI to be substantially better at detecting soft-tissue abnormalities with 99% sensitivity for MRI and 13% sensitivity edema, and the differences in sensitivity for more significant injuries, such as hematoma or tendon avulsion, may be somewhat less. Several other similar studies comparing CT and MRI have also shown decreased sensitivity of CT with potential for missed fractures as well as changes in diagnosis and management when MRI is obtained after CT [24,47,48]. There is no relevant data to support the use of contrast-enhanced CT solely for the purpose of fracture detection following negative radiographs. However, if contrast-enhanced CT examination of the abdomen and pelvis is performed because of suspicion of concurrent intra-abdominal trauma, bone algorithm reconstruction of the pelvis and hips may be performed rather than performing a separate examination. There is no relevant data to support the use of multiphase CT for the detection of fractures of the pelvis and proximal femur. Dual-energy CT is a more recent technology that has the ability to produce virtual noncalcium images for the detection of bone marrow edema. Although the technology holds promise, diagnostic accuracy does not yet approach that of MRI, with an initial study by Reddy et al [49] demonstrating a sensitivity of 90% and specificity of 40% for nondisplaced femoral neck fractures. However, this may be a modality of emerging importance as technology improves.

Acute Hip Pain Suspected Fracture PCAs. For example, Haubro et al [26] found a sensitivity for CT of 87% compared with 100% for MRI, with CT missing 6 of 15 fractures. Another larger study of 129 cases compared MRI and CT for the diagnosis of both proximal femoral and pelvic fractures and found a sensitivity of 99% for MRI and 69% for CT using clinical outcomes and follow-up imaging as the gold standard [39]. This same study by Cabarrus et al [39] also found MRI to be substantially better at detecting soft-tissue abnormalities with 99% sensitivity for MRI and 13% sensitivity edema, and the differences in sensitivity for more significant injuries, such as hematoma or tendon avulsion, may be somewhat less. Several other similar studies comparing CT and MRI have also shown decreased sensitivity of CT with potential for missed fractures as well as changes in diagnosis and management when MRI is obtained after CT [24,47,48]. There is no relevant data to support the use of contrast-enhanced CT solely for the purpose of fracture detection following negative radiographs. However, if contrast-enhanced CT examination of the abdomen and pelvis is performed because of suspicion of concurrent intra-abdominal trauma, bone algorithm reconstruction of the pelvis and hips may be performed rather than performing a separate examination. There is no relevant data to support the use of multiphase CT for the detection of fractures of the pelvis and proximal femur. Dual-energy CT is a more recent technology that has the ability to produce virtual noncalcium images for the detection of bone marrow edema. Although the technology holds promise, diagnostic accuracy does not yet approach that of MRI, with an initial study by Reddy et al [49] demonstrating a sensitivity of 90% and specificity of 40% for nondisplaced femoral neck fractures. However, this may be a modality of emerging importance as technology improves.

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Acute Hip Pain Suspected Fracture PCAs

US Hip The use of US for evaluation of the acutely painful hip has been evaluated in a single study of 10 patients with hip fractures [36]. Although US was able to identify trauma-related changes, such as joint effusion, with 100% sensitivity, specificity for fracture reached only 65%. The authors acknowledged that performance might further decrease for examinations performed by sonographers and radiologists not experienced with musculoskeletal US. For this document, it is assumed the procedure is performed and interpreted by an expert. Given the inability of US to comprehensively evaluate the bones and soft tissues of the pelvis, there is not enough evidence to support the role of US in the workup of radiographically occult hip fracture. Acute Hip Pain-Suspected Fracture Bone Scan Hips Prior to the advent of MRI, a bone scan was the preferred test for radiographically occult proximal femoral fractures. However, as early as 1993, Rizzo et al [50] demonstrated MRI to be at least as accurate as bone scans and with substantially decreased time to diagnosis. A later study by Rubin et al [51] comparing bone scans and MRI demonstrated improved sensitivity and specificity of MRI relative to bone scans. Moreover, the bone scan group averaged an additional day to surgery. Bone scintigraphy is a time-consuming process. Bone scans may be falsely negative for up to 72 hours from the time of injury, and false-positive scans are likewise common, related to osteoarthritis, soft-tissue injury, or any other process that may increase bone turnover [50]. It has been postulated that performing single-photon emission computed tomography may combine the sensitivity of bone scintigraphy with the spatial accuracy of CT, but there are no data to support this view. In current practice, the role of bone scans as a secondary line of imaging in patients with contraindications to MRI has largely been usurped by CT.

Acute Hip Pain Suspected Fracture PCAs. US Hip The use of US for evaluation of the acutely painful hip has been evaluated in a single study of 10 patients with hip fractures [36]. Although US was able to identify trauma-related changes, such as joint effusion, with 100% sensitivity, specificity for fracture reached only 65%. The authors acknowledged that performance might further decrease for examinations performed by sonographers and radiologists not experienced with musculoskeletal US. For this document, it is assumed the procedure is performed and interpreted by an expert. Given the inability of US to comprehensively evaluate the bones and soft tissues of the pelvis, there is not enough evidence to support the role of US in the workup of radiographically occult hip fracture. Acute Hip Pain-Suspected Fracture Bone Scan Hips Prior to the advent of MRI, a bone scan was the preferred test for radiographically occult proximal femoral fractures. However, as early as 1993, Rizzo et al [50] demonstrated MRI to be at least as accurate as bone scans and with substantially decreased time to diagnosis. A later study by Rubin et al [51] comparing bone scans and MRI demonstrated improved sensitivity and specificity of MRI relative to bone scans. Moreover, the bone scan group averaged an additional day to surgery. Bone scintigraphy is a time-consuming process. Bone scans may be falsely negative for up to 72 hours from the time of injury, and false-positive scans are likewise common, related to osteoarthritis, soft-tissue injury, or any other process that may increase bone turnover [50]. It has been postulated that performing single-photon emission computed tomography may combine the sensitivity of bone scintigraphy with the spatial accuracy of CT, but there are no data to support this view. In current practice, the role of bone scans as a secondary line of imaging in patients with contraindications to MRI has largely been usurped by CT.

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acrac_69435_0

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Introduction/Background Stress fractures occur in 2 varieties: 1) fatigue fractures resulting from repetitive submaximal stress on normal bone, resulting in a region of accelerated bone remodeling [1] and 2) insufficiency fractures due to normal activity on bones that are deficient in microstructure and/or mineralization [2]. At the microscopic level, repetitive overloading leads to increased osteoclastic activity that exceeds the rate of osteoblastic new bone formation. This results in bone weakening and microtrabecular disruption (stress injury) and eventually may lead to a cortical break (stress fracture). Stress fractures are encountered frequently and account for up to 20% of all injuries seen in sports medicine clinics [1,3-6]. The fatigue variation of stress fractures are particularly common in athletes participating in activities that require running and jumping, as well as in ballet dancers and military recruits [7-9]. Certain medical interventions such as radiation therapy and long-term osteoporosis treatment with bisphosphonates predispose patients to the insufficiency variation of stress fractures [10-12]. OR Discussion of Procedures by Variant Variant 1: Adult. Suspect stress fracture, excluding vertebrae. Initial imaging. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, ribs, sacrum, shoulder, or wrist. In the setting of new or repetitive athletic activity, fatigue fractures can develop in patients with normal bone. Furthermore, certain athletic activities often result in specific sites of fatigue fracture, such as olecranon process fractures in javelin throwers and baseball pitchers, proximal femur and tibial stress fractures in runners, and tarsal navicular stress fractures in basketball players [13-15]. Insufficiency fractures occur in patients with abnormal bone, be it from osteoporosis or irradiated bone, as typical examples.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Introduction/Background Stress fractures occur in 2 varieties: 1) fatigue fractures resulting from repetitive submaximal stress on normal bone, resulting in a region of accelerated bone remodeling [1] and 2) insufficiency fractures due to normal activity on bones that are deficient in microstructure and/or mineralization [2]. At the microscopic level, repetitive overloading leads to increased osteoclastic activity that exceeds the rate of osteoblastic new bone formation. This results in bone weakening and microtrabecular disruption (stress injury) and eventually may lead to a cortical break (stress fracture). Stress fractures are encountered frequently and account for up to 20% of all injuries seen in sports medicine clinics [1,3-6]. The fatigue variation of stress fractures are particularly common in athletes participating in activities that require running and jumping, as well as in ballet dancers and military recruits [7-9]. Certain medical interventions such as radiation therapy and long-term osteoporosis treatment with bisphosphonates predispose patients to the insufficiency variation of stress fractures [10-12]. OR Discussion of Procedures by Variant Variant 1: Adult. Suspect stress fracture, excluding vertebrae. Initial imaging. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, ribs, sacrum, shoulder, or wrist. In the setting of new or repetitive athletic activity, fatigue fractures can develop in patients with normal bone. Furthermore, certain athletic activities often result in specific sites of fatigue fracture, such as olecranon process fractures in javelin throwers and baseball pitchers, proximal femur and tibial stress fractures in runners, and tarsal navicular stress fractures in basketball players [13-15]. Insufficiency fractures occur in patients with abnormal bone, be it from osteoporosis or irradiated bone, as typical examples.

69435

acrac_69435_1

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Insufficiency fractures also occur at fairly predictable aThomas Jefferson University Hospital, Philadelphia, Pennsylvania. bResearch Author, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania. cPanel Chair, Mayo Clinic Arizona, Phoenix, Arizona. dUniversity of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. eMichigan State University, East Lansing, Michigan; American Academy of Orthopaedic Surgeons. fPenn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania. gMayo Clinic, Rochester, Minnesota. hHospital for Special Surgery, New York, New York. iBrigham & Women's Hospital, Boston, Massachusetts; Committee on Emergency Radiology-GSER. jMayo Clinic Arizona, Glendale, Arizona, Primary care physician. kUniversity of Virginia Health System, Charlottesville, Virginia. lMedical University of South Carolina, Charleston, South Carolina; North American Spine Society. mDuke University Medical Center, Durham, North Carolina. nUniversity of Missouri Health Care, Columbia, Missouri. oPenn State Milton S. Hershey Medical Center, Hershey, Pennsylvania and Uniformed Services University of the Health Sciences, Bethesda, Maryland. pSpecialty Chair, VA San Diego Healthcare System, San Diego, California. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Stress (Fatigue-Insufficiency) Fracture sites, including the sacrum, supra-acetabular ilium, superior and inferior pubic rami, and pubic bone. These patients often present with intractable low back and/or pelvic pain [16].

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Insufficiency fractures also occur at fairly predictable aThomas Jefferson University Hospital, Philadelphia, Pennsylvania. bResearch Author, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania. cPanel Chair, Mayo Clinic Arizona, Phoenix, Arizona. dUniversity of Wisconsin School of Medicine and Public Health, Madison, Wisconsin. eMichigan State University, East Lansing, Michigan; American Academy of Orthopaedic Surgeons. fPenn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania. gMayo Clinic, Rochester, Minnesota. hHospital for Special Surgery, New York, New York. iBrigham & Women's Hospital, Boston, Massachusetts; Committee on Emergency Radiology-GSER. jMayo Clinic Arizona, Glendale, Arizona, Primary care physician. kUniversity of Virginia Health System, Charlottesville, Virginia. lMedical University of South Carolina, Charleston, South Carolina; North American Spine Society. mDuke University Medical Center, Durham, North Carolina. nUniversity of Missouri Health Care, Columbia, Missouri. oPenn State Milton S. Hershey Medical Center, Hershey, Pennsylvania and Uniformed Services University of the Health Sciences, Bethesda, Maryland. pSpecialty Chair, VA San Diego Healthcare System, San Diego, California. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Stress (Fatigue-Insufficiency) Fracture sites, including the sacrum, supra-acetabular ilium, superior and inferior pubic rami, and pubic bone. These patients often present with intractable low back and/or pelvic pain [16].

69435

acrac_69435_2

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Bone Scan Whole Body with SPECT or SPECT/CT Area of Interest The bone scan was regarded for many years as the reference standard for detecting stress-induced injuries and was valued for its sensitivity. Dobrindt et al [17] reported the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of bone scintigraphy for detection of stress injuries as 92.9%, 73.8%, 83.3%, 78.0%, and 91.2%, respectively. Planar scintigraphy combined with single-photon emission CT (SPECT) is more accurate in diagnosing stress injuries than planar scintigraphy alone [18]. The objection to the studies quoting high accuracy for bone scintigraphy is that, in all of them, positive bone scintigraphy is taken as the reference standard for detecting stress fractures and therefore sensitivity is 100%. However, depending on the staging criteria for bone scintigraphy pattern, the abnormalities may in fact be stress reactions rather than actual stress fractures [19-21]. Nonetheless, bone scintigraphy shows stress fractures days to weeks earlier than radiographs in many instances and differentiates between osseous and soft tissue injury as well. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with intravenous (IV) contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT is not supported for the initial imaging of suspected stress fractures but may offer an adjunct role when other imaging modalities are equivocal [22], particularly in the pelvis or sacrum.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Bone Scan Whole Body with SPECT or SPECT/CT Area of Interest The bone scan was regarded for many years as the reference standard for detecting stress-induced injuries and was valued for its sensitivity. Dobrindt et al [17] reported the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of bone scintigraphy for detection of stress injuries as 92.9%, 73.8%, 83.3%, 78.0%, and 91.2%, respectively. Planar scintigraphy combined with single-photon emission CT (SPECT) is more accurate in diagnosing stress injuries than planar scintigraphy alone [18]. The objection to the studies quoting high accuracy for bone scintigraphy is that, in all of them, positive bone scintigraphy is taken as the reference standard for detecting stress fractures and therefore sensitivity is 100%. However, depending on the staging criteria for bone scintigraphy pattern, the abnormalities may in fact be stress reactions rather than actual stress fractures [19-21]. Nonetheless, bone scintigraphy shows stress fractures days to weeks earlier than radiographs in many instances and differentiates between osseous and soft tissue injury as well. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with intravenous (IV) contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT is not supported for the initial imaging of suspected stress fractures but may offer an adjunct role when other imaging modalities are equivocal [22], particularly in the pelvis or sacrum.

69435

acrac_69435_3

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Although superior to radiography, it is less sensitive than nuclear scintigraphy or MRI [23]. The benefit of CT seems to lie in its specificity, ranging from 88% to 98% in a recent meta-analysis regarding accuracy of imaging modalities for lower extremity stress fractures, and thus may confirm a finding suspected to represent stress fracture on MRI [24]. CT may also be useful in cases where MRI results are equivocal. MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. MRI Area of Interest Without IV Contrast MRI demonstrates stress abnormalities as early as bone scintigraphy and with as much sensitivity [25-28]. In the absence of an actual stress fracture, stress reaction, or muscle/tendon injuries can be identified using fluid-sensitive sequences. Thus, MRI may be considerably more specific than scintigraphy [22,23]. The recent literature supports MRI as the procedure of choice for early diagnosis of both fatigue and insufficiency types of stress fractures, outperforming all other modalities [15,22,23,29-39]. Fluid-sensitive sequences are the favored initial sequence for MRI screening [40]. Short tau inversion recovery (STIR) and T1-weighted images demonstrate a fracture line surrounded by edema. MRI of an osseous stress injury contains prognostic as well as diagnostic information [41,42]. Radiography Area of Interest Radiographs are insensitive for stress fracture in the early stages of injury and in elderly patients with underlying osteoporosis. However, if symptoms have been present for at least 10 to 14 days, radiographs can achieve sensitivity of 30% to 70%, making them an effective screening tool [43]. If the findings on radiographs are conclusive for stress fracture, often no further imaging needs to be performed.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Although superior to radiography, it is less sensitive than nuclear scintigraphy or MRI [23]. The benefit of CT seems to lie in its specificity, ranging from 88% to 98% in a recent meta-analysis regarding accuracy of imaging modalities for lower extremity stress fractures, and thus may confirm a finding suspected to represent stress fracture on MRI [24]. CT may also be useful in cases where MRI results are equivocal. MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. MRI Area of Interest Without IV Contrast MRI demonstrates stress abnormalities as early as bone scintigraphy and with as much sensitivity [25-28]. In the absence of an actual stress fracture, stress reaction, or muscle/tendon injuries can be identified using fluid-sensitive sequences. Thus, MRI may be considerably more specific than scintigraphy [22,23]. The recent literature supports MRI as the procedure of choice for early diagnosis of both fatigue and insufficiency types of stress fractures, outperforming all other modalities [15,22,23,29-39]. Fluid-sensitive sequences are the favored initial sequence for MRI screening [40]. Short tau inversion recovery (STIR) and T1-weighted images demonstrate a fracture line surrounded by edema. MRI of an osseous stress injury contains prognostic as well as diagnostic information [41,42]. Radiography Area of Interest Radiographs are insensitive for stress fracture in the early stages of injury and in elderly patients with underlying osteoporosis. However, if symptoms have been present for at least 10 to 14 days, radiographs can achieve sensitivity of 30% to 70%, making them an effective screening tool [43]. If the findings on radiographs are conclusive for stress fracture, often no further imaging needs to be performed.

69435

acrac_69435_4

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Detection of osseous change is limited in areas covered by prominent overlapping soft tissue or bowel gas [31]. If the osseous reaction involves cortical bone, then endosteal/periosteal callus may be visible with or without a fracture line through the cortex. If the trabecular bone is involved, then stress fractures are often more subtle, progressing from patchy areas of increased density into linear areas of sclerosis, oriented perpendicular to the trabeculae. US Area of Interest There is increasing evidence of the usefulness of ultrasound (US) in the early diagnosis of stress fractures of the extremities [44,45]. Although later US findings of stress fractures, including subcutaneous edema, periosteal thickening, cortical bone irregularity, local hyperemia [44-46], and periosteal callus are often nonspecific, these Stress (Fatigue-Insufficiency) Fracture findings provide useful information in the setting of suspected stress fracture. Because US cannot evaluate the subcortical bone, trabecular stress fractures may be missed. Variant 2: Adult. Suspect stress fracture, excluding vertebrae. Radiographs negative or indeterminate. Next imaging study. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, ribs, sacrum, shoulder, or wrist. Bone Scan Whole Body with SPECT or SPECT/CT Area of Interest Bone scintigraphy shows stress fractures days to weeks earlier than radiographs in many instances and differentiates between osseous and soft tissue injury as well. Although bone scan was regarded as the reference standard examination for many years, MRI demonstrates stress abnormalities as early as bone scintigraphy and with as much sensitivity [25-28].

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Detection of osseous change is limited in areas covered by prominent overlapping soft tissue or bowel gas [31]. If the osseous reaction involves cortical bone, then endosteal/periosteal callus may be visible with or without a fracture line through the cortex. If the trabecular bone is involved, then stress fractures are often more subtle, progressing from patchy areas of increased density into linear areas of sclerosis, oriented perpendicular to the trabeculae. US Area of Interest There is increasing evidence of the usefulness of ultrasound (US) in the early diagnosis of stress fractures of the extremities [44,45]. Although later US findings of stress fractures, including subcutaneous edema, periosteal thickening, cortical bone irregularity, local hyperemia [44-46], and periosteal callus are often nonspecific, these Stress (Fatigue-Insufficiency) Fracture findings provide useful information in the setting of suspected stress fracture. Because US cannot evaluate the subcortical bone, trabecular stress fractures may be missed. Variant 2: Adult. Suspect stress fracture, excluding vertebrae. Radiographs negative or indeterminate. Next imaging study. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, ribs, sacrum, shoulder, or wrist. Bone Scan Whole Body with SPECT or SPECT/CT Area of Interest Bone scintigraphy shows stress fractures days to weeks earlier than radiographs in many instances and differentiates between osseous and soft tissue injury as well. Although bone scan was regarded as the reference standard examination for many years, MRI demonstrates stress abnormalities as early as bone scintigraphy and with as much sensitivity [25-28].

69435

acrac_69435_5

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Because standard planar whole body bone scintigraphy is often nonspecific and supplemental imaging is frequently required, there is consensus in the literature that MRI should supersede bone scintigraphy as the imaging examination of choice for suspected stress fracture when radiographs are negative [31]. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT is not supported as the next imaging study for suspected stress fractures following radiographs but may offer an adjunctive role when other imaging modalities are equivocal [22]. Although superior to radiography, it is less sensitive than nuclear scintigraphy and MRI [23]. CT is useful in cases where MRI results are equivocal. MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. MRI Area of Interest Without IV Contrast MRI outperforms radiography, bone scintigraphy, and CT with recent literature supporting MRI as the procedure of choice for making an early diagnosis of both fatigue and insufficiency fractures [15,22,23,29-39]. MRI of an osseous stress injury contains prognostic as well as diagnostic information [41,42].

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Because standard planar whole body bone scintigraphy is often nonspecific and supplemental imaging is frequently required, there is consensus in the literature that MRI should supersede bone scintigraphy as the imaging examination of choice for suspected stress fracture when radiographs are negative [31]. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT is not supported as the next imaging study for suspected stress fractures following radiographs but may offer an adjunctive role when other imaging modalities are equivocal [22]. Although superior to radiography, it is less sensitive than nuclear scintigraphy and MRI [23]. CT is useful in cases where MRI results are equivocal. MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. MRI Area of Interest Without IV Contrast MRI outperforms radiography, bone scintigraphy, and CT with recent literature supporting MRI as the procedure of choice for making an early diagnosis of both fatigue and insufficiency fractures [15,22,23,29-39]. MRI of an osseous stress injury contains prognostic as well as diagnostic information [41,42].

69435

acrac_69435_6

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Radiography Area of Interest Repeat In 10-14 Days Short-term (10-14 days) follow-up radiographs are more sensitive than initial radiographs secondary to overt bone reaction in the location of the stress fracture. Follow-up radiographic sensitivity is reported to be 30% to 70% [43]. Detection of osseous change is more limited in areas covered by prominent overlapping soft tissue [31]. If the osseous reaction involves cortical bone, then endosteal/periosteal callus may be visible with or without a fracture line through the cortex. If the trabecular bone is involved, then stress fractures are often more subtle, progressing from patchy areas of increased density into linear areas of sclerosis, oriented perpendicular to the trabeculae. US Area of Interest There is increasing evidence of the usefulness of US in the early diagnosis of stress fractures of the extremities [44,45]. Although later US findings of stress fractures, including subcutaneous edema, periosteal thickening, cortical bone irregularity, local hyperemia [44-46], and periosteal callus are often nonspecific, these findings provide useful information in the setting of suspected stress fracture. Because US cannot evaluate the subcortical bone, trabecular stress fractures may be missed. Variant 3: Adult. Suspect pelvis or hip or sacrum stress fracture. Pregnant patient. Radiographs negative or indeterminate. Next imaging study. Area of Interest: pelvis, hip, or sacrum. Pelvic and hip insufficiency fractures have varied presentations and often insidious onset. Patients frequently present with intractable lower back or pelvic pain, with loss of mobility, independence, and symptom exacerbation Stress (Fatigue-Insufficiency) Fracture with weight bearing [47]. Insufficiency fractures occur in patients with abnormal bone, be it from osteoporosis, irradiated bone, or resumption of activity.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Radiography Area of Interest Repeat In 10-14 Days Short-term (10-14 days) follow-up radiographs are more sensitive than initial radiographs secondary to overt bone reaction in the location of the stress fracture. Follow-up radiographic sensitivity is reported to be 30% to 70% [43]. Detection of osseous change is more limited in areas covered by prominent overlapping soft tissue [31]. If the osseous reaction involves cortical bone, then endosteal/periosteal callus may be visible with or without a fracture line through the cortex. If the trabecular bone is involved, then stress fractures are often more subtle, progressing from patchy areas of increased density into linear areas of sclerosis, oriented perpendicular to the trabeculae. US Area of Interest There is increasing evidence of the usefulness of US in the early diagnosis of stress fractures of the extremities [44,45]. Although later US findings of stress fractures, including subcutaneous edema, periosteal thickening, cortical bone irregularity, local hyperemia [44-46], and periosteal callus are often nonspecific, these findings provide useful information in the setting of suspected stress fracture. Because US cannot evaluate the subcortical bone, trabecular stress fractures may be missed. Variant 3: Adult. Suspect pelvis or hip or sacrum stress fracture. Pregnant patient. Radiographs negative or indeterminate. Next imaging study. Area of Interest: pelvis, hip, or sacrum. Pelvic and hip insufficiency fractures have varied presentations and often insidious onset. Patients frequently present with intractable lower back or pelvic pain, with loss of mobility, independence, and symptom exacerbation Stress (Fatigue-Insufficiency) Fracture with weight bearing [47]. Insufficiency fractures occur in patients with abnormal bone, be it from osteoporosis, irradiated bone, or resumption of activity.

69435

acrac_69435_7

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Imaging findings of pregnancy-related sacral fractures are similar to sacral insufficiency fractures related to involutional osteoporosis, with the exception that patients will be in their reproductive years and in the last trimester of pregnancy or recently postpartum [56,57]. Bone Scan Whole Body with SPECT or SPECT/CT Area of Interest Bone scintigraphy and CT are both associated with radiation exposure to the fetus in a pregnant patient. For reference, the approximate mean fetal absorbed dose from a pelvis radiograph is 1.1 mGy, from a pelvis CT is 25 mGy, and from a bone scintigraphy is 4.6 mGy (early in pregnancy) and 1.8 mGy (at 9 months estimated gestational age) [62]. Because bone scintigraphy is often nonspecific and supplemental imaging is frequently required, there is consensus in the literature that cross-sectional imaging should supersede bone scintigraphy as the imaging of choice for suspected insufficiency fracture when the radiograph is negative, regardless of the risks of radiation exposure [31]. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT and bone scintigraphy are both associated with radiation exposure to the fetus in a pregnant patient [62]. Therefore, MRI is preferred. MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Imaging findings of pregnancy-related sacral fractures are similar to sacral insufficiency fractures related to involutional osteoporosis, with the exception that patients will be in their reproductive years and in the last trimester of pregnancy or recently postpartum [56,57]. Bone Scan Whole Body with SPECT or SPECT/CT Area of Interest Bone scintigraphy and CT are both associated with radiation exposure to the fetus in a pregnant patient. For reference, the approximate mean fetal absorbed dose from a pelvis radiograph is 1.1 mGy, from a pelvis CT is 25 mGy, and from a bone scintigraphy is 4.6 mGy (early in pregnancy) and 1.8 mGy (at 9 months estimated gestational age) [62]. Because bone scintigraphy is often nonspecific and supplemental imaging is frequently required, there is consensus in the literature that cross-sectional imaging should supersede bone scintigraphy as the imaging of choice for suspected insufficiency fracture when the radiograph is negative, regardless of the risks of radiation exposure [31]. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT and bone scintigraphy are both associated with radiation exposure to the fetus in a pregnant patient [62]. Therefore, MRI is preferred. MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury.

69435

acrac_69435_8

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

MRI Area of Interest Without IV Contrast Given the importance of recognizing these high-risk fractures in the femoral head and neck, MRI is the preferred second-line study after initial negative radiographs to prevent delayed diagnosis. MRI does not use ionizing radiation, has excellent sensitivity, and allows for definitive diagnosis. MRI typically demonstrates linear T1 and T2 hypointense signal, representing fracture lines, and T1 hypointense and T2 hyperintense signal in the surrounding bone marrow, representing associated edema. MRI demonstrates stress abnormalities as early as bone scintigraphy and with as much sensitivity [25-28]. Stress (Fatigue-Insufficiency) Fracture In addition to confirming a suspected stress fracture, MRI may also demonstrate other reasons for occult pelvic pain, such as soft tissue abnormalities or the subchondral hip or supra-acetabular stress fractures described in some patients with osteoporosis [57]. Radiography Area of Interest Repeat In 10-14 Days A follow-up radiographic examination has increased sensitivity compared to initial radiographs [43] but is less sensitive than MRI. US Area of Interest There is increasing evidence of the usefulness of US in the early diagnosis of stress fractures of the distal extremities [44,45] and may allow visualization of posterior sacral fractures without the risk of ionizing radiation. However, definitive diagnosis of suspected hip or pelvic fractures should not be delayed by choosing US as the second-line study following negative or indeterminate radiographs, considering that additional imaging may be required following a negative or US indeterminate examination. Patients at high-risk for fracture completion include patients with osteoporosis, those on bisphosphonate therapy, and athletes.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. MRI Area of Interest Without IV Contrast Given the importance of recognizing these high-risk fractures in the femoral head and neck, MRI is the preferred second-line study after initial negative radiographs to prevent delayed diagnosis. MRI does not use ionizing radiation, has excellent sensitivity, and allows for definitive diagnosis. MRI typically demonstrates linear T1 and T2 hypointense signal, representing fracture lines, and T1 hypointense and T2 hyperintense signal in the surrounding bone marrow, representing associated edema. MRI demonstrates stress abnormalities as early as bone scintigraphy and with as much sensitivity [25-28]. Stress (Fatigue-Insufficiency) Fracture In addition to confirming a suspected stress fracture, MRI may also demonstrate other reasons for occult pelvic pain, such as soft tissue abnormalities or the subchondral hip or supra-acetabular stress fractures described in some patients with osteoporosis [57]. Radiography Area of Interest Repeat In 10-14 Days A follow-up radiographic examination has increased sensitivity compared to initial radiographs [43] but is less sensitive than MRI. US Area of Interest There is increasing evidence of the usefulness of US in the early diagnosis of stress fractures of the distal extremities [44,45] and may allow visualization of posterior sacral fractures without the risk of ionizing radiation. However, definitive diagnosis of suspected hip or pelvic fractures should not be delayed by choosing US as the second-line study following negative or indeterminate radiographs, considering that additional imaging may be required following a negative or US indeterminate examination. Patients at high-risk for fracture completion include patients with osteoporosis, those on bisphosphonate therapy, and athletes.

69435

acrac_69435_9

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Stress fractures in this population that are not identified and managed in a timely fashion can progress to more serious fractures and complications (eg, risk of fatty emboli in completed femoral shaft fractures). Preventive strategies, including identifying and modifying risk factors, may help deter progression to complete fracture [42,63,64]. Certain stress fractures are considered high risk based on a tendency for nonunion or delayed union. High-risk stress fractures include the anterior tibial diaphysis, lateral femoral neck and femoral head, patella, medial malleolus, navicular, fifth metatarsal base, proximal second metatarsal, tibial hallux sesamoid, and talus [65]. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. Stress (Fatigue-Insufficiency) Fracture CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT is not supported as the next imaging study for suspected stress fractures following radiographs but may offer an adjunctive role when other imaging modalities are equivocal [22]. Although superior to radiography, it is less sensitive than nuclear scintigraphy or MRI [23]. The benefit of CT seems to lie in its specificity, ranging from 88% to 98% in a recent meta-analysis regarding accuracy of imaging modalities for lower extremity stress fractures and thus may confirm a finding suspected to represent stress fracture on MRI [24].

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Stress fractures in this population that are not identified and managed in a timely fashion can progress to more serious fractures and complications (eg, risk of fatty emboli in completed femoral shaft fractures). Preventive strategies, including identifying and modifying risk factors, may help deter progression to complete fracture [42,63,64]. Certain stress fractures are considered high risk based on a tendency for nonunion or delayed union. High-risk stress fractures include the anterior tibial diaphysis, lateral femoral neck and femoral head, patella, medial malleolus, navicular, fifth metatarsal base, proximal second metatarsal, tibial hallux sesamoid, and talus [65]. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. Stress (Fatigue-Insufficiency) Fracture CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT is not supported as the next imaging study for suspected stress fractures following radiographs but may offer an adjunctive role when other imaging modalities are equivocal [22]. Although superior to radiography, it is less sensitive than nuclear scintigraphy or MRI [23]. The benefit of CT seems to lie in its specificity, ranging from 88% to 98% in a recent meta-analysis regarding accuracy of imaging modalities for lower extremity stress fractures and thus may confirm a finding suspected to represent stress fracture on MRI [24].

69435

acrac_69435_10

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. MRI Area of Interest Without IV Contrast MRI is beneficial after initial negative radiographs to prevent delayed diagnosis. MRI has excellent sensitivity, and it allows for definitive diagnosis. MRI typically demonstrates linear T1 and T2 hypointense signal, representing fracture lines, and T1 hypointense and T2 hyperintense signal in the surrounding bone marrow, representing associated edema. MRI demonstrates stress abnormalities as early as bone scintigraphy but with more specificity [25-28]. US Area of Interest There is increasing evidence of the usefulness of US in the early diagnosis of stress fractures of the distal extremities [44,45] and may allow for visualization of posterior sacral fractures. However, definitive diagnosis of suspected hip or pelvic fractures should not be delayed by choosing US as the second-line study following negative or indeterminate radiographs, considering that additional imaging may be required following a negative or US indeterminate examination. Variant 5: Adult. Suspect subchondral stress fracture at an extremity joint. Radiographs negative or indeterminate. Next imaging study. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, shoulder, or wrist. Bone Scan Whole Body with SPECT or SPECT/CT Area of Interest Normal bone scintigraphy generally excludes a diagnosis of stress fracture, and the patient can return to normal activity. Tc-99m-methyl diphosphonate is a marker of bone perfusion and bone turnover [68]. Relative uptake is dependent on both the perfusion of a region of bone as well as the area of the mineralization front of bone (eg, osteoid).

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. MRI Area of Interest Without IV Contrast MRI is beneficial after initial negative radiographs to prevent delayed diagnosis. MRI has excellent sensitivity, and it allows for definitive diagnosis. MRI typically demonstrates linear T1 and T2 hypointense signal, representing fracture lines, and T1 hypointense and T2 hyperintense signal in the surrounding bone marrow, representing associated edema. MRI demonstrates stress abnormalities as early as bone scintigraphy but with more specificity [25-28]. US Area of Interest There is increasing evidence of the usefulness of US in the early diagnosis of stress fractures of the distal extremities [44,45] and may allow for visualization of posterior sacral fractures. However, definitive diagnosis of suspected hip or pelvic fractures should not be delayed by choosing US as the second-line study following negative or indeterminate radiographs, considering that additional imaging may be required following a negative or US indeterminate examination. Variant 5: Adult. Suspect subchondral stress fracture at an extremity joint. Radiographs negative or indeterminate. Next imaging study. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, shoulder, or wrist. Bone Scan Whole Body with SPECT or SPECT/CT Area of Interest Normal bone scintigraphy generally excludes a diagnosis of stress fracture, and the patient can return to normal activity. Tc-99m-methyl diphosphonate is a marker of bone perfusion and bone turnover [68]. Relative uptake is dependent on both the perfusion of a region of bone as well as the area of the mineralization front of bone (eg, osteoid).

69435

acrac_69435_11

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Thus, there will be focal uptake in any location of new bone formation. Although bone scintigraphy is very sensitive for stress reactions, including subchondral stress fractures, in most cases it lacks specificity, with synovitis, arthritis, degenerative joint disease, stress reactions, and tumor appearing similar. Supplemental imaging with MRI may be necessary for conclusive diagnosis or to avoid false positives [66]. Because planar bone scintigraphy is often nonspecific and supplemental imaging is frequently required, there is consensus in the literature that cross-sectional imaging should supersede planar bone scintigraphy as the imaging of choice for suspected stress fractures when the radiograph is negative [31]. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. Stress (Fatigue-Insufficiency) Fracture CT Area of Interest Without IV Contrast CT is not supported as the next imaging study for suspected subchondral stress fractures following radiographs but may offer an adjunctive role when other imaging modalities are equivocal [22]. Although superior to radiography, it is less sensitive than nuclear scintigraphy or MRI [23]. The value of CT in the setting of suspected subchondral stress fracture primarily lies in detection of articular surface collapse and sclerosis that could indicate secondary necrosis. CT is useful in cases in which MRI results are equivocal.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Thus, there will be focal uptake in any location of new bone formation. Although bone scintigraphy is very sensitive for stress reactions, including subchondral stress fractures, in most cases it lacks specificity, with synovitis, arthritis, degenerative joint disease, stress reactions, and tumor appearing similar. Supplemental imaging with MRI may be necessary for conclusive diagnosis or to avoid false positives [66]. Because planar bone scintigraphy is often nonspecific and supplemental imaging is frequently required, there is consensus in the literature that cross-sectional imaging should supersede planar bone scintigraphy as the imaging of choice for suspected stress fractures when the radiograph is negative [31]. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. Stress (Fatigue-Insufficiency) Fracture CT Area of Interest Without IV Contrast CT is not supported as the next imaging study for suspected subchondral stress fractures following radiographs but may offer an adjunctive role when other imaging modalities are equivocal [22]. Although superior to radiography, it is less sensitive than nuclear scintigraphy or MRI [23]. The value of CT in the setting of suspected subchondral stress fracture primarily lies in detection of articular surface collapse and sclerosis that could indicate secondary necrosis. CT is useful in cases in which MRI results are equivocal.

69435

acrac_69435_12

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. MRI Area of Interest Without IV Contrast MRI is beneficial after initial negative radiographs to prevent delayed diagnosis. MRI has excellent sensitivity and allows for definitive diagnosis. Radiography Area of Interest Repeat In 10-14 Days In general, follow-up radiographic examination has increased sensitivity compared to initial radiographs [43]. However, subchondral insufficiency fractures are typically radiographically occult until collapse or flattening of the articular surface occurs, at which point morbidity is significantly increased. Therefore, MRI without IV contrast should be considered as the next imaging study after initial negative radiographs to prevent delay in diagnosis and preventative treatment. US Area of Interest US does not allow evaluation of subchondral bone and so provides no benefit in this scenario. Variant 6: Adult. Positive stress fracture on radiographs, excluding vertebrae. Need for determining extent (ie, for surgical planning, return to activity) or associated complication (ie, osteonecrosis or delayed healing). Next imaging study. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, ribs, sacrum, shoulder, or wrist. After a diagnosis of stress fracture is made, additional imaging is typically not needed. Most patients are followed clinically until they are pain free, at which time they can increase activity in a controlled manner [14]. Fractures in the long bones may be followed up by radiography, CT, MRI, or a combination thereof as needed to determine full extent of involvement.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. MRI Area of Interest Without and With IV Contrast There is no relevant literature to support the use of MRI area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. MRI Area of Interest Without IV Contrast MRI is beneficial after initial negative radiographs to prevent delayed diagnosis. MRI has excellent sensitivity and allows for definitive diagnosis. Radiography Area of Interest Repeat In 10-14 Days In general, follow-up radiographic examination has increased sensitivity compared to initial radiographs [43]. However, subchondral insufficiency fractures are typically radiographically occult until collapse or flattening of the articular surface occurs, at which point morbidity is significantly increased. Therefore, MRI without IV contrast should be considered as the next imaging study after initial negative radiographs to prevent delay in diagnosis and preventative treatment. US Area of Interest US does not allow evaluation of subchondral bone and so provides no benefit in this scenario. Variant 6: Adult. Positive stress fracture on radiographs, excluding vertebrae. Need for determining extent (ie, for surgical planning, return to activity) or associated complication (ie, osteonecrosis or delayed healing). Next imaging study. Area of Interest: pelvis, ankle, elbow, femur, foot, forearm, hand, hip, humerus, knee, leg tib/fib, ribs, sacrum, shoulder, or wrist. After a diagnosis of stress fracture is made, additional imaging is typically not needed. Most patients are followed clinically until they are pain free, at which time they can increase activity in a controlled manner [14]. Fractures in the long bones may be followed up by radiography, CT, MRI, or a combination thereof as needed to determine full extent of involvement.

69435

acrac_69435_13

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Occasionally, once activity/weightbearing is increased, an unexpected incomplete response to conservative therapy becomes evident with the return of pretreatment symptoms. In this situation, it is recommended that follow-up imaging be performed as well as re-evaluation of the original imaging studies to determine whether the true etiology of pain was obscured or simply misdiagnosed. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT is useful in identifying possible etiologies in delayed healing after conservative therapy for suspected stress fracture, such as osteoid osteoma or suspected completion of fracture. Stress (Fatigue-Insufficiency) Fracture MRI Area of Interest Without and With IV Contrast MRI with IV contrast may be useful in identifying complications of stress fracture such as osteonecrosis or in suspected osteoid osteoma or tumor causing persistent symptoms or delayed healing after conservative therapy for suspected stress fracture. MRI Area of Interest Without IV Contrast MRI is useful in identifying complications of stress fracture such as osteonecrosis or in suspected osteoid osteoma or tumor causing persistent symptoms or delayed healing after conservative therapy for suspected stress fracture. In athletes, MRI can be used to predict time to return to play on initial diagnosis.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Occasionally, once activity/weightbearing is increased, an unexpected incomplete response to conservative therapy becomes evident with the return of pretreatment symptoms. In this situation, it is recommended that follow-up imaging be performed as well as re-evaluation of the original imaging studies to determine whether the true etiology of pain was obscured or simply misdiagnosed. CT Area of Interest With IV Contrast There is no relevant literature to support the use of CT area of interest with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without and With IV Contrast There is no relevant literature to support the use of CT area of interest without and with IV contrast because it does not provide added information over noncontrast imaging with regard to stress injury. CT Area of Interest Without IV Contrast CT is useful in identifying possible etiologies in delayed healing after conservative therapy for suspected stress fracture, such as osteoid osteoma or suspected completion of fracture. Stress (Fatigue-Insufficiency) Fracture MRI Area of Interest Without and With IV Contrast MRI with IV contrast may be useful in identifying complications of stress fracture such as osteonecrosis or in suspected osteoid osteoma or tumor causing persistent symptoms or delayed healing after conservative therapy for suspected stress fracture. MRI Area of Interest Without IV Contrast MRI is useful in identifying complications of stress fracture such as osteonecrosis or in suspected osteoid osteoma or tumor causing persistent symptoms or delayed healing after conservative therapy for suspected stress fracture. In athletes, MRI can be used to predict time to return to play on initial diagnosis.

69435

acrac_69435_14

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs

Fredericson et al [71] retrospectively correlated return to activity with an MRI grading system based on the pattern of periosteal and marrow edema on T1-weighted and fat-suppressed T2-weighted sequences. Similar findings were confirmed in other studies [13,72,73], including that the finding of abnormal cortical signal intensity or a fracture line was of prognostic value [73] and that MRI performed better in predicting return to activity than radiographs, bone scintigraphy, or CT [72,74]. A recent prospective study in university athletes found that MRI grading severity, total-body bone mineral density evaluated by dual-energy X-ray absorptiometry, and location of injury (ie, cortical or trabecular bone) were important variables for predicting time to full return to sport [42]. In this study, periosteal edema as described by Fredericson et al [71] was not associated with return to sport. Using the modified grading scale and a multiple regression model, for every 1-unit increase in MRI grade, the time to full return to sport increased by approximately 48 days [42]. Furthermore, trabecular stress injuries (eg, femur neck and pubic bone) were associated with a longer time to return to sport than cortical bone stress injuries. In addition, decreased bone mineral density leads to increased time to return to sport. Therefore, bone mineral density provides additional diagnostic and prognostic information [42]. The model of MRI grade, trabecular versus cortical bone site, and total-body bone mineral density accounted for 68% of the variation in time to return to sport [42]. Although further studies are needed, optimization of bone mass may reduce risk of sustaining stress injuries or possibly reduce recovery time in athletes with these injuries.

Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Fredericson et al [71] retrospectively correlated return to activity with an MRI grading system based on the pattern of periosteal and marrow edema on T1-weighted and fat-suppressed T2-weighted sequences. Similar findings were confirmed in other studies [13,72,73], including that the finding of abnormal cortical signal intensity or a fracture line was of prognostic value [73] and that MRI performed better in predicting return to activity than radiographs, bone scintigraphy, or CT [72,74]. A recent prospective study in university athletes found that MRI grading severity, total-body bone mineral density evaluated by dual-energy X-ray absorptiometry, and location of injury (ie, cortical or trabecular bone) were important variables for predicting time to full return to sport [42]. In this study, periosteal edema as described by Fredericson et al [71] was not associated with return to sport. Using the modified grading scale and a multiple regression model, for every 1-unit increase in MRI grade, the time to full return to sport increased by approximately 48 days [42]. Furthermore, trabecular stress injuries (eg, femur neck and pubic bone) were associated with a longer time to return to sport than cortical bone stress injuries. In addition, decreased bone mineral density leads to increased time to return to sport. Therefore, bone mineral density provides additional diagnostic and prognostic information [42]. The model of MRI grade, trabecular versus cortical bone site, and total-body bone mineral density accounted for 68% of the variation in time to return to sport [42]. Although further studies are needed, optimization of bone mass may reduce risk of sustaining stress injuries or possibly reduce recovery time in athletes with these injuries.

69435

acrac_69462_0

Multiple Gestations

Introduction/Background The incidence of twin pregnancies has been rising, largely attributable to the increasing use of artificial reproductive techniques [1]. Compared with singletons, twin pregnancies carry a higher risk of complications [2]. These include maternal hypertensive disorders, growth disturbances, preterm labor, premature rupture of membranes, and other conditions, some of which are unique to monochorionic (MC) twins such as twin-twin transfusion syndrome (TTTS) [3-5]. Compared with singletons, twins face an approximately 5-fold increase in fetal death and a 7-fold increase in neonatal death, primarily due to complications of prematurity [2]. Multiple gestations are also at a higher risk for congenital anomalies, placenta previa, and vasa previa. Importantly, chorionicity determines the prognosis of multiple gestations [2]. People carrying twin or higher-order multiple pregnancies will typically undergo more ultrasound (US) examinations than those carrying singletons [9]. Most will, at minimum, undergo a first trimester dating scan, a nuchal translucency (NT) scan at 11 to 14 weeks, an anatomy scan at 18 to 22 weeks, and 1 or more scans in the third trimester to assess growth. MC pregnancies undergo more frequent follow-up, influenced by the presence of complications and institutional practice [2,9,13]. Some of these high-risk pregnancies will be candidates for fetal intervention. Special Imaging Considerations First trimester fetal anatomy evaluation and fetal echocardiography are available at many institutions [14-16]. Advancement of US technology has allowed improved imaging at earlier gestational ages making this feasible. Indications for detailed first trimester obstetric US were summarized by American Institute of Ultrasound in Medicine (AIUM) and endorsed by other key societies, with relevant International Classification of Diseases, 10th Revision (ICD-10) codes provided [15,16]. Reprint requests to: [email protected]

Multiple Gestations. Introduction/Background The incidence of twin pregnancies has been rising, largely attributable to the increasing use of artificial reproductive techniques [1]. Compared with singletons, twin pregnancies carry a higher risk of complications [2]. These include maternal hypertensive disorders, growth disturbances, preterm labor, premature rupture of membranes, and other conditions, some of which are unique to monochorionic (MC) twins such as twin-twin transfusion syndrome (TTTS) [3-5]. Compared with singletons, twins face an approximately 5-fold increase in fetal death and a 7-fold increase in neonatal death, primarily due to complications of prematurity [2]. Multiple gestations are also at a higher risk for congenital anomalies, placenta previa, and vasa previa. Importantly, chorionicity determines the prognosis of multiple gestations [2]. People carrying twin or higher-order multiple pregnancies will typically undergo more ultrasound (US) examinations than those carrying singletons [9]. Most will, at minimum, undergo a first trimester dating scan, a nuchal translucency (NT) scan at 11 to 14 weeks, an anatomy scan at 18 to 22 weeks, and 1 or more scans in the third trimester to assess growth. MC pregnancies undergo more frequent follow-up, influenced by the presence of complications and institutional practice [2,9,13]. Some of these high-risk pregnancies will be candidates for fetal intervention. Special Imaging Considerations First trimester fetal anatomy evaluation and fetal echocardiography are available at many institutions [14-16]. Advancement of US technology has allowed improved imaging at earlier gestational ages making this feasible. Indications for detailed first trimester obstetric US were summarized by American Institute of Ultrasound in Medicine (AIUM) and endorsed by other key societies, with relevant International Classification of Diseases, 10th Revision (ICD-10) codes provided [15,16]. Reprint requests to: [email protected]

69462

acrac_69462_1

Multiple Gestations

Multiple Gestations Fetal Doppler can include umbilical artery (UA), middle cerebral artery (MCA), and ductus venosus. At some institutions, all 3 are performed together as an obstetric Doppler evaluation. Ductus venosus evaluation is performed as a part of fetal echocardiography evaluation. Fetal imaging with MRI is being increasingly used for pregnancies complicated by congenital anomalies or complications related to MC gestations [17,18]. Both neurologic and nonneurologic indications exist for fetal imaging. In MC twins, fetal MRI is helpful for assessing intracranial injury that may occur following spontaneous single fetal demise or after an in utero intervention such as laser ablation of intertwin vascular connections [18,19]. Details on risk to the fetus, guidelines on screening for pregnancy, minimizing radiation exposure, and risk assessment can be found in the ACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Adolescents and Women with Ionizing Radiation [20]. Gadolinium contrast is a relatively contraindicated in pregnancy, which is discussed in detail in the ACR Manual on Contrast Media [21] and the ACR Gadolinium Pregnancy Screening Statement [22]. Most importantly, there are currently no established indications for using gadolinium for MRI evaluation of twin pregnancy or fetal conditions, in general. OR Discussion of Procedures by Variant The variants discussed are presented in approximate order of gestational age. This discussion is almost entirely focused on twin pregnancies because twins represent 98% of multiple gestations, and the vast majority of data relate to twins. It is recognized that higher risks occur in the setting of triplets and higher-order multiples [23]. Variant 1: Known or suspected multiple gestations. Monochorionic or dichorionic. First trimester. Initial imaging. In this variant, the patient is clinically known or suspected to be pregnant with twins or higher order multiples.

Multiple Gestations. Multiple Gestations Fetal Doppler can include umbilical artery (UA), middle cerebral artery (MCA), and ductus venosus. At some institutions, all 3 are performed together as an obstetric Doppler evaluation. Ductus venosus evaluation is performed as a part of fetal echocardiography evaluation. Fetal imaging with MRI is being increasingly used for pregnancies complicated by congenital anomalies or complications related to MC gestations [17,18]. Both neurologic and nonneurologic indications exist for fetal imaging. In MC twins, fetal MRI is helpful for assessing intracranial injury that may occur following spontaneous single fetal demise or after an in utero intervention such as laser ablation of intertwin vascular connections [18,19]. Details on risk to the fetus, guidelines on screening for pregnancy, minimizing radiation exposure, and risk assessment can be found in the ACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Adolescents and Women with Ionizing Radiation [20]. Gadolinium contrast is a relatively contraindicated in pregnancy, which is discussed in detail in the ACR Manual on Contrast Media [21] and the ACR Gadolinium Pregnancy Screening Statement [22]. Most importantly, there are currently no established indications for using gadolinium for MRI evaluation of twin pregnancy or fetal conditions, in general. OR Discussion of Procedures by Variant The variants discussed are presented in approximate order of gestational age. This discussion is almost entirely focused on twin pregnancies because twins represent 98% of multiple gestations, and the vast majority of data relate to twins. It is recognized that higher risks occur in the setting of triplets and higher-order multiples [23]. Variant 1: Known or suspected multiple gestations. Monochorionic or dichorionic. First trimester. Initial imaging. In this variant, the patient is clinically known or suspected to be pregnant with twins or higher order multiples.

69462

acrac_69462_2

Multiple Gestations

Multiple gestation pregnancies are most often detected in the first trimester. Sometimes a point-of-care US may have been performed. At the time of this evaluation, the most important assessments include ascertaining the location of the pregnancy, identifying the number of gestational sacs, and determining the chorionicity and amnionicity [24]. An NT sonogram performed between 11 and 14 weeks has been incorporated into many practices. If not previously imagined, multiple gestations can sometimes be detected on that examination. MRI Fetal Without and With IV Contrast Fetal MRI without and with intravenous (IV) contrast is not useful as an initial imaging modality for the evaluation of known or suspected multiple gestations. Gadolinium contrast administration is avoided during pregnancy and is used only in exceptional circumstances. There is no relevant literature regarding the use of fetal MRI without and with IV contrast in these patients. Sometimes a gestational sac may be identified incidentally during imaging for other reasons. These patients are usually referred to US for further evaluation. MRI Fetal Without IV Contrast Fetal MRI without IV contrast is not useful as an initial imaging modality for the evaluation of known or suspected multiple gestations. There is no relevant literature regarding the use of fetal MRI without IV contrast in these patients. Sometimes a gestational sac may be identified incidentally during imaging for other reasons. These patients are usually referred to US for further evaluation. US Assessment for TTTS Complications affecting MC twins such as TTTS and other conditions related to a single shared placenta usually develop after 14 weeks and do not occur in the first trimester [9]. Hence, US assessment for TTTS is not useful in the first trimester [9]. However, embryonic crown-rump length (CRL) measurements are performed during Multiple Gestations transabdominal and transvaginal imaging of the pregnant uterus.

Multiple Gestations. Multiple gestation pregnancies are most often detected in the first trimester. Sometimes a point-of-care US may have been performed. At the time of this evaluation, the most important assessments include ascertaining the location of the pregnancy, identifying the number of gestational sacs, and determining the chorionicity and amnionicity [24]. An NT sonogram performed between 11 and 14 weeks has been incorporated into many practices. If not previously imagined, multiple gestations can sometimes be detected on that examination. MRI Fetal Without and With IV Contrast Fetal MRI without and with intravenous (IV) contrast is not useful as an initial imaging modality for the evaluation of known or suspected multiple gestations. Gadolinium contrast administration is avoided during pregnancy and is used only in exceptional circumstances. There is no relevant literature regarding the use of fetal MRI without and with IV contrast in these patients. Sometimes a gestational sac may be identified incidentally during imaging for other reasons. These patients are usually referred to US for further evaluation. MRI Fetal Without IV Contrast Fetal MRI without IV contrast is not useful as an initial imaging modality for the evaluation of known or suspected multiple gestations. There is no relevant literature regarding the use of fetal MRI without IV contrast in these patients. Sometimes a gestational sac may be identified incidentally during imaging for other reasons. These patients are usually referred to US for further evaluation. US Assessment for TTTS Complications affecting MC twins such as TTTS and other conditions related to a single shared placenta usually develop after 14 weeks and do not occur in the first trimester [9]. Hence, US assessment for TTTS is not useful in the first trimester [9]. However, embryonic crown-rump length (CRL) measurements are performed during Multiple Gestations transabdominal and transvaginal imaging of the pregnant uterus.

69462

acrac_69462_3

Multiple Gestations

If there is an intertwin discrepancy in CRL or NT measurements, this may be an early marker for TTTS [9]. US Cervix Transvaginal Transvaginal US (TVUS) of the cervix can be performed to confirm that the cervix is closed and is done along with TVUS of the pregnant uterus. An open cervix indicates a high risk for miscarriage. Cervical length measurement is not recommended in the first trimester. In studies specifically evaluating twin pregnancies, routine TVUS assessment of cervical length in the first trimester (as a component of standard management of low-risk twins) has not been shown to predict preterm labor or to be associated with improved outcomes [25,26]. In an asymptomatic and low-risk twin population, a single transvaginal cervical length between 16 and 20 weeks was not predictive of spontaneous preterm birth before 34 weeks, and hence cervical length measurement in the first trimester is of limited value [25,26]. US Duplex Doppler Fetal Middle Cerebral Artery US Doppler of the fetal MCA is not useful as an initial imaging modality for the evaluation of known or suspected multiple gestations. Fetal organogenesis is usually completed by 11 to 12 weeks, at which time identifiable fetal anatomic parts have developed. Until organogenesis completion around 12 weeks, a separate fetal MCA is not identifiable, and hence fetal MCA Doppler cannot be performed. Hence, this examination is not useful in the first trimester. US Duplex Doppler Fetal Umbilical Artery US duplex Doppler of the fetal UA is not useful as an initial imaging modality for the evaluation of known or suspected multiple gestations [9]. In the early first trimester, an identifiable UA cannot reliably be assessed. An identifiable UA is present in the late first trimester; however, there is still no role for UA assessment in the first trimester [9]. US Echocardiography Fetal US echocardiography has no role in the initial imaging in the first trimester [9].

Multiple Gestations. If there is an intertwin discrepancy in CRL or NT measurements, this may be an early marker for TTTS [9]. US Cervix Transvaginal Transvaginal US (TVUS) of the cervix can be performed to confirm that the cervix is closed and is done along with TVUS of the pregnant uterus. An open cervix indicates a high risk for miscarriage. Cervical length measurement is not recommended in the first trimester. In studies specifically evaluating twin pregnancies, routine TVUS assessment of cervical length in the first trimester (as a component of standard management of low-risk twins) has not been shown to predict preterm labor or to be associated with improved outcomes [25,26]. In an asymptomatic and low-risk twin population, a single transvaginal cervical length between 16 and 20 weeks was not predictive of spontaneous preterm birth before 34 weeks, and hence cervical length measurement in the first trimester is of limited value [25,26]. US Duplex Doppler Fetal Middle Cerebral Artery US Doppler of the fetal MCA is not useful as an initial imaging modality for the evaluation of known or suspected multiple gestations. Fetal organogenesis is usually completed by 11 to 12 weeks, at which time identifiable fetal anatomic parts have developed. Until organogenesis completion around 12 weeks, a separate fetal MCA is not identifiable, and hence fetal MCA Doppler cannot be performed. Hence, this examination is not useful in the first trimester. US Duplex Doppler Fetal Umbilical Artery US duplex Doppler of the fetal UA is not useful as an initial imaging modality for the evaluation of known or suspected multiple gestations [9]. In the early first trimester, an identifiable UA cannot reliably be assessed. An identifiable UA is present in the late first trimester; however, there is still no role for UA assessment in the first trimester [9]. US Echocardiography Fetal US echocardiography has no role in the initial imaging in the first trimester [9].

69462

acrac_69462_4

Multiple Gestations

US Pregnant Uterus Biophysical Profile Biophysical profile (BPP) is performed in the second and third trimesters, and there is no role for this in the first trimester. US Pregnant Uterus Transabdominal In the first trimester, the main goal of imaging is to confirm the presence and location of the gestational sacs, determine chorionicity and amnionicity, provide pregnancy dating, and document embryonic or fetal cardiac activity [9]. This is accomplished using transabdominal and TVUS. Once the in utero location of the gestational sac(s) is confirmed, recognition of possible multiple pregnancy is made and gestational age is determined [9]. Gestational age assessment is most accurate at the first US imaging and can be done using mean sac diameter or CRL measurements. In multiple gestations, all attempts should be made to establish the chorionicity and amnionicity at the earliest imaging encounter [9]. TVUS has the highest accuracy for this assessment. In a DC diamniotic gestation, 2 separate gestation sacs each with surrounding echogenic chorionic reactions are identified. A single gestation sac with peripheral chorionic reaction is seen with MC multiple gestations. The presence of thin intertwin membrane corresponds to diamniotic pregnancy. Very early on, the amnion may not yet have formed or be visible. Thus, lack of identification of an intertwin membrane does not necessarily indicate monoamnionicity. The intertwin membrane is typically identified by 10 weeks on TVUS. Although it has been suggested that the number of yolk sacs can be used as an indicator for assessing amnionicity, this determination can sometimes be erroneous [27]. Hence, attempt should be made to demonstrate a thin intertwin membrane as an indication of diamniotic pregnancy, which can more often be achieved by TVUS imaging or at the next US examination [9,27].

Multiple Gestations. US Pregnant Uterus Biophysical Profile Biophysical profile (BPP) is performed in the second and third trimesters, and there is no role for this in the first trimester. US Pregnant Uterus Transabdominal In the first trimester, the main goal of imaging is to confirm the presence and location of the gestational sacs, determine chorionicity and amnionicity, provide pregnancy dating, and document embryonic or fetal cardiac activity [9]. This is accomplished using transabdominal and TVUS. Once the in utero location of the gestational sac(s) is confirmed, recognition of possible multiple pregnancy is made and gestational age is determined [9]. Gestational age assessment is most accurate at the first US imaging and can be done using mean sac diameter or CRL measurements. In multiple gestations, all attempts should be made to establish the chorionicity and amnionicity at the earliest imaging encounter [9]. TVUS has the highest accuracy for this assessment. In a DC diamniotic gestation, 2 separate gestation sacs each with surrounding echogenic chorionic reactions are identified. A single gestation sac with peripheral chorionic reaction is seen with MC multiple gestations. The presence of thin intertwin membrane corresponds to diamniotic pregnancy. Very early on, the amnion may not yet have formed or be visible. Thus, lack of identification of an intertwin membrane does not necessarily indicate monoamnionicity. The intertwin membrane is typically identified by 10 weeks on TVUS. Although it has been suggested that the number of yolk sacs can be used as an indicator for assessing amnionicity, this determination can sometimes be erroneous [27]. Hence, attempt should be made to demonstrate a thin intertwin membrane as an indication of diamniotic pregnancy, which can more often be achieved by TVUS imaging or at the next US examination [9,27].

69462

acrac_69462_5

Multiple Gestations

Authors have reported significant correlation between intertwin CRL discrepancy and outcomes including birthweight discordance, small for gestational age birth weight, preterm delivery, chromosomal abnormalities, structural anomalies, and spontaneous fetal loss [29-32]. Severe CRL discordance (>16%) can be associated with Multiple Gestations US Pregnant Uterus Transvaginal In addition to transabdominal US of the pregnant uterus, TVUS can be performed, especially earlier in gestation, to confirm the number of sacs, to assess chorionicity and amnionicity [24]. When an intertwin membrane is not seen transabdominally, TVUS can be attempted because of superior resolution [9]. Variant 2: Multiple gestations. Monochorionic or dichorionic. First trimester. First trimester ultrasound performed. Next imaging study. In this variant, the patient is known to be carrying a multiple gestation pregnancy and is in the first trimester. The chorionicity has likely been established at a prior US. Often, the amnionicity has also been identified; however, in some cases, definitive confirmation of amnionicity needs to be done. This can be achieved by demonstrating the intertwin membrane at the next imaging study. NT US measurements and first trimester anatomy screening evaluation can be performed at the next imaging study [9,14]. NT measurements for twins are specific screening unique to each twin, whereas cell-free DNA testing techniques cannot separate the genetic information specific to each twin. Documentation of the presence of embryonic cardiac motion and assessment of complications such as early pregnancy failure or subchorionic hemorrhage can also occur. MRI Fetal Without and With IV Contrast Fetal MRI without and with IV contrast is not useful as a next imaging study for the evaluation of known or suspected multiple gestations. There is no relevant literature regarding the use of fetal MRI without and with IV contrast for evaluation of patients with multiple gestations in the first trimester.

Multiple Gestations. Authors have reported significant correlation between intertwin CRL discrepancy and outcomes including birthweight discordance, small for gestational age birth weight, preterm delivery, chromosomal abnormalities, structural anomalies, and spontaneous fetal loss [29-32]. Severe CRL discordance (>16%) can be associated with Multiple Gestations US Pregnant Uterus Transvaginal In addition to transabdominal US of the pregnant uterus, TVUS can be performed, especially earlier in gestation, to confirm the number of sacs, to assess chorionicity and amnionicity [24]. When an intertwin membrane is not seen transabdominally, TVUS can be attempted because of superior resolution [9]. Variant 2: Multiple gestations. Monochorionic or dichorionic. First trimester. First trimester ultrasound performed. Next imaging study. In this variant, the patient is known to be carrying a multiple gestation pregnancy and is in the first trimester. The chorionicity has likely been established at a prior US. Often, the amnionicity has also been identified; however, in some cases, definitive confirmation of amnionicity needs to be done. This can be achieved by demonstrating the intertwin membrane at the next imaging study. NT US measurements and first trimester anatomy screening evaluation can be performed at the next imaging study [9,14]. NT measurements for twins are specific screening unique to each twin, whereas cell-free DNA testing techniques cannot separate the genetic information specific to each twin. Documentation of the presence of embryonic cardiac motion and assessment of complications such as early pregnancy failure or subchorionic hemorrhage can also occur. MRI Fetal Without and With IV Contrast Fetal MRI without and with IV contrast is not useful as a next imaging study for the evaluation of known or suspected multiple gestations. There is no relevant literature regarding the use of fetal MRI without and with IV contrast for evaluation of patients with multiple gestations in the first trimester.

69462

acrac_69462_6

Multiple Gestations

MRI Fetal Without IV Contrast Fetal MRI without IV contrast is not useful as a next imaging study for the evaluation of known or suspected multiple gestations. There is no relevant literature regarding the use of fetal MRI without IV contrast for the evaluation of patients with multiple gestations in the first trimester. US Cervix Transvaginal US cervix transvaginal can be performed as the next imaging study to assess the cervix. In studies specifically evaluating low-risk twin pregnancies, routine TVUS assessment of cervical length in the first trimester (as a component of standard management) has not been shown to predict preterm labor or to be associated with improved outcomes [25,26]. US Duplex Doppler Fetal Middle Cerebral Artery US Doppler of the fetal MCA is not useful as the next imaging study for the evaluation of known or suspected multiple gestations. Early in pregnancy, a discrete fetal MCA is not identifiable, and fetal MCA Doppler cannot be performed. Hence, this examination is not useful in the first trimester [9]. US Duplex Doppler Fetal Umbilical Artery US Doppler of the fetal UA is not routinely used as the next imaging study for the evaluation of known or suspected multiple gestations. An identifiable UA is present in the late first trimester [9]. There is no established role for UA assessment at this gestational age, and hence this examination is not indicated in the first trimester. Multiple Gestations US Echocardiography Fetal US echocardiography can be performed in the first trimester between 12 weeks 0 days and 13 weeks 6 days. Indications for detailed first trimester obstetric US and fetal echocardiography were summarized by AIUM and endorsed by other key societies and include both maternal and fetal indications.

Multiple Gestations. MRI Fetal Without IV Contrast Fetal MRI without IV contrast is not useful as a next imaging study for the evaluation of known or suspected multiple gestations. There is no relevant literature regarding the use of fetal MRI without IV contrast for the evaluation of patients with multiple gestations in the first trimester. US Cervix Transvaginal US cervix transvaginal can be performed as the next imaging study to assess the cervix. In studies specifically evaluating low-risk twin pregnancies, routine TVUS assessment of cervical length in the first trimester (as a component of standard management) has not been shown to predict preterm labor or to be associated with improved outcomes [25,26]. US Duplex Doppler Fetal Middle Cerebral Artery US Doppler of the fetal MCA is not useful as the next imaging study for the evaluation of known or suspected multiple gestations. Early in pregnancy, a discrete fetal MCA is not identifiable, and fetal MCA Doppler cannot be performed. Hence, this examination is not useful in the first trimester [9]. US Duplex Doppler Fetal Umbilical Artery US Doppler of the fetal UA is not routinely used as the next imaging study for the evaluation of known or suspected multiple gestations. An identifiable UA is present in the late first trimester [9]. There is no established role for UA assessment at this gestational age, and hence this examination is not indicated in the first trimester. Multiple Gestations US Echocardiography Fetal US echocardiography can be performed in the first trimester between 12 weeks 0 days and 13 weeks 6 days. Indications for detailed first trimester obstetric US and fetal echocardiography were summarized by AIUM and endorsed by other key societies and include both maternal and fetal indications.

69462

acrac_69462_7

Multiple Gestations

These include but are not limited to previous fetus or child with a congenital, genetic, or chromosomal anomaly; known or suspected fetal abnormality detected by US in the current pregnancy; and fetus at increased risk for a congenital anomaly based on the following: 35 years of age or older at delivery, maternal pregestational diabetes, pregnancy conceived via in vitro fertilization, multiple gestations, teratogen exposure, enlarged NT, positive screening test results for aneuploidy including cell-free DNA screening and serum only, or combined first trimester screening [15,16]. US Pregnant Uterus Biophysical Profile BPP is performed in the second and third trimesters, and there is no role for this in the first trimester. As in singleton pregnancies, increased NT measurements are associated with an increased risk of aneuploidy and structural anomalies; markedly increased NT is associated with a greater risk of subsequent demise [33]. In MC twin pairs, markedly discordant NT can be a marker for early-onset TTTS [37]. However, normal fetal anatomy and karyotype were the most common outcomes among MC diamniotic twins with discordant NTs [38]. Some studies of MC diamniotic twins have shown that NT discordance is more predictive of adverse fetal outcomes than CRL discordance [39]. Others, including Allaf et al [40], found that NT and CRL discordances were not predictive of overall adverse outcomes in MC diamniotic twin pregnancies, although this varies with the severity of discordance. Both parameters (NT and CRL discrepancy) had high negative predictive value; thus, the absence of discordance is reassuring [39]. US Pregnant Uterus Transvaginal As with transabdominal US of the pregnant uterus, a next TVUS study in the first trimester can be performed for confirming cardiac motion, demonstrating the intertwin membrane (if not previously visualized) and NT measurements.

Multiple Gestations. These include but are not limited to previous fetus or child with a congenital, genetic, or chromosomal anomaly; known or suspected fetal abnormality detected by US in the current pregnancy; and fetus at increased risk for a congenital anomaly based on the following: 35 years of age or older at delivery, maternal pregestational diabetes, pregnancy conceived via in vitro fertilization, multiple gestations, teratogen exposure, enlarged NT, positive screening test results for aneuploidy including cell-free DNA screening and serum only, or combined first trimester screening [15,16]. US Pregnant Uterus Biophysical Profile BPP is performed in the second and third trimesters, and there is no role for this in the first trimester. As in singleton pregnancies, increased NT measurements are associated with an increased risk of aneuploidy and structural anomalies; markedly increased NT is associated with a greater risk of subsequent demise [33]. In MC twin pairs, markedly discordant NT can be a marker for early-onset TTTS [37]. However, normal fetal anatomy and karyotype were the most common outcomes among MC diamniotic twins with discordant NTs [38]. Some studies of MC diamniotic twins have shown that NT discordance is more predictive of adverse fetal outcomes than CRL discordance [39]. Others, including Allaf et al [40], found that NT and CRL discordances were not predictive of overall adverse outcomes in MC diamniotic twin pregnancies, although this varies with the severity of discordance. Both parameters (NT and CRL discrepancy) had high negative predictive value; thus, the absence of discordance is reassuring [39]. US Pregnant Uterus Transvaginal As with transabdominal US of the pregnant uterus, a next TVUS study in the first trimester can be performed for confirming cardiac motion, demonstrating the intertwin membrane (if not previously visualized) and NT measurements.

69462

acrac_69462_8

Multiple Gestations

TVUS imaging is routinely performed in some institutions or can be done as needed, when the transabdominal evaluation is considered incomplete or suboptimal. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in the second trimester anatomy evaluation. Gadolinium contrast is usually not administered for fetal indications. Multiple Gestations MRI Fetal Without IV Contrast MRI fetal without IV contrast does not have a role in the initial second trimester anatomy evaluation. MRI fetal without IV contrast can be considered for multiple gestations if an abnormality is noted in the second trimester anatomy US. It can also be considered when maternal factors, such as soft tissue attenuation, limit sonographic evaluation of the fetus. In all cases, anatomy evaluation with MRI without IV contrast is performed after an US examination has been performed. US Assessment for TTTS With very rare exceptions, DC twins with separate placentas do not develop TTTS or other complications associated with placental sharing and vascular connections. Hence, US assessment for TTTS is not useful for DC or multichorionic twins. US Duplex Doppler Fetal Middle Cerebral Artery US duplex Doppler fetal MCA is not useful for complications of multiple pregnancies at the second trimester anatomy scan. If there is a risk for fetal anemia or if hydrops is noted during evaluation, fetal MCA Doppler can be performed and interpreted using established nomograms [45]. US Duplex Doppler Fetal Umbilical Artery US duplex Doppler fetal UA is not useful for complications of multiple pregnancies at the second trimester anatomy scan. However, if growth restriction is noted during evaluation, fetal UA Doppler can be performed.

Multiple Gestations. TVUS imaging is routinely performed in some institutions or can be done as needed, when the transabdominal evaluation is considered incomplete or suboptimal. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in the second trimester anatomy evaluation. Gadolinium contrast is usually not administered for fetal indications. Multiple Gestations MRI Fetal Without IV Contrast MRI fetal without IV contrast does not have a role in the initial second trimester anatomy evaluation. MRI fetal without IV contrast can be considered for multiple gestations if an abnormality is noted in the second trimester anatomy US. It can also be considered when maternal factors, such as soft tissue attenuation, limit sonographic evaluation of the fetus. In all cases, anatomy evaluation with MRI without IV contrast is performed after an US examination has been performed. US Assessment for TTTS With very rare exceptions, DC twins with separate placentas do not develop TTTS or other complications associated with placental sharing and vascular connections. Hence, US assessment for TTTS is not useful for DC or multichorionic twins. US Duplex Doppler Fetal Middle Cerebral Artery US duplex Doppler fetal MCA is not useful for complications of multiple pregnancies at the second trimester anatomy scan. If there is a risk for fetal anemia or if hydrops is noted during evaluation, fetal MCA Doppler can be performed and interpreted using established nomograms [45]. US Duplex Doppler Fetal Umbilical Artery US duplex Doppler fetal UA is not useful for complications of multiple pregnancies at the second trimester anatomy scan. However, if growth restriction is noted during evaluation, fetal UA Doppler can be performed.

69462

acrac_69462_9

Multiple Gestations

US Echocardiography Fetal Multiple gestations are at higher risk for cardiac defects, and echocardiography is very useful in the second trimester. This is particularly relevant for DC twin pregnancies conceived using assisted reproductive technologies because these groups are at increased risk of congenital heart disease [46]. US Pregnant Uterus Biophysical Profile BPP is performed in late second and third trimesters, and there is no role in the first trimester. There is no role for BPP at the time of second trimester anatomy scan. US Pregnant Uterus Transvaginal Transvaginal examination of the pregnant uterus and cervix can be performed as an adjunct for limited transabdominal fetal evaluation. Additional indications include assessment of the cervix and placenta and detection of vasa previa. Typically, TVUS imaging is performed only if transabdominal evaluation is considered suboptimal Multiple Gestations or incomplete and never as the only approach for second trimester anatomy evaluation. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in the second trimester anatomy evaluation. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast does not have a role in the second trimester anatomy evaluation. MRI fetal without IV contrast can be considered for the next imaging after an abnormality is noted on the second trimester anatomy sonogram. It can also be considered when maternal factors such as soft tissue attenuation limit evaluation of the fetus on US. In all cases, anatomy evaluation with MRI without IV contrast is performed after an US has previously been done. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor.

Multiple Gestations. US Echocardiography Fetal Multiple gestations are at higher risk for cardiac defects, and echocardiography is very useful in the second trimester. This is particularly relevant for DC twin pregnancies conceived using assisted reproductive technologies because these groups are at increased risk of congenital heart disease [46]. US Pregnant Uterus Biophysical Profile BPP is performed in late second and third trimesters, and there is no role in the first trimester. There is no role for BPP at the time of second trimester anatomy scan. US Pregnant Uterus Transvaginal Transvaginal examination of the pregnant uterus and cervix can be performed as an adjunct for limited transabdominal fetal evaluation. Additional indications include assessment of the cervix and placenta and detection of vasa previa. Typically, TVUS imaging is performed only if transabdominal evaluation is considered suboptimal Multiple Gestations or incomplete and never as the only approach for second trimester anatomy evaluation. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in the second trimester anatomy evaluation. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast does not have a role in the second trimester anatomy evaluation. MRI fetal without IV contrast can be considered for the next imaging after an abnormality is noted on the second trimester anatomy sonogram. It can also be considered when maternal factors such as soft tissue attenuation limit evaluation of the fetus on US. In all cases, anatomy evaluation with MRI without IV contrast is performed after an US has previously been done. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor.

69462

acrac_69462_10

Multiple Gestations

However, more recent literature has questioned the significance and usefulness of this practice because of a lack of proven effective interventions. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43]. Multiple Gestations Vasa previa and velamentous cord insertion are more commonly present in MC multiple gestations. Both of these conditions are associated with adverse pregnancy outcome and deserve dedicated evaluation at this point in pregnancy [47]. There is also a higher frequency of vasa previa when velamentous cord insertion is found; if overlooked, this may result in acute fetal hemorrhage, distress, and potential demise at the time of delivery. For this reason, examiners should be aware of the possibility of vasa previa, especially in MC pregnancies [49]. US Duplex Doppler Fetal Middle Cerebral Artery Fetal MCA Doppler assessment is performed to detect the presence of TAPS [3,20,50,51]. In contrast to evaluation for TTTS, there are no clear established guidelines addressing whether evaluation for TAPS should be part of routine second trimester anatomy evaluation. This may be optionally considered on a case-by-case basis, for example, when imaging signs of TTTS are present [9]. Some authors are advocating for routine antenatal screening for TAPS in MC gestations [50]. US Duplex Doppler Fetal Umbilical Artery US duplex Doppler fetal UA is essential for second trimester evaluation of MC twins and should be performed at the time of anatomy evaluation [9]. This is helpful for the staging of TTTS, TAPS, and growth discordant twins. US Echocardiography Fetal Multiple gestations are at higher risk for cardiac defects, and an echocardiogram is recommended in the second trimester. The risk of cardiac anomalies has been reported to be 2% in uncomplicated MC twins and 5% in cases of TTTS, particularly among recipient twins [52,53].

Multiple Gestations. However, more recent literature has questioned the significance and usefulness of this practice because of a lack of proven effective interventions. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43]. Multiple Gestations Vasa previa and velamentous cord insertion are more commonly present in MC multiple gestations. Both of these conditions are associated with adverse pregnancy outcome and deserve dedicated evaluation at this point in pregnancy [47]. There is also a higher frequency of vasa previa when velamentous cord insertion is found; if overlooked, this may result in acute fetal hemorrhage, distress, and potential demise at the time of delivery. For this reason, examiners should be aware of the possibility of vasa previa, especially in MC pregnancies [49]. US Duplex Doppler Fetal Middle Cerebral Artery Fetal MCA Doppler assessment is performed to detect the presence of TAPS [3,20,50,51]. In contrast to evaluation for TTTS, there are no clear established guidelines addressing whether evaluation for TAPS should be part of routine second trimester anatomy evaluation. This may be optionally considered on a case-by-case basis, for example, when imaging signs of TTTS are present [9]. Some authors are advocating for routine antenatal screening for TAPS in MC gestations [50]. US Duplex Doppler Fetal Umbilical Artery US duplex Doppler fetal UA is essential for second trimester evaluation of MC twins and should be performed at the time of anatomy evaluation [9]. This is helpful for the staging of TTTS, TAPS, and growth discordant twins. US Echocardiography Fetal Multiple gestations are at higher risk for cardiac defects, and an echocardiogram is recommended in the second trimester. The risk of cardiac anomalies has been reported to be 2% in uncomplicated MC twins and 5% in cases of TTTS, particularly among recipient twins [52,53].

69462

acrac_69462_11

Multiple Gestations

The risk of a structural congenital cardiac anomaly in at least 1 of an MC MA twin pair is 8 times that of a MC diamniotic twin pair [9]. In addition, if 1 MC twin is affected, the risk of the co-twin having a cardiac anomaly is higher. For these reasons, fetal echocardiography should be considered in MC gestations [9]. US Pregnant Uterus Biophysical Profile BPP is performed in late second and third trimesters. There is no role for BPP at the time of second trimester anatomy scan. Placental cord insertion of each twin should be documented in the second trimester. Marginal or velamentous cord insertion are common among MC pregnancies, with velamentous cord insertion present in up to 22% of MC twins [54]. Velamentous cord insertion in MC twins increases the risk of adverse outcome, including small for gestational age and sFGR, lower gestational age at birth, and intrauterine fetal demise [55]. There is also a higher frequency of vasa previa when a velamentous cord insertion is found, especially in MC pregnancies [49]. Velamentous cord insertion in 1 or both twins is associated with increased risk of TTTS, and the risk of discordant growth is determined by both discordance in insertion sites and velamentous cord insertion in 1 twin [56,57]. In a study by Saito et al [57], 27% of twin pairs with abnormal cord insertions (defined as twin pair with velamentous cord insertions and/or marginal cord insertion in 1 or both twins) developed TTTS compared with 7% of twin pairs with normal cord insertions in both. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. US Pregnant Uterus Transvaginal Transvaginal examination of the pregnant uterus and cervix can be performed as an adjunct for limited transabdominal fetal evaluation. Additional indications include assessment of the cervix and placenta and detection of vasa previa.

Multiple Gestations. The risk of a structural congenital cardiac anomaly in at least 1 of an MC MA twin pair is 8 times that of a MC diamniotic twin pair [9]. In addition, if 1 MC twin is affected, the risk of the co-twin having a cardiac anomaly is higher. For these reasons, fetal echocardiography should be considered in MC gestations [9]. US Pregnant Uterus Biophysical Profile BPP is performed in late second and third trimesters. There is no role for BPP at the time of second trimester anatomy scan. Placental cord insertion of each twin should be documented in the second trimester. Marginal or velamentous cord insertion are common among MC pregnancies, with velamentous cord insertion present in up to 22% of MC twins [54]. Velamentous cord insertion in MC twins increases the risk of adverse outcome, including small for gestational age and sFGR, lower gestational age at birth, and intrauterine fetal demise [55]. There is also a higher frequency of vasa previa when a velamentous cord insertion is found, especially in MC pregnancies [49]. Velamentous cord insertion in 1 or both twins is associated with increased risk of TTTS, and the risk of discordant growth is determined by both discordance in insertion sites and velamentous cord insertion in 1 twin [56,57]. In a study by Saito et al [57], 27% of twin pairs with abnormal cord insertions (defined as twin pair with velamentous cord insertions and/or marginal cord insertion in 1 or both twins) developed TTTS compared with 7% of twin pairs with normal cord insertions in both. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. US Pregnant Uterus Transvaginal Transvaginal examination of the pregnant uterus and cervix can be performed as an adjunct for limited transabdominal fetal evaluation. Additional indications include assessment of the cervix and placenta and detection of vasa previa.

69462

acrac_69462_12

Multiple Gestations

Typically, transvaginal imaging is performed only if transabdominal evaluation is considered suboptimal or incomplete and never as the only approach for second trimester anatomy evaluation. If prior history Multiple Gestations of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in growth and antepartum surveillance of DC or multichorionic gestations. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast does not have a role in growth and antepartum surveillance of DC or multichorionic gestations. It is usually reserved for problem-solving when an anatomic abnormality is identified. US Assessment for TTTS DC twins with separate placentas do not develop TTTS or other complications associated with a single shared placenta. Hence, this evaluation is not useful for growth and antepartum surveillance of DC or multichorionic twins. US Cervix Transvaginal US cervix transvaginal evaluation for antepartum surveillance is useful for assessing cervical length, vasa, and placenta previa. Any cervical pathology, such as a myoma or other masses, that may preclude vaginal delivery should also be assessed. Usually, a transabdominal examination is performed first, followed by transvaginal imaging if the initial evaluation is inadequate. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor. However, more recent literature has questioned the significance and usefulness of this practice, recommending against cervical length measurement after 26 weeks. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43].

Multiple Gestations. Typically, transvaginal imaging is performed only if transabdominal evaluation is considered suboptimal or incomplete and never as the only approach for second trimester anatomy evaluation. If prior history Multiple Gestations of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in growth and antepartum surveillance of DC or multichorionic gestations. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast does not have a role in growth and antepartum surveillance of DC or multichorionic gestations. It is usually reserved for problem-solving when an anatomic abnormality is identified. US Assessment for TTTS DC twins with separate placentas do not develop TTTS or other complications associated with a single shared placenta. Hence, this evaluation is not useful for growth and antepartum surveillance of DC or multichorionic twins. US Cervix Transvaginal US cervix transvaginal evaluation for antepartum surveillance is useful for assessing cervical length, vasa, and placenta previa. Any cervical pathology, such as a myoma or other masses, that may preclude vaginal delivery should also be assessed. Usually, a transabdominal examination is performed first, followed by transvaginal imaging if the initial evaluation is inadequate. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor. However, more recent literature has questioned the significance and usefulness of this practice, recommending against cervical length measurement after 26 weeks. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43].

69462

acrac_69462_13

Multiple Gestations

If placenta previa or low-lying placenta has been suggested previously, assessment of the location of placental edge can be performed on surveillance examinations. US Duplex Doppler Fetal Middle Cerebral Artery If there is a risk for fetal anemia or if fetal hydrops is noted during evaluation, fetal MCA Doppler can be performed and interpreted using established nomograms. US duplex Doppler fetal MCA is generally not useful for surveillance of uncomplicated DC or multichorionic gestations. US Duplex Doppler Fetal Umbilical Artery If growth restriction or amniotic fluid abnormalities (oligohydramnios) are noted during antepartum surveillance, fetal UA Doppler can be performed. US duplex Doppler fetal UA is generally not useful for surveillance of uncomplicated DC or multichorionic gestations. US Echocardiography Fetal Echocardiography can be performed for surveillance of DC or multichorionic gestations when cardiac defects or secondary cardiac decompensation is suspected or observed. Uncomplicated DC or multichorionic gestations do not need routine fetal echocardiographic follow-up. US Pregnant Uterus Biophysical Profile BPP can be performed in the late second and third trimesters for assessing fetal well-being. To date, there are insufficient data in the literature to suggest that antenatal surveillance of twins with BPP is beneficial in the setting Multiple Gestations of reactive nonstress test or in the absence of associated risk factors [62,63]. US Pregnant Uterus Transabdominal Transabdominal US of the pregnant uterus remains the mainstay for the evaluation of DC or multichorionic gestations. At each US scan, the following should be assessed: fetal biometry, amniotic fluid volume, and key features of fetal anatomy. Due to variability and SDs in measurements, growth assessment, and biometry are usually performed no more frequently than every 2 weeks. It is suggested that the discordance in estimated fetal weights be calculated and documented at each scan.

Multiple Gestations. If placenta previa or low-lying placenta has been suggested previously, assessment of the location of placental edge can be performed on surveillance examinations. US Duplex Doppler Fetal Middle Cerebral Artery If there is a risk for fetal anemia or if fetal hydrops is noted during evaluation, fetal MCA Doppler can be performed and interpreted using established nomograms. US duplex Doppler fetal MCA is generally not useful for surveillance of uncomplicated DC or multichorionic gestations. US Duplex Doppler Fetal Umbilical Artery If growth restriction or amniotic fluid abnormalities (oligohydramnios) are noted during antepartum surveillance, fetal UA Doppler can be performed. US duplex Doppler fetal UA is generally not useful for surveillance of uncomplicated DC or multichorionic gestations. US Echocardiography Fetal Echocardiography can be performed for surveillance of DC or multichorionic gestations when cardiac defects or secondary cardiac decompensation is suspected or observed. Uncomplicated DC or multichorionic gestations do not need routine fetal echocardiographic follow-up. US Pregnant Uterus Biophysical Profile BPP can be performed in the late second and third trimesters for assessing fetal well-being. To date, there are insufficient data in the literature to suggest that antenatal surveillance of twins with BPP is beneficial in the setting Multiple Gestations of reactive nonstress test or in the absence of associated risk factors [62,63]. US Pregnant Uterus Transabdominal Transabdominal US of the pregnant uterus remains the mainstay for the evaluation of DC or multichorionic gestations. At each US scan, the following should be assessed: fetal biometry, amniotic fluid volume, and key features of fetal anatomy. Due to variability and SDs in measurements, growth assessment, and biometry are usually performed no more frequently than every 2 weeks. It is suggested that the discordance in estimated fetal weights be calculated and documented at each scan.

69462

acrac_69462_14

Multiple Gestations

If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. US Pregnant Uterus Transvaginal Transvaginal examination of the pregnant uterus and cervix can be performed as an adjunct for limited transabdominal fetal evaluation. Additional indications include assessment of the cervix and placenta and detection of vasa previa. Typically, transvaginal imaging is performed only if transabdominal evaluation is considered suboptimal or incomplete. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. Variant 6: Multiple gestations. Monochorionic twins. Growth and antepartum surveillance. In this variant, the patient is known to be pregnant with uncomplicated MC multiple gestation. The fetuses have been demonstrated to share a single placenta. Given the higher incidence of growth disturbance, congenital abnormalities, and complications unique to MC twinning, assessment of growth and surveillance for fetal well- being is indicated. In addition to monitoring fetal size and interval growth, ongoing evaluation includes amniotic fluid assessment and the search for possible development of TTTS, TAPS, or sFGR. Typically, surveillance begins at 16 weeks for MC twins, with fetal biometry performed every 2 to 3 weeks [9,12]. Assessment for potential TTTS or other complications of MC twinning is performed every 2 weeks [9,12]. If there is discordance in fetal size or amniotic fluid volume, shorter interval surveillance may be warranted [13]. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in growth and antepartum surveillance of MC gestations. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast can be useful for antepartum surveillance for a known abnormality.

Multiple Gestations. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. US Pregnant Uterus Transvaginal Transvaginal examination of the pregnant uterus and cervix can be performed as an adjunct for limited transabdominal fetal evaluation. Additional indications include assessment of the cervix and placenta and detection of vasa previa. Typically, transvaginal imaging is performed only if transabdominal evaluation is considered suboptimal or incomplete. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. Variant 6: Multiple gestations. Monochorionic twins. Growth and antepartum surveillance. In this variant, the patient is known to be pregnant with uncomplicated MC multiple gestation. The fetuses have been demonstrated to share a single placenta. Given the higher incidence of growth disturbance, congenital abnormalities, and complications unique to MC twinning, assessment of growth and surveillance for fetal well- being is indicated. In addition to monitoring fetal size and interval growth, ongoing evaluation includes amniotic fluid assessment and the search for possible development of TTTS, TAPS, or sFGR. Typically, surveillance begins at 16 weeks for MC twins, with fetal biometry performed every 2 to 3 weeks [9,12]. Assessment for potential TTTS or other complications of MC twinning is performed every 2 weeks [9,12]. If there is discordance in fetal size or amniotic fluid volume, shorter interval surveillance may be warranted [13]. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in growth and antepartum surveillance of MC gestations. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast can be useful for antepartum surveillance for a known abnormality.

69462

acrac_69462_15

Multiple Gestations

In MC twins, fetal MRI has been used to assess for brain injury that may occur after fetal intervention or following spontaneous in utero demise of a co-twin [17]. This examination is usually not indicated for uncomplicated multiple gestations. In a study by Kawaguchi et al [13], the incidence of unexpected critical complications in patients with MC diamniotic twin pregnancies was significantly lower in those undergoing weekly US, suggesting that weekly sonographic evaluation for patients with MC diamniotic pregnancy may be more effective for the early detection of impending intrauterine fetal death and/or TTTS. US Cervix Transvaginal US cervix transvaginal evaluation for antepartum surveillance is useful for assessing cervical length, vasa, and placenta previa. Any cervical pathology, such as myoma or other masses, that may preclude vaginal delivery should also be assessed. Usually, a transabdominal examination is performed first, followed by transvaginal imaging if the initial evaluation is inadequate. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor. However, more recent literature has questioned the significance and usefulness of this practice, recommending against cervical length measurement after 26 weeks. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43]. If placenta previa or low-lying placenta has been suggested previously, assessment of location of placental edge can be performed. Multiple Gestations US Duplex Doppler Fetal Middle Cerebral Artery Fetal MCA Doppler assessment is performed to detect the presence of TAPS [3,50,51]. This can be done at serial surveillance examinations, with US evaluation for TTTS and UA Doppler interrogation, as frequently as indicated by fetal status [9,50]. US Duplex Doppler Fetal Umbilical Artery US duplex Doppler fetal UA is essential for antepartum surveillance of MC twins.

Multiple Gestations. In MC twins, fetal MRI has been used to assess for brain injury that may occur after fetal intervention or following spontaneous in utero demise of a co-twin [17]. This examination is usually not indicated for uncomplicated multiple gestations. In a study by Kawaguchi et al [13], the incidence of unexpected critical complications in patients with MC diamniotic twin pregnancies was significantly lower in those undergoing weekly US, suggesting that weekly sonographic evaluation for patients with MC diamniotic pregnancy may be more effective for the early detection of impending intrauterine fetal death and/or TTTS. US Cervix Transvaginal US cervix transvaginal evaluation for antepartum surveillance is useful for assessing cervical length, vasa, and placenta previa. Any cervical pathology, such as myoma or other masses, that may preclude vaginal delivery should also be assessed. Usually, a transabdominal examination is performed first, followed by transvaginal imaging if the initial evaluation is inadequate. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor. However, more recent literature has questioned the significance and usefulness of this practice, recommending against cervical length measurement after 26 weeks. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43]. If placenta previa or low-lying placenta has been suggested previously, assessment of location of placental edge can be performed. Multiple Gestations US Duplex Doppler Fetal Middle Cerebral Artery Fetal MCA Doppler assessment is performed to detect the presence of TAPS [3,50,51]. This can be done at serial surveillance examinations, with US evaluation for TTTS and UA Doppler interrogation, as frequently as indicated by fetal status [9,50]. US Duplex Doppler Fetal Umbilical Artery US duplex Doppler fetal UA is essential for antepartum surveillance of MC twins.

69462

acrac_69462_16

Multiple Gestations

This information is critical for the detection and staging of TTTS and for the evaluation of fetuses diagnosed with sFGR [9,42]. US Pregnant Uterus Biophysical Profile BPP can be performed in the third trimester to assess fetal well-being. Frequency of BPP can be determined based on the presence of risk factors and impending complications [53,64]. To date, there are insufficient data in the literature to suggest that antenatal surveillance of twins with BPP is beneficial in the setting of reactive nonstress test or in the absence of associated risk factors [62,63]. US Pregnant Uterus Transabdominal Transabdominal US of the pregnant uterus continues to be the mainstay for the evaluation and surveillance of MC twins. For MC twins, sonographic surveillance usually begins at 16 weeks and is done every 2 weeks thereafter [9,12]. Due to variability and SDs in measurements, growth and biometry is usually performed no more frequently than every 2 weeks. The discordance in estimated fetal weights should be calculated and documented at each scan. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. US Pregnant Uterus Transvaginal Transvaginal examination of the pregnant uterus and cervix can be performed as an adjunct for limited transabdominal fetal evaluation. Additional indications include assessment of the cervix and placenta and detection of vasa previa. Typically, transvaginal imaging is performed only if transabdominal evaluation is considered suboptimal or incomplete. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. Variant 7: Multiple gestations. Dichorionic or multichorionic higher order multiples or monochorionic gestations. Known abnormality or discordance between fetuses (fluid, size, weight). Growth and antepartum surveillance.

Multiple Gestations. This information is critical for the detection and staging of TTTS and for the evaluation of fetuses diagnosed with sFGR [9,42]. US Pregnant Uterus Biophysical Profile BPP can be performed in the third trimester to assess fetal well-being. Frequency of BPP can be determined based on the presence of risk factors and impending complications [53,64]. To date, there are insufficient data in the literature to suggest that antenatal surveillance of twins with BPP is beneficial in the setting of reactive nonstress test or in the absence of associated risk factors [62,63]. US Pregnant Uterus Transabdominal Transabdominal US of the pregnant uterus continues to be the mainstay for the evaluation and surveillance of MC twins. For MC twins, sonographic surveillance usually begins at 16 weeks and is done every 2 weeks thereafter [9,12]. Due to variability and SDs in measurements, growth and biometry is usually performed no more frequently than every 2 weeks. The discordance in estimated fetal weights should be calculated and documented at each scan. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. US Pregnant Uterus Transvaginal Transvaginal examination of the pregnant uterus and cervix can be performed as an adjunct for limited transabdominal fetal evaluation. Additional indications include assessment of the cervix and placenta and detection of vasa previa. Typically, transvaginal imaging is performed only if transabdominal evaluation is considered suboptimal or incomplete. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. Variant 7: Multiple gestations. Dichorionic or multichorionic higher order multiples or monochorionic gestations. Known abnormality or discordance between fetuses (fluid, size, weight). Growth and antepartum surveillance.

69462

acrac_69462_17

Multiple Gestations

In this variant, multiple gestations of all chorionicity and amnionicity have a known abnormality detected on a previous examination and are receiving surveillance imaging. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in growth and antepartum surveillance of MC, DC, or multichorionic gestations. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast can be useful for antepartum surveillance for a known abnormality. In DC and multichorionic twins, this can be indicated for multiple reasons, in particular, to evaluate neurologic, thoracic, and abdominal structural anomalies and associated complications. In MC twins, fetal MRI has been useful in the assessment of intracranial injury that may occur related to TTTS after fetal intervention or following spontaneous in utero demise of a co-twin. Cerebral injury can affect approximately 18% of co-twin survivors after single fetal demise in MC twin pregnancies, and follow-up evaluation of these cases can improve detection rate of such damage [65,66]. MRI evaluation of complicated MC multiple gestations can be useful for estimating neurologic injury associated with TTTS, TAPS, sFGR, and fetal interventions [65]. In a study, postnatal follow-up of all survivors shown to have normal fetal MRI demonstrated normal neurologic outcome, but only 1 of 3 survivors with cerebral lesions at fetal MRI demonstrated normal neurologic outcome [65]. Brain injury of the surviving co-twin after single fetal demise in MC pregnancies is usually of ischemic origin and spares the brainstem and cerebellum [67]. Focal brain lesions are more frequent in pregnancies complicated by TTTS or in Multiple Gestations those in whom an intervention has been performed [67]. Robinson et al [18] showed that MRI provided additional information over a prenatal US in 5 of 33 patients (15%) altering prognosis and patient counseling.

Multiple Gestations. In this variant, multiple gestations of all chorionicity and amnionicity have a known abnormality detected on a previous examination and are receiving surveillance imaging. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in growth and antepartum surveillance of MC, DC, or multichorionic gestations. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast can be useful for antepartum surveillance for a known abnormality. In DC and multichorionic twins, this can be indicated for multiple reasons, in particular, to evaluate neurologic, thoracic, and abdominal structural anomalies and associated complications. In MC twins, fetal MRI has been useful in the assessment of intracranial injury that may occur related to TTTS after fetal intervention or following spontaneous in utero demise of a co-twin. Cerebral injury can affect approximately 18% of co-twin survivors after single fetal demise in MC twin pregnancies, and follow-up evaluation of these cases can improve detection rate of such damage [65,66]. MRI evaluation of complicated MC multiple gestations can be useful for estimating neurologic injury associated with TTTS, TAPS, sFGR, and fetal interventions [65]. In a study, postnatal follow-up of all survivors shown to have normal fetal MRI demonstrated normal neurologic outcome, but only 1 of 3 survivors with cerebral lesions at fetal MRI demonstrated normal neurologic outcome [65]. Brain injury of the surviving co-twin after single fetal demise in MC pregnancies is usually of ischemic origin and spares the brainstem and cerebellum [67]. Focal brain lesions are more frequent in pregnancies complicated by TTTS or in Multiple Gestations those in whom an intervention has been performed [67]. Robinson et al [18] showed that MRI provided additional information over a prenatal US in 5 of 33 patients (15%) altering prognosis and patient counseling.

69462

acrac_69462_18

Multiple Gestations

Additional findings on MRI included occipital lobe infarction, hemispheric injury, dural sinus thrombosis, polymicrogyria, and intraventricular hemorrhage. In this series, US was normal in 2 patients and underrepresented parenchymal injury in the remaining 3 patients [18]. Kocaoglu et al [68] demonstrated that abnormal cerebral imaging findings on MRI due to hypoxic-ischemic injury or hemorrhage can be seen at the beginning of the second trimester and do not correlate with the current US staging system; however, they do correlate with decreased survival. Hence, it has been suggested that fetal MRI-based detection of cerebral abnormalities could be included in the TTTS staging system as an independent risk factor and incorporated in the prenatal evaluation of complicated MC gestations [68]. In a study including 49 MC multiple gestations with single fetal demise, median gestational age at time of co-twin death was 25 weeks and median interval between single fetal loss and live birth was 61 days, with median gestational age at delivery 36 weeks [17]. Severe cerebral injury was diagnosed in 26% of the survivors and was detected antenatally on MRI in 4 of 50 (8%) cases. Abnormal cerebral findings predominantly resulted from hypoxic- ischemic injury resulting in cystic periventricular leukomalacia, MCA infarction, or injury to basal ganglia, thalamus, and/or cortex [17]. Risk factors associated with severe cerebral injury were advanced gestational age at time of single fetal demise, development of TTTS before co-twin loss, and lower gestational age at birth [17]. US Assessment for TTTS DC twins with separate placentas do not typically develop TTTS or other complications associated with a single shared placenta. Hence, this evaluation is not useful for growth and antepartum surveillance of complicated DC or multichorionic twins.

Multiple Gestations. Additional findings on MRI included occipital lobe infarction, hemispheric injury, dural sinus thrombosis, polymicrogyria, and intraventricular hemorrhage. In this series, US was normal in 2 patients and underrepresented parenchymal injury in the remaining 3 patients [18]. Kocaoglu et al [68] demonstrated that abnormal cerebral imaging findings on MRI due to hypoxic-ischemic injury or hemorrhage can be seen at the beginning of the second trimester and do not correlate with the current US staging system; however, they do correlate with decreased survival. Hence, it has been suggested that fetal MRI-based detection of cerebral abnormalities could be included in the TTTS staging system as an independent risk factor and incorporated in the prenatal evaluation of complicated MC gestations [68]. In a study including 49 MC multiple gestations with single fetal demise, median gestational age at time of co-twin death was 25 weeks and median interval between single fetal loss and live birth was 61 days, with median gestational age at delivery 36 weeks [17]. Severe cerebral injury was diagnosed in 26% of the survivors and was detected antenatally on MRI in 4 of 50 (8%) cases. Abnormal cerebral findings predominantly resulted from hypoxic- ischemic injury resulting in cystic periventricular leukomalacia, MCA infarction, or injury to basal ganglia, thalamus, and/or cortex [17]. Risk factors associated with severe cerebral injury were advanced gestational age at time of single fetal demise, development of TTTS before co-twin loss, and lower gestational age at birth [17]. US Assessment for TTTS DC twins with separate placentas do not typically develop TTTS or other complications associated with a single shared placenta. Hence, this evaluation is not useful for growth and antepartum surveillance of complicated DC or multichorionic twins.

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Multiple Gestations

US Cervix Transvaginal US cervix transvaginal evaluation for antepartum surveillance for all multiple gestations is useful for assessing cervical length, vasa, and placenta previa. Any cervical pathology, such as myoma or other masses, that may preclude vaginal delivery should also be assessed. Usually, a transabdominal examination is performed first, followed by transvaginal imaging if the initial evaluation is inadequate. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor. However, more recent literature has questioned the significance and usefulness of this practice, recommending against cervical length measurement after 26 weeks. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43]. If placenta previa or low-lying placenta has been suggested previously, assessment of the location of placental edge can be performed. US Duplex Doppler Fetal Middle Cerebral Artery For DC twins and multichorionic multiples, if there is a risk for fetal anemia or fetal hydrops is noted during surveillance, fetal MCA Doppler can be performed and interpreted using established nomograms. US duplex Multiple Gestations Doppler fetal MCA can be useful for surveillance of complicated DC or multichorionic gestations when there is concern for fetal anemia. Prognostic importance of MCA-PSV for outcome after laser ablation for TTTS has been reported. In a study by Trieu et al [74], there was no correlation between the incidence of elevated MCA-PSV before laser and fetal survival up to 7 days after laser. In contrast, the presence of an MCA-PSV above 1.5 MoM in the former donor twin 48 hours following laser was associated with higher risk for intrauterine fetal demise of the former donor within a week after surgery [74]. US duplex Doppler fetal UA is essential for antepartum surveillance of complicated MC twins.

Multiple Gestations. US Cervix Transvaginal US cervix transvaginal evaluation for antepartum surveillance for all multiple gestations is useful for assessing cervical length, vasa, and placenta previa. Any cervical pathology, such as myoma or other masses, that may preclude vaginal delivery should also be assessed. Usually, a transabdominal examination is performed first, followed by transvaginal imaging if the initial evaluation is inadequate. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor. However, more recent literature has questioned the significance and usefulness of this practice, recommending against cervical length measurement after 26 weeks. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43]. If placenta previa or low-lying placenta has been suggested previously, assessment of the location of placental edge can be performed. US Duplex Doppler Fetal Middle Cerebral Artery For DC twins and multichorionic multiples, if there is a risk for fetal anemia or fetal hydrops is noted during surveillance, fetal MCA Doppler can be performed and interpreted using established nomograms. US duplex Multiple Gestations Doppler fetal MCA can be useful for surveillance of complicated DC or multichorionic gestations when there is concern for fetal anemia. Prognostic importance of MCA-PSV for outcome after laser ablation for TTTS has been reported. In a study by Trieu et al [74], there was no correlation between the incidence of elevated MCA-PSV before laser and fetal survival up to 7 days after laser. In contrast, the presence of an MCA-PSV above 1.5 MoM in the former donor twin 48 hours following laser was associated with higher risk for intrauterine fetal demise of the former donor within a week after surgery [74]. US duplex Doppler fetal UA is essential for antepartum surveillance of complicated MC twins.

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Multiple Gestations

This information is critical for detecting and staging TTTS and for evaluating fetuses diagnosed with sFGR. Doppler studies may show absence or reversal of EDF in the UA of the donor, information that is used in staging TTTS [70]. US Echocardiography Fetal Echocardiography can be performed for surveillance of DC or multichorionic gestations when cardiac defects or secondary cardiac decompensation is expected or observed. Multiple Gestations for fetal intervention. Fetoscopic laser ablation of placental vascular anastomoses can help reverse cardiac dysfunction, even in the most severe cases of TTTS [80]. Finneran et al [80] showed that laser treatment for TTTS causes rapid improvement in the cardiac function of recipient fetuses and that preoperative recipient myocardial performance index does not correlate with survival of either twin postoperatively. Hence, monitoring of cardiac function should be continued even after fetal intervention has been performed [80-82]. US Pregnant Uterus Biophysical Profile BPP can be performed in late second and third trimesters for assessing fetal well-being for all multiple pregnancies. US Pregnant Uterus Transabdominal Transabdominal US of the pregnant uterus continues to be the mainstay for surveillance imaging of complicated multiple gestations. Complicated multiple gestations require sonographic surveillance at frequent intervals varying between 2 to 3 days to 2 to 3 weeks based on the abnormality and fetal status [9]. Higher-risk gestations merit frequent surveillance. Due to variability and SDs in measurements, growth and biometry is usually performed no more frequently than every 2 weeks [9]. The discordance in estimated fetal weights should be calculated and documented at each scan in which growth and fetal weight estimates are performed. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed.

Multiple Gestations. This information is critical for detecting and staging TTTS and for evaluating fetuses diagnosed with sFGR. Doppler studies may show absence or reversal of EDF in the UA of the donor, information that is used in staging TTTS [70]. US Echocardiography Fetal Echocardiography can be performed for surveillance of DC or multichorionic gestations when cardiac defects or secondary cardiac decompensation is expected or observed. Multiple Gestations for fetal intervention. Fetoscopic laser ablation of placental vascular anastomoses can help reverse cardiac dysfunction, even in the most severe cases of TTTS [80]. Finneran et al [80] showed that laser treatment for TTTS causes rapid improvement in the cardiac function of recipient fetuses and that preoperative recipient myocardial performance index does not correlate with survival of either twin postoperatively. Hence, monitoring of cardiac function should be continued even after fetal intervention has been performed [80-82]. US Pregnant Uterus Biophysical Profile BPP can be performed in late second and third trimesters for assessing fetal well-being for all multiple pregnancies. US Pregnant Uterus Transabdominal Transabdominal US of the pregnant uterus continues to be the mainstay for surveillance imaging of complicated multiple gestations. Complicated multiple gestations require sonographic surveillance at frequent intervals varying between 2 to 3 days to 2 to 3 weeks based on the abnormality and fetal status [9]. Higher-risk gestations merit frequent surveillance. Due to variability and SDs in measurements, growth and biometry is usually performed no more frequently than every 2 weeks [9]. The discordance in estimated fetal weights should be calculated and documented at each scan in which growth and fetal weight estimates are performed. If prior history of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed.

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acrac_3102391_0

Abdominal Aortic Aneurysm Follow up Without Repair

Introduction/Background Abdominal aortic aneurysm (AAA) is defined as an aneurysmal dilation of the abdominal aorta of at least 3 cm in diameter. This entity has a high degree of morbidity and mortality in the event of rupture [1,2]. To mitigate this risk, screening programs have been widely instituted to identify small, developing aneurysms. Such screening reduces morbidity and health care costs related to this disease [3-8]. An increasing number of aneurysms are identified incidentally on ultrasound (US) and cross-sectional imaging, creating a growing cohort of patients with known AAA [9-12]. The reported prevalence of AAA in persons >65 years of age ranges from 1.7% to 4.5% for men and 0.5% to 1.3% for women [11,13,14]. Special Imaging Considerations For the purposes of distinguishing between CT and CT angiography (CTA), ACR Appropriateness Criteria topics use the definition in the Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [25]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and recons/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. aResearch Author, UT Southwestern Medical Center, Dallas, Texas. bUT Southwestern Medical Center, Dallas, Texas. cPanel Chair, UT Southwestern Medical Center, Dallas, Texas. dPanel Vice-chair, University of Michigan Health System, Ann Arbor, Michigan. eMayo Clinic, Rochester, Minnesota. fTufts University School of Medicine, Boston, Massachusetts; Society for Vascular Surgery. gUniversity of Wisconsin, Madison, Wisconsin. hMassachusetts General Hospital, Boston, Massachusetts. iUniversity of Alabama at Birmingham, Birmingham, Alabama. jMayo Clinic, Rochester, Minnesota. kUniversity of Michigan Health System, Ann Arbor, Michigan.

Abdominal Aortic Aneurysm Follow up Without Repair . Introduction/Background Abdominal aortic aneurysm (AAA) is defined as an aneurysmal dilation of the abdominal aorta of at least 3 cm in diameter. This entity has a high degree of morbidity and mortality in the event of rupture [1,2]. To mitigate this risk, screening programs have been widely instituted to identify small, developing aneurysms. Such screening reduces morbidity and health care costs related to this disease [3-8]. An increasing number of aneurysms are identified incidentally on ultrasound (US) and cross-sectional imaging, creating a growing cohort of patients with known AAA [9-12]. The reported prevalence of AAA in persons >65 years of age ranges from 1.7% to 4.5% for men and 0.5% to 1.3% for women [11,13,14]. Special Imaging Considerations For the purposes of distinguishing between CT and CT angiography (CTA), ACR Appropriateness Criteria topics use the definition in the Practice Parameter for the Performance and Interpretation of Body Computed Tomography Angiography (CTA) [25]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and recons/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. aResearch Author, UT Southwestern Medical Center, Dallas, Texas. bUT Southwestern Medical Center, Dallas, Texas. cPanel Chair, UT Southwestern Medical Center, Dallas, Texas. dPanel Vice-chair, University of Michigan Health System, Ann Arbor, Michigan. eMayo Clinic, Rochester, Minnesota. fTufts University School of Medicine, Boston, Massachusetts; Society for Vascular Surgery. gUniversity of Wisconsin, Madison, Wisconsin. hMassachusetts General Hospital, Boston, Massachusetts. iUniversity of Alabama at Birmingham, Birmingham, Alabama. jMayo Clinic, Rochester, Minnesota. kUniversity of Michigan Health System, Ann Arbor, Michigan.

3102391

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Abdominal Aortic Aneurysm Follow up Without Repair

lLoyola University Medical Center, Maywood, Illinois. mColumbia University Medical Center, New York, New York. nUT Southwestern Medical Center, Dallas, Texas. oSpecialty Chair, UMass Memorial Medical Center, Worcester, Massachusetts. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] AAA Follow-up (Without Repair) Discussion of Procedures by Variant Variant 1: Asymptomatic abdominal aortic aneurysm surveillance (without repair). US Duplex Doppler Aorta Abdomen US is the most widely studied and utilized imaging tool for evaluating an AAA, both for screening and during surveillance. US has been verified as having consistent measurement accuracy, which can approximate the accuracy demonstrated by CT and MRI or MR angiography (MRA) [17,18,26,27]. Studies have reported that US may underestimate the maximum AAA diameter by 4 mm, on average, and the interobserver measurement difference can range from 2 to 10 mm with US compared with <2 mm using CT [27-31]. Evidence is still lacking as to whether these differences are clinically impactful. Variation in accuracy is believed to be related to measurement technique. For example, there is debate as to whether to place the measurement caliper on the outer or inner edge of the vessel, without clear consensus on an ideal methodology [31]. Finally, no significant difference between rate of growth measurements between US and CT has been found [18,32]. US is also less capable of identifying specific aneurysm features beyond diameter, such as intraluminal thrombus or adjacent inflammation, both of which are more easily identified on CT [21,33,34].

Abdominal Aortic Aneurysm Follow up Without Repair . lLoyola University Medical Center, Maywood, Illinois. mColumbia University Medical Center, New York, New York. nUT Southwestern Medical Center, Dallas, Texas. oSpecialty Chair, UMass Memorial Medical Center, Worcester, Massachusetts. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] AAA Follow-up (Without Repair) Discussion of Procedures by Variant Variant 1: Asymptomatic abdominal aortic aneurysm surveillance (without repair). US Duplex Doppler Aorta Abdomen US is the most widely studied and utilized imaging tool for evaluating an AAA, both for screening and during surveillance. US has been verified as having consistent measurement accuracy, which can approximate the accuracy demonstrated by CT and MRI or MR angiography (MRA) [17,18,26,27]. Studies have reported that US may underestimate the maximum AAA diameter by 4 mm, on average, and the interobserver measurement difference can range from 2 to 10 mm with US compared with <2 mm using CT [27-31]. Evidence is still lacking as to whether these differences are clinically impactful. Variation in accuracy is believed to be related to measurement technique. For example, there is debate as to whether to place the measurement caliper on the outer or inner edge of the vessel, without clear consensus on an ideal methodology [31]. Finally, no significant difference between rate of growth measurements between US and CT has been found [18,32]. US is also less capable of identifying specific aneurysm features beyond diameter, such as intraluminal thrombus or adjacent inflammation, both of which are more easily identified on CT [21,33,34].

3102391

acrac_3102391_2

Abdominal Aortic Aneurysm Follow up Without Repair

CTA Abdomen and Pelvis CTA of the abdomen and pelvis presents many benefits over the other modalities. Relative to US, CTA is considered slightly more accurate at determining aneurysm diameter [27,30,31]. The use of iodinated contrast carries its own risks and contraindications that require consideration [35]. CT Abdomen and Pelvis The majority of evidence regarding AAA surveillance using CT is based on CTA data and is primarily related to contrast bolus timing. Contrast-enhanced CT is well established in the literature and is capable of identifying aortic aneurysms, with many papers discussing incidental AAA identification [9,11,13]. There is no specific literature regarding the use of noncontrast CT in the surveillance of AAA. One study reviewed the incidence of AAA incidentally found during CT colonography. This included patients who underwent CT imaging, some with and others without the use of intravenous (IV) contrast. This review did not distinguish the difference between those patients [11]. This technique could theoretically be of use in patients with chronic renal disease who have aneurysms less amenable to imaging by US. Noncontrast imaging can be employed in CTA protocols to evaluate for calcification, with spectral CT scanners offering virtual noncontrast reconstructions as an alternative. MRI Abdomen and Pelvis There is no relevant literature regarding the use of MRI for AAA surveillance in this setting; although, MRI may be useful in some cases. Similar to CT, there is excellent reproducibility in measurements between MRI examinations, a critical characteristic in monitoring for subtle changes in AAA size. Aortography Abdomen There is no relevant literature regarding the use of conventional angiography in the surveillance of AAA. Noninvasive techniques to monitor aneurysm characteristics make this invasive option less reasonable.

Abdominal Aortic Aneurysm Follow up Without Repair . CTA Abdomen and Pelvis CTA of the abdomen and pelvis presents many benefits over the other modalities. Relative to US, CTA is considered slightly more accurate at determining aneurysm diameter [27,30,31]. The use of iodinated contrast carries its own risks and contraindications that require consideration [35]. CT Abdomen and Pelvis The majority of evidence regarding AAA surveillance using CT is based on CTA data and is primarily related to contrast bolus timing. Contrast-enhanced CT is well established in the literature and is capable of identifying aortic aneurysms, with many papers discussing incidental AAA identification [9,11,13]. There is no specific literature regarding the use of noncontrast CT in the surveillance of AAA. One study reviewed the incidence of AAA incidentally found during CT colonography. This included patients who underwent CT imaging, some with and others without the use of intravenous (IV) contrast. This review did not distinguish the difference between those patients [11]. This technique could theoretically be of use in patients with chronic renal disease who have aneurysms less amenable to imaging by US. Noncontrast imaging can be employed in CTA protocols to evaluate for calcification, with spectral CT scanners offering virtual noncontrast reconstructions as an alternative. MRI Abdomen and Pelvis There is no relevant literature regarding the use of MRI for AAA surveillance in this setting; although, MRI may be useful in some cases. Similar to CT, there is excellent reproducibility in measurements between MRI examinations, a critical characteristic in monitoring for subtle changes in AAA size. Aortography Abdomen There is no relevant literature regarding the use of conventional angiography in the surveillance of AAA. Noninvasive techniques to monitor aneurysm characteristics make this invasive option less reasonable.

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acrac_69368_0

Lower Urinary Tract Symptoms Suspicion of Benign Prostatic Hyperplasia

Initial assessment of LUTS includes obtaining relevant medical history, performing a focused physical examination, and assessing symptom severity by one of several validated questionnaires. The International Prostate Symptom Score (IPSS) is used most commonly in the United States, and other validated questionnaires include the International Consultation on Incontinence Questionnaire and the Danish Prostate Symptom Score. These scores identify dominant symptoms (storage or voiding) and can be used to monitor response to therapy. Voiding charts (eg, frequency-volume chart) can be created by the patient to actively record several days of voiding time and volume. A physical examination should include an abdominal examination for bladder distention, a detailed genitourinary examination for any stricturing disease or urethral mass, a digital rectal examination to assess prostate size, and a neurological examination of the perineum and lower limbs. Digital rectal examination can be inaccurate for volume estimation and cancer detection and is most useful for identifying an enlarged prostate with volume >50g [4]. Initial laboratory analysis may include prostate serum antigen level if desired, following appropriate shared decision-making discussion. Urinalysis can be obtained to evaluate for urinary tract infection, glucosuria and proteinuria as cause of urinary frequency, and microhematuria. Urinalysis results may lead to an additional workup beyond the scope of this topic [1,2,5]. Pressure flow urodynamics is considered the reference standard for determining the underlying cause of LUTS and differentiating between storage and voiding abnormalities. Watchful waiting with lifestyle modifications is appropriate for patients without bothersome symptoms. For patients with moderate to severe symptoms, medical therapy with 1-adrenoceptor antagonists is a first-line therapy.

Lower Urinary Tract Symptoms Suspicion of Benign Prostatic Hyperplasia. Initial assessment of LUTS includes obtaining relevant medical history, performing a focused physical examination, and assessing symptom severity by one of several validated questionnaires. The International Prostate Symptom Score (IPSS) is used most commonly in the United States, and other validated questionnaires include the International Consultation on Incontinence Questionnaire and the Danish Prostate Symptom Score. These scores identify dominant symptoms (storage or voiding) and can be used to monitor response to therapy. Voiding charts (eg, frequency-volume chart) can be created by the patient to actively record several days of voiding time and volume. A physical examination should include an abdominal examination for bladder distention, a detailed genitourinary examination for any stricturing disease or urethral mass, a digital rectal examination to assess prostate size, and a neurological examination of the perineum and lower limbs. Digital rectal examination can be inaccurate for volume estimation and cancer detection and is most useful for identifying an enlarged prostate with volume >50g [4]. Initial laboratory analysis may include prostate serum antigen level if desired, following appropriate shared decision-making discussion. Urinalysis can be obtained to evaluate for urinary tract infection, glucosuria and proteinuria as cause of urinary frequency, and microhematuria. Urinalysis results may lead to an additional workup beyond the scope of this topic [1,2,5]. Pressure flow urodynamics is considered the reference standard for determining the underlying cause of LUTS and differentiating between storage and voiding abnormalities. Watchful waiting with lifestyle modifications is appropriate for patients without bothersome symptoms. For patients with moderate to severe symptoms, medical therapy with 1-adrenoceptor antagonists is a first-line therapy.

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acrac_69368_1

Lower Urinary Tract Symptoms Suspicion of Benign Prostatic Hyperplasia

The 5 -reductase inhibitors can be helpful for patients with prostate volume >40 mL [6]. The muscarinic receptor antagonists and phosphodiesterase type 5 inhibitors can be used for storage symptoms [6]. Transurethral resection of the prostate is the standard surgical treatment for prostate volume 30 to 80 mL, with surgery or transurethral holmium laser enucleation for prostate volume >80 mL [6]. Other interventional options include laser ablation, transurethral needle or microwave ablation, transurethral resection, and prostate artery embolization. Treatment decisions vary by prostate volume and patient comorbidities [6,7]. aMayo Clinic, Jacksonville, Florida. bPanel Chair, University of Chicago, Chicago, Illinois. cPanel Vice-Chair, Duke University Medical Center, Durham, North Carolina. dMemorial Sloan Kettering Cancer Center, New York, New York. eMcGill University, Montreal, Quebec, Canada. fMayo Clinic, Rochester, Minnesota. gUrology Clinics of North Texas, Dallas, Texas; American Urological Association. hUniversity of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; American Society of Nephrology. iUPMC, Pittsburgh, Pennsylvania; American Urological Association. jCleveland Clinic, Cleveland, Ohio. kStanford University Medical Center, Stanford, California. lOttawa Hospital Research Institute and the Department of Radiology, The University of Ottawa, Ottawa, Ontario, Canada. mEmory University Hospital, Atlanta, Georgia. nNational Institutes of Health, Bethesda, Maryland. oThe University of Texas MD Anderson Cancer Center, Houston, Texas. pUniversity of Washington, Seattle Cancer Care Alliance, Seattle, Washington. qSpecialty Chair, University of Alabama at Birmingham, Birmingham, Alabama. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels.

Lower Urinary Tract Symptoms Suspicion of Benign Prostatic Hyperplasia. The 5 -reductase inhibitors can be helpful for patients with prostate volume >40 mL [6]. The muscarinic receptor antagonists and phosphodiesterase type 5 inhibitors can be used for storage symptoms [6]. Transurethral resection of the prostate is the standard surgical treatment for prostate volume 30 to 80 mL, with surgery or transurethral holmium laser enucleation for prostate volume >80 mL [6]. Other interventional options include laser ablation, transurethral needle or microwave ablation, transurethral resection, and prostate artery embolization. Treatment decisions vary by prostate volume and patient comorbidities [6,7]. aMayo Clinic, Jacksonville, Florida. bPanel Chair, University of Chicago, Chicago, Illinois. cPanel Vice-Chair, Duke University Medical Center, Durham, North Carolina. dMemorial Sloan Kettering Cancer Center, New York, New York. eMcGill University, Montreal, Quebec, Canada. fMayo Clinic, Rochester, Minnesota. gUrology Clinics of North Texas, Dallas, Texas; American Urological Association. hUniversity of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; American Society of Nephrology. iUPMC, Pittsburgh, Pennsylvania; American Urological Association. jCleveland Clinic, Cleveland, Ohio. kStanford University Medical Center, Stanford, California. lOttawa Hospital Research Institute and the Department of Radiology, The University of Ottawa, Ottawa, Ontario, Canada. mEmory University Hospital, Atlanta, Georgia. nNational Institutes of Health, Bethesda, Maryland. oThe University of Texas MD Anderson Cancer Center, Houston, Texas. pUniversity of Washington, Seattle Cancer Care Alliance, Seattle, Washington. qSpecialty Chair, University of Alabama at Birmingham, Birmingham, Alabama. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels.

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acrac_69368_2

Lower Urinary Tract Symptoms Suspicion of Benign Prostatic Hyperplasia

Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] Lower Urinary Tract Symptoms-Suspicion of BPH Discussion of Procedures by Variant Variant 1: Lower urinary tract symptoms. Suspicion of benign prostatic hyperplasia. Initial imaging. Radiography Abdomen Radiographs do not directly image the prostate and are of low diagnostic yield in patients with LUTS [8]. A distended bladder may be visible on radiographs as a pelvic mass; however, the timing of last void is usually unavailable, making this appearance a finding of uncertain significance. Bladder stones can be identified on radiographs. Radiography Intravenous Urography Intravenous urography is now rarely performed as it has been replaced by CT urography at most centers [9]. Positive yield of intravenous urography for BOO is <15% [10,11]. In patients with stones, hematuria, or atypical history, CT urography may be considered for further evaluation [12]. Fluoroscopy Retrograde Urethrography Retrograde urethrography does not directly image the prostate or provide adequate evaluation of prostate size. It may be useful if urethral stricture is considered as a cause of urinary obstruction. Fluoroscopy Voiding Cystourethrography Voiding cystourethrography does not directly image the prostate or provide adequate evaluation of prostate size. It may be useful if urethral stricture is considered as a cause of urinary obstruction. TRUS Prostate Grayscale transrectal ultrasound (TRUS) is the most commonly used modality to image the prostate. Although more invasive, TRUS measurement of prostate volume is more accurate than digital rectal examination or pelvic US [13,14], though correlation between TRUS and pelvic US is consistent when bladder volumes are <400 mL [15].

Lower Urinary Tract Symptoms Suspicion of Benign Prostatic Hyperplasia. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] Lower Urinary Tract Symptoms-Suspicion of BPH Discussion of Procedures by Variant Variant 1: Lower urinary tract symptoms. Suspicion of benign prostatic hyperplasia. Initial imaging. Radiography Abdomen Radiographs do not directly image the prostate and are of low diagnostic yield in patients with LUTS [8]. A distended bladder may be visible on radiographs as a pelvic mass; however, the timing of last void is usually unavailable, making this appearance a finding of uncertain significance. Bladder stones can be identified on radiographs. Radiography Intravenous Urography Intravenous urography is now rarely performed as it has been replaced by CT urography at most centers [9]. Positive yield of intravenous urography for BOO is <15% [10,11]. In patients with stones, hematuria, or atypical history, CT urography may be considered for further evaluation [12]. Fluoroscopy Retrograde Urethrography Retrograde urethrography does not directly image the prostate or provide adequate evaluation of prostate size. It may be useful if urethral stricture is considered as a cause of urinary obstruction. Fluoroscopy Voiding Cystourethrography Voiding cystourethrography does not directly image the prostate or provide adequate evaluation of prostate size. It may be useful if urethral stricture is considered as a cause of urinary obstruction. TRUS Prostate Grayscale transrectal ultrasound (TRUS) is the most commonly used modality to image the prostate. Although more invasive, TRUS measurement of prostate volume is more accurate than digital rectal examination or pelvic US [13,14], though correlation between TRUS and pelvic US is consistent when bladder volumes are <400 mL [15].

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Lower Urinary Tract Symptoms Suspicion of Benign Prostatic Hyperplasia

Prostate volume has low correlation with initial symptoms [16] but may predict symptom progression and response to 5 -reductase inhibitors, as well as guide surgical procedures [6]. The addition of spectral Doppler assessment is not helpful to differentiate benign from malignant areas [17], and further study of prostate arterial resistive index measurement is needed to determine clinical usefulness [18]. US Pelvis US is the preferred method to assess bladder volume and postvoid residual over catheterization and can be performed with a specific bladder scan unit or pelvic US. A measurable postvoid residual can be seen with both BOO and decreased detrusor function. Although no current postvoid residual threshold value can diagnose BOO or guide treatment [1,2], a persistent postvoid residual >100 mL or increasing postvoid residual over time may predict acute urinary retention, poor response to medical treatment, and deterioration of symptoms [1,19]. US measurement of bladder wall thickness includes the entire width of the bladder wall, whereas detrusor wall thickness measures the hypoechoic muscle between the more echogenic mucosa and adventitia. A study of 157 patients, of which 48 had BOO by urodynamics, identified optimal cutoff of 3.7-mm wall thickness for identifying patients with BOO by receiver operator curve analysis [25]. Although detrusor wall thickening has been shown to increase in BOO, the ratio of bladder to detrusor thickness depends on degree of bladder filling [28]. US-estimated bladder weight can be calculated from bladder volume and wall thickness, assuming a spherical shape. This value may also correlate with BOO and acute urinary retention [29,30]. Lower Urinary Tract Symptoms-Suspicion of BPH US Kidneys Retroperitoneal Routine imaging of the upper urinary tract with renal US is not usually indicated in uncomplicated LUTS [1,2,31].

Lower Urinary Tract Symptoms Suspicion of Benign Prostatic Hyperplasia. Prostate volume has low correlation with initial symptoms [16] but may predict symptom progression and response to 5 -reductase inhibitors, as well as guide surgical procedures [6]. The addition of spectral Doppler assessment is not helpful to differentiate benign from malignant areas [17], and further study of prostate arterial resistive index measurement is needed to determine clinical usefulness [18]. US Pelvis US is the preferred method to assess bladder volume and postvoid residual over catheterization and can be performed with a specific bladder scan unit or pelvic US. A measurable postvoid residual can be seen with both BOO and decreased detrusor function. Although no current postvoid residual threshold value can diagnose BOO or guide treatment [1,2], a persistent postvoid residual >100 mL or increasing postvoid residual over time may predict acute urinary retention, poor response to medical treatment, and deterioration of symptoms [1,19]. US measurement of bladder wall thickness includes the entire width of the bladder wall, whereas detrusor wall thickness measures the hypoechoic muscle between the more echogenic mucosa and adventitia. A study of 157 patients, of which 48 had BOO by urodynamics, identified optimal cutoff of 3.7-mm wall thickness for identifying patients with BOO by receiver operator curve analysis [25]. Although detrusor wall thickening has been shown to increase in BOO, the ratio of bladder to detrusor thickness depends on degree of bladder filling [28]. US-estimated bladder weight can be calculated from bladder volume and wall thickness, assuming a spherical shape. This value may also correlate with BOO and acute urinary retention [29,30]. Lower Urinary Tract Symptoms-Suspicion of BPH US Kidneys Retroperitoneal Routine imaging of the upper urinary tract with renal US is not usually indicated in uncomplicated LUTS [1,2,31].

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acrac_69356_0

Left Lower Quadrant Pain

Introduction/Background The differential diagnosis for left lower quadrant pain includes gastrointestinal, gynecologic, urologic, and body wall pathology. These conditions range from the benign and self-limited to life-threatening surgical emergencies. Along with patient history, physical examination, and laboratory tests, imaging is often critical to limit the differential diagnosis and identify life-threatening abnormalities [1]. Appropriate imaging triage for patients with left lower quadrant pain should address the diagnostic possibilities and consider which imaging modality can best add clinically relevant information to help guide management. In older patients, early diagnosis is important because this population has a higher rate of comorbid disease-related complications [2-6]. Furthermore, symptoms and clinical findings may be nonspecific in this population, with atypical presentation of common diseases. Acute colonic diverticulitis is the most common explanation for left lower quadrant pain, and the prevalence is rising. There was a 50% increase in diverticulitis events between 2000 and 2007 [6,7]. Colonic diverticulitis, which results from inflammation of colonic diverticula, is common in Western populations, likely due to inadequate dietary fiber. Approximately 10% of the Western population has diverticulosis at 40 years of age; this increases to 70% or more in older patients. It has been estimated that between 5% and 25% of patients with diverticulosis will develop diverticulitis [3,8]. Although the most common cause of adult left lower quadrant pain is acute diverticulitis of the sigmoid or descending colon, other common causes of left lower quadrant pain include colitis, inflammatory bowel disease, epiploic appendagitis, bowel obstruction, hernia, ovarian and fallopian tube pathology, pyelonephritis, and urolithiasis [6,9]. Many of these conditions can present with symptoms that overlap with the acute presentation of diverticulitis.

Left Lower Quadrant Pain. Introduction/Background The differential diagnosis for left lower quadrant pain includes gastrointestinal, gynecologic, urologic, and body wall pathology. These conditions range from the benign and self-limited to life-threatening surgical emergencies. Along with patient history, physical examination, and laboratory tests, imaging is often critical to limit the differential diagnosis and identify life-threatening abnormalities [1]. Appropriate imaging triage for patients with left lower quadrant pain should address the diagnostic possibilities and consider which imaging modality can best add clinically relevant information to help guide management. In older patients, early diagnosis is important because this population has a higher rate of comorbid disease-related complications [2-6]. Furthermore, symptoms and clinical findings may be nonspecific in this population, with atypical presentation of common diseases. Acute colonic diverticulitis is the most common explanation for left lower quadrant pain, and the prevalence is rising. There was a 50% increase in diverticulitis events between 2000 and 2007 [6,7]. Colonic diverticulitis, which results from inflammation of colonic diverticula, is common in Western populations, likely due to inadequate dietary fiber. Approximately 10% of the Western population has diverticulosis at 40 years of age; this increases to 70% or more in older patients. It has been estimated that between 5% and 25% of patients with diverticulosis will develop diverticulitis [3,8]. Although the most common cause of adult left lower quadrant pain is acute diverticulitis of the sigmoid or descending colon, other common causes of left lower quadrant pain include colitis, inflammatory bowel disease, epiploic appendagitis, bowel obstruction, hernia, ovarian and fallopian tube pathology, pyelonephritis, and urolithiasis [6,9]. Many of these conditions can present with symptoms that overlap with the acute presentation of diverticulitis.

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Left Lower Quadrant Pain

Special Imaging Considerations Diverticulitis and Colon Cancer: Perforated colon cancer can mimic diverticulitis [10]. CT findings that suggest colon cancer rather than diverticulitis include abnormal pericolic lymph nodes (>1 cm in short axis and/or rounded) or a luminal mass [10-12]. Patients with uncomplicated diverticulitis do not have a higher risk of colon cancer than the general population [10]. The prevalence of colon cancer in patients with uncomplicated diverticulitis has been reported to be 0.5% to 0.9% [10,13,14]. Colonoscopy after a diagnosis of uncomplicated diverticulitis is not indicated in the general population. [10,15]. Colonoscopy may have a role in the following situations: 1) patients for whom colonoscopy is indicated for colon cancer screening but in whom it has not yet been performed, 2) patients with abnormal pericolic lymph node(s), 3) patients with a luminal colon mass, and 4) patients with an uncertain diagnosis (eg, inflammatory bowel disease or ischemic colitis) [16]. Colonoscopy in general should be avoided in aUniversity of California San Francisco, San Francisco, California. bPanel Chair, University of Wisconsin Hospital & Clinics, Madison, Wisconsin. cPanel Vice-Chair, University of California San Diego, San Diego, California. dPenn State Milton S. Hershey Medical Center, Hershey, Pennsylvania. eUniversity of Texas Health Science Center at Houston and McGovern Medical School, Houston, Texas; American Gastroenterological Association. fMedstar Georgetown University Hospital, Washington, District of Columbia, Primary care physician. gNYU Grossman School of Medicine, New York, New York. hMemorial Sloan Kettering Cancer Center, New York, New York. iMassachusetts General Hospital, Boston, Massachusetts. jOregon Health and Science University, Portland, Oregon. kCleveland Clinic, Cleveland, Ohio. lSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians.

Left Lower Quadrant Pain. Special Imaging Considerations Diverticulitis and Colon Cancer: Perforated colon cancer can mimic diverticulitis [10]. CT findings that suggest colon cancer rather than diverticulitis include abnormal pericolic lymph nodes (>1 cm in short axis and/or rounded) or a luminal mass [10-12]. Patients with uncomplicated diverticulitis do not have a higher risk of colon cancer than the general population [10]. The prevalence of colon cancer in patients with uncomplicated diverticulitis has been reported to be 0.5% to 0.9% [10,13,14]. Colonoscopy after a diagnosis of uncomplicated diverticulitis is not indicated in the general population. [10,15]. Colonoscopy may have a role in the following situations: 1) patients for whom colonoscopy is indicated for colon cancer screening but in whom it has not yet been performed, 2) patients with abnormal pericolic lymph node(s), 3) patients with a luminal colon mass, and 4) patients with an uncertain diagnosis (eg, inflammatory bowel disease or ischemic colitis) [16]. Colonoscopy in general should be avoided in aUniversity of California San Francisco, San Francisco, California. bPanel Chair, University of Wisconsin Hospital & Clinics, Madison, Wisconsin. cPanel Vice-Chair, University of California San Diego, San Diego, California. dPenn State Milton S. Hershey Medical Center, Hershey, Pennsylvania. eUniversity of Texas Health Science Center at Houston and McGovern Medical School, Houston, Texas; American Gastroenterological Association. fMedstar Georgetown University Hospital, Washington, District of Columbia, Primary care physician. gNYU Grossman School of Medicine, New York, New York. hMemorial Sloan Kettering Cancer Center, New York, New York. iMassachusetts General Hospital, Boston, Massachusetts. jOregon Health and Science University, Portland, Oregon. kCleveland Clinic, Cleveland, Ohio. lSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians.

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Left Lower Quadrant Pain

mDuke Signature Care, Durham, North Carolina; American College of Physicians. nMallinckrodt Institute of Radiology, Saint Louis, Missouri; Committee on Emergency Radiology-GSER. oUniversity of North Carolina at Chapel Hill, Chapel Hill, North Carolina. pUniversity of California San Diego, San Diego, California. qMcMaster University, Hamilton, Ontario, Canada; Commission on Nuclear Medicine and Molecular Imaging. rSpecialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Left Lower Quadrant Pain the setting of acute diverticulitis because of the risk of perforation; if indicated, it usually is deferred until the acute event has resolved. Use of Oral and Rectal Contrast Media for CT: Neither oral nor rectal contrast is required for the routine evaluation of left lower quadrant pain. More than 20 studies have found no benefit for oral contrast in the evaluation of abdominal pain in the emergency department [17]. Rectal contrast may have a limited role in evaluating for perforation after surgical intervention. OR Discussion of Procedures by Variant Variant 1: Left lower quadrant pain. Initial imaging. This variant applies if there is nonspecific pain in the left lower quadrant with a broad differential diagnosis including gastrointestinal, gynecologic, urologic, and body wall pathology. If diverticulitis is primarily suspected, please refer to Variant 2 (suspected diverticulitis) or Variant 3 (suspected complication of diverticulitis). CT Abdomen and Pelvis CT is the most useful examination for left lower quadrant pain [16,19].

Left Lower Quadrant Pain. mDuke Signature Care, Durham, North Carolina; American College of Physicians. nMallinckrodt Institute of Radiology, Saint Louis, Missouri; Committee on Emergency Radiology-GSER. oUniversity of North Carolina at Chapel Hill, Chapel Hill, North Carolina. pUniversity of California San Diego, San Diego, California. qMcMaster University, Hamilton, Ontario, Canada; Commission on Nuclear Medicine and Molecular Imaging. rSpecialty Chair, Virginia Commonwealth University Medical Center, Richmond, Virginia. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: [email protected] Left Lower Quadrant Pain the setting of acute diverticulitis because of the risk of perforation; if indicated, it usually is deferred until the acute event has resolved. Use of Oral and Rectal Contrast Media for CT: Neither oral nor rectal contrast is required for the routine evaluation of left lower quadrant pain. More than 20 studies have found no benefit for oral contrast in the evaluation of abdominal pain in the emergency department [17]. Rectal contrast may have a limited role in evaluating for perforation after surgical intervention. OR Discussion of Procedures by Variant Variant 1: Left lower quadrant pain. Initial imaging. This variant applies if there is nonspecific pain in the left lower quadrant with a broad differential diagnosis including gastrointestinal, gynecologic, urologic, and body wall pathology. If diverticulitis is primarily suspected, please refer to Variant 2 (suspected diverticulitis) or Variant 3 (suspected complication of diverticulitis). CT Abdomen and Pelvis CT is the most useful examination for left lower quadrant pain [16,19].

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Left Lower Quadrant Pain

It is accurate and guides appropriate management, regardless of patient sex or patient body habitus [20]. CT is sensitive for small quantities of extraluminal intraperitoneal or retroperitoneal air [21,22]. Extraluminal air can be a critical finding indicating luminal perforation and often has surgical implications. Colonic diverticulitis is a common cause of small-volume extraluminal air at CT. Large-volume extraperitoneal air is more commonly seen with peptic ulcer disease or anastomotic dehiscence but can indicate a large-caliber perforation from diverticulitis [21]. Mortality rates are higher in patients with larger amounts of extraluminal air [21]. Fluoroscopic Contrast-Enhanced Enema Contrast-enhanced enema is not generally useful as the initial imaging test in patients with left lower quadrant pain. Although it may hold some utility in sigmoid and small bowel pathology, contrast enema would be of little value in the work up of other potential etiologies of left lower quadrant pain including gynecologic or urologic conditions. No recent studies in the utility of fluoroscopic contrast-enhanced enema and left lower quadrant pain have been published. Left Lower Quadrant Pain MRI Abdomen and Pelvis MRI is not useful for the initial evaluation of acute abdominal pain [1,12]. It is less sensitive for extraluminal air and urinary tract calculi, is more time-consuming to perform, requires an active screening process for indwelling devices and metal, and is more subject to motion artifacts in symptomatic patients. Few have compared the diagnostic accuracy of CT and MRI for the evaluation of left lower quadrant pain. In a 2013 pilot study, 30 consecutive patients with either sigmoid colon cancer (n = 15) or recent treatment for acute diverticulitis (n = 15) were imaged with CT or unenhanced MRI (T2-weighted and diffusion-weighted imaging) [12].

Left Lower Quadrant Pain. It is accurate and guides appropriate management, regardless of patient sex or patient body habitus [20]. CT is sensitive for small quantities of extraluminal intraperitoneal or retroperitoneal air [21,22]. Extraluminal air can be a critical finding indicating luminal perforation and often has surgical implications. Colonic diverticulitis is a common cause of small-volume extraluminal air at CT. Large-volume extraperitoneal air is more commonly seen with peptic ulcer disease or anastomotic dehiscence but can indicate a large-caliber perforation from diverticulitis [21]. Mortality rates are higher in patients with larger amounts of extraluminal air [21]. Fluoroscopic Contrast-Enhanced Enema Contrast-enhanced enema is not generally useful as the initial imaging test in patients with left lower quadrant pain. Although it may hold some utility in sigmoid and small bowel pathology, contrast enema would be of little value in the work up of other potential etiologies of left lower quadrant pain including gynecologic or urologic conditions. No recent studies in the utility of fluoroscopic contrast-enhanced enema and left lower quadrant pain have been published. Left Lower Quadrant Pain MRI Abdomen and Pelvis MRI is not useful for the initial evaluation of acute abdominal pain [1,12]. It is less sensitive for extraluminal air and urinary tract calculi, is more time-consuming to perform, requires an active screening process for indwelling devices and metal, and is more subject to motion artifacts in symptomatic patients. Few have compared the diagnostic accuracy of CT and MRI for the evaluation of left lower quadrant pain. In a 2013 pilot study, 30 consecutive patients with either sigmoid colon cancer (n = 15) or recent treatment for acute diverticulitis (n = 15) were imaged with CT or unenhanced MRI (T2-weighted and diffusion-weighted imaging) [12].

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Left Lower Quadrant Pain

MRI was found to be more accurate than CT for the differentiation of cancer from diverticulitis (sensitivity: 100% versus 67%, specificity: 100% versus 93%) [12]. There are no large studies confirming the diagnostic accuracy of MRI for the general evaluation of patients with left lower quadrant pain. Radiography Abdomen and Pelvis Radiography is not useful as the initial imaging test for the general population of patients with left lower quadrant pain because CT is more accurate. Radiography can identify large volume extraluminal air, can diagnose ileus or bowel obstruction, or may diagnose urolithiasis. CT is more sensitive and specific for each of those entities. Radiography may play a role in the triage of severely ill patients with a surgical abdomen, but CT is used in most cases. Variant 2: Left lower quadrant pain. Suspected diverticulitis. Initial imaging. Diverticulitis is suspected in patients with left lower quadrant pain, fever, and leukocytosis. However, this triad is present in only approximately 25% of patients with diverticulitis [6,26]. Misdiagnosis based on clinical assessment alone has been reported to be between 34% and 68% [6,27,28]. CT Abdomen and Pelvis CT is the most useful examination for patients with suspected colonic diverticulitis because of its reproducibility, superior diagnostic accuracy (98%) [16,19], accuracy for alternative diagnoses with a similar presentation [9,16], risk-stratification of patients for operative versus nonoperative treatment [8,30-32], and inpatient versus outpatient triage [33,34]. CT diagnosis of uncomplicated acute diverticulitis in the emergency department can prevent unneeded hospital admission [3,5]. This is because most colonic diverticulitis is uncomplicated and can be managed with outpatient antibiotics [11]. Juszczyk et al [5] showed that early CT for acute diverticulitis can reduce hospital admission by more than 50% and shorten hospital length of stay.

Left Lower Quadrant Pain. MRI was found to be more accurate than CT for the differentiation of cancer from diverticulitis (sensitivity: 100% versus 67%, specificity: 100% versus 93%) [12]. There are no large studies confirming the diagnostic accuracy of MRI for the general evaluation of patients with left lower quadrant pain. Radiography Abdomen and Pelvis Radiography is not useful as the initial imaging test for the general population of patients with left lower quadrant pain because CT is more accurate. Radiography can identify large volume extraluminal air, can diagnose ileus or bowel obstruction, or may diagnose urolithiasis. CT is more sensitive and specific for each of those entities. Radiography may play a role in the triage of severely ill patients with a surgical abdomen, but CT is used in most cases. Variant 2: Left lower quadrant pain. Suspected diverticulitis. Initial imaging. Diverticulitis is suspected in patients with left lower quadrant pain, fever, and leukocytosis. However, this triad is present in only approximately 25% of patients with diverticulitis [6,26]. Misdiagnosis based on clinical assessment alone has been reported to be between 34% and 68% [6,27,28]. CT Abdomen and Pelvis CT is the most useful examination for patients with suspected colonic diverticulitis because of its reproducibility, superior diagnostic accuracy (98%) [16,19], accuracy for alternative diagnoses with a similar presentation [9,16], risk-stratification of patients for operative versus nonoperative treatment [8,30-32], and inpatient versus outpatient triage [33,34]. CT diagnosis of uncomplicated acute diverticulitis in the emergency department can prevent unneeded hospital admission [3,5]. This is because most colonic diverticulitis is uncomplicated and can be managed with outpatient antibiotics [11]. Juszczyk et al [5] showed that early CT for acute diverticulitis can reduce hospital admission by more than 50% and shorten hospital length of stay.

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Left Lower Quadrant Pain

IV contrast material is commonly used to improve the characterization and detection of subtle bowel wall abnormalities and complications of diverticulitis (eg, abscess) [2,29]. However, for most patients, IV or intracavitary contrast material is not necessary for the diagnosis of diverticulitis [35,36]. Left Lower Quadrant Pain CT may also help predict which patients are likely to experience recurrent diverticulitis and thereby augment triage between surveillance and operative management [39]. Colonic wall thickness at the site of diverticulitis and extent of diverticulitis-related complication may predict recurrent diverticulitis. Dickerson et al [39] showed that patients with colonic wall thicknesses <9 mm had a 19% recurrence risk at 1 year compared with a 40% recurrence if the wall thickness was >15 mm. Numerous CT classification systems for diverticulitis have been proposed but none are widely integrated into clinical practice. For example, the Hinchey classification uses CT findings to differentiate between uncomplicated and complicated disease [29,40,41]. Endoscopic classification systems for predicting occurrence, recurrence, and need for surgery are undergoing validation. In patients requiring colonoscopy for colon cancer screening, CT colonography has been proposed as an alternative to colonoscopy [16,42]. Fluoroscopic Contrast-Enhanced Enema Contrast-enhanced enema is not useful as the initial imaging test in patients with suspected diverticulitis because CT is more accurate and easier to obtain [16]. Because diverticulitis is mainly an extramucosal process, and contrast enema shows only the secondary effects of inflammation on the colon, the evaluation of extraluminal abnormalities, such as abscesses and pericolonic fat inflammation, is limited. Contrast-enhanced enema can be used to assess for complications of diverticulitis (eg, fistula) and for presurgical planning before colonic resection (ie, assess length of stricture and colonic motility) [16].

Left Lower Quadrant Pain. IV contrast material is commonly used to improve the characterization and detection of subtle bowel wall abnormalities and complications of diverticulitis (eg, abscess) [2,29]. However, for most patients, IV or intracavitary contrast material is not necessary for the diagnosis of diverticulitis [35,36]. Left Lower Quadrant Pain CT may also help predict which patients are likely to experience recurrent diverticulitis and thereby augment triage between surveillance and operative management [39]. Colonic wall thickness at the site of diverticulitis and extent of diverticulitis-related complication may predict recurrent diverticulitis. Dickerson et al [39] showed that patients with colonic wall thicknesses <9 mm had a 19% recurrence risk at 1 year compared with a 40% recurrence if the wall thickness was >15 mm. Numerous CT classification systems for diverticulitis have been proposed but none are widely integrated into clinical practice. For example, the Hinchey classification uses CT findings to differentiate between uncomplicated and complicated disease [29,40,41]. Endoscopic classification systems for predicting occurrence, recurrence, and need for surgery are undergoing validation. In patients requiring colonoscopy for colon cancer screening, CT colonography has been proposed as an alternative to colonoscopy [16,42]. Fluoroscopic Contrast-Enhanced Enema Contrast-enhanced enema is not useful as the initial imaging test in patients with suspected diverticulitis because CT is more accurate and easier to obtain [16]. Because diverticulitis is mainly an extramucosal process, and contrast enema shows only the secondary effects of inflammation on the colon, the evaluation of extraluminal abnormalities, such as abscesses and pericolonic fat inflammation, is limited. Contrast-enhanced enema can be used to assess for complications of diverticulitis (eg, fistula) and for presurgical planning before colonic resection (ie, assess length of stricture and colonic motility) [16].

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Left Lower Quadrant Pain

MRI Abdomen and Pelvis In 2021, Jerjen et al [43] published a systematic review of the use of MRI for the diagnosis of acute colonic diverticulitis. The authors found that the diagnostic accuracy of MRI for diverticulitis is likely less than that of CT but insufficiently studied. Published estimates of diagnostic accuracy have been limited by study-related biases and small sample sizes. At present, there are insufficient published data to support the routine use of MRI for the diagnosis of suspected diverticulitis. Findings of diverticulitis at MRI are like those at CT: colonic diverticula, thickened diverticulum(la), and inflammation in the pericolic fat, with or without complication (eg, abscess, fistula, perforation). MRI is less sensitive than CT for small-volume extraluminal gas and is more affected by patient motion than CT. Abbreviated MR protocols are being explored to reduce acquisition time and enable emergency department evaluation for suspected diverticulitis, but this remains a research application. Radiography Abdomen and Pelvis Radiography is not useful as the initial imaging test for the general population of patients with suspected diverticulitis because CT is more accurate. Radiography can identify large volume extraluminal air or bowel obstruction. CT is more sensitive and specific for both. Radiography may play a role in the triage of severely ill patients with a surgical abdomen, but CT is used in most cases. US Abdomen Transabdominal Although US is the initial imaging test for suspected diverticulitis in some European countries and the developing world, it still is not widely used in the United States, possibly in part due to a larger obese population. Acute diverticulitis is diagnoseable by US using the following criteria [25]: 1. Short-segment colonic wall thickening (>5 mm) 2. Inflamed diverticulum in the thickened area (hypoechoic and surrounded by hyperechoic fat) 3. Noncompressible hyperechoic pericolic tissue

Left Lower Quadrant Pain. MRI Abdomen and Pelvis In 2021, Jerjen et al [43] published a systematic review of the use of MRI for the diagnosis of acute colonic diverticulitis. The authors found that the diagnostic accuracy of MRI for diverticulitis is likely less than that of CT but insufficiently studied. Published estimates of diagnostic accuracy have been limited by study-related biases and small sample sizes. At present, there are insufficient published data to support the routine use of MRI for the diagnosis of suspected diverticulitis. Findings of diverticulitis at MRI are like those at CT: colonic diverticula, thickened diverticulum(la), and inflammation in the pericolic fat, with or without complication (eg, abscess, fistula, perforation). MRI is less sensitive than CT for small-volume extraluminal gas and is more affected by patient motion than CT. Abbreviated MR protocols are being explored to reduce acquisition time and enable emergency department evaluation for suspected diverticulitis, but this remains a research application. Radiography Abdomen and Pelvis Radiography is not useful as the initial imaging test for the general population of patients with suspected diverticulitis because CT is more accurate. Radiography can identify large volume extraluminal air or bowel obstruction. CT is more sensitive and specific for both. Radiography may play a role in the triage of severely ill patients with a surgical abdomen, but CT is used in most cases. US Abdomen Transabdominal Although US is the initial imaging test for suspected diverticulitis in some European countries and the developing world, it still is not widely used in the United States, possibly in part due to a larger obese population. Acute diverticulitis is diagnoseable by US using the following criteria [25]: 1. Short-segment colonic wall thickening (>5 mm) 2. Inflamed diverticulum in the thickened area (hypoechoic and surrounded by hyperechoic fat) 3. Noncompressible hyperechoic pericolic tissue

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Left Lower Quadrant Pain

Meta-analyses and prospective studies have demonstrated sensitivity and positive predictive value of graded compression US for diverticulitis of >90%. The accuracy is modestly less than that of CT, but especially so in obese patients and in patients with distal sigmoid diverticulitis. US likely has lower specificity than CT and is less likely to identify an alternative diagnosis. Furthermore, US requires a higher level of training for the diagnosis of diverticulitis than does CT. Dirks et al [25] estimate that a minimum of 500 examinations is required for competency. If used as the initial imaging test at the bedside (eg, point of care), US may hypothetically reduce the number of CT scans performed without a negative effect on patient care, with CT used in inconclusive cases or when the US is negative. US also has the benefit of being noninvasive. Variant 3: Left lower quadrant pain. Suspected complication(s) of diverticulitis. Initial imaging. CT Abdomen and Pelvis CT is the most useful examination for patients with suspected complications of colonic diverticulitis because of its reproducibility, superior diagnostic accuracy [16,19], accuracy for alternative diagnoses with a similar presentation [9,16], risk-stratification of patients for operative versus nonoperative treatment [8,30-32], and inpatient versus outpatient triage [33,34]. IV and oral contrast material may improve diagnosis of abscess by distinguishing from adjacent bowel. Unenhanced CT with oral contrast is less accurate than contrast-enhanced CT with oral contrast for the characterization of complications of diverticulitis but is superior to unenhanced CT without oral contrast [32]. Combining unenhanced CT with contrast-enhanced CT (biphasic imaging) is unnecessary and not recommended [23]. CT can predict unfavorable outcomes from acute diverticulitis. Longer segments of involved colon, retroperitoneal abscess, and extraluminal air have been associated with recurrence, failure of medical management, and need for surgery.

Left Lower Quadrant Pain. Meta-analyses and prospective studies have demonstrated sensitivity and positive predictive value of graded compression US for diverticulitis of >90%. The accuracy is modestly less than that of CT, but especially so in obese patients and in patients with distal sigmoid diverticulitis. US likely has lower specificity than CT and is less likely to identify an alternative diagnosis. Furthermore, US requires a higher level of training for the diagnosis of diverticulitis than does CT. Dirks et al [25] estimate that a minimum of 500 examinations is required for competency. If used as the initial imaging test at the bedside (eg, point of care), US may hypothetically reduce the number of CT scans performed without a negative effect on patient care, with CT used in inconclusive cases or when the US is negative. US also has the benefit of being noninvasive. Variant 3: Left lower quadrant pain. Suspected complication(s) of diverticulitis. Initial imaging. CT Abdomen and Pelvis CT is the most useful examination for patients with suspected complications of colonic diverticulitis because of its reproducibility, superior diagnostic accuracy [16,19], accuracy for alternative diagnoses with a similar presentation [9,16], risk-stratification of patients for operative versus nonoperative treatment [8,30-32], and inpatient versus outpatient triage [33,34]. IV and oral contrast material may improve diagnosis of abscess by distinguishing from adjacent bowel. Unenhanced CT with oral contrast is less accurate than contrast-enhanced CT with oral contrast for the characterization of complications of diverticulitis but is superior to unenhanced CT without oral contrast [32]. Combining unenhanced CT with contrast-enhanced CT (biphasic imaging) is unnecessary and not recommended [23]. CT can predict unfavorable outcomes from acute diverticulitis. Longer segments of involved colon, retroperitoneal abscess, and extraluminal air have been associated with recurrence, failure of medical management, and need for surgery.

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Additionally, abscess size and size of the inflamed diverticulum(la) may predict longer hospitalization [32,44,45]. Higher C-reactive protein, worse leukocytosis, and advanced age also may be associated with treatment failure [3]. CT can differentiate contained extraluminal air from abscess from spilled feces; this is important for clinical management and surgical decision-making. Small-volume pericolic air (<5 cm from affected segment) can be treated with medical therapy, whereas spilled feces generally requires surgical management [3]. Abscess(es) can be drained through percutaneous US- or CT-guided catheter placement; catheter placement can reduce the need for operative intervention [3,34]. CT- or CT-fluoroscopic guidance may be preferred over US guidance when the abscess(es) is deep or composed predominantly of air [21]. CT also can identify strictures and fistulas. Both often require surgical management and may occur in patients with recurrent or chronic diverticulitis [39,46]. CT Pelvis with Bladder Contrast (CT Cystography) Colovesical fistula is suspected in patients with diverticulitis and concomitant urinary tract infection, fecaluria, or pneumaturia. CT cystography is not usually helpful for the initial evaluation of colovesical fistula. Colovesical fistula can usually be diagnosed at contrast-enhanced CT alone without intracavitary contrast material based on enhancing tract(s) with or without gas extending from the colon to the bladder wall, with or without associated focal bladder wall thickening [47]. CT cystography can provide additional information regarding the size and location of the colovesical fistula in presurgical planning in some cases [48]. Fluoroscopy Contrast Enema Contrast-enhanced enema is not useful as the initial imaging test in patients with suspected diverticulitis because CT is more accurate and easier to obtain [16].

Left Lower Quadrant Pain. Additionally, abscess size and size of the inflamed diverticulum(la) may predict longer hospitalization [32,44,45]. Higher C-reactive protein, worse leukocytosis, and advanced age also may be associated with treatment failure [3]. CT can differentiate contained extraluminal air from abscess from spilled feces; this is important for clinical management and surgical decision-making. Small-volume pericolic air (<5 cm from affected segment) can be treated with medical therapy, whereas spilled feces generally requires surgical management [3]. Abscess(es) can be drained through percutaneous US- or CT-guided catheter placement; catheter placement can reduce the need for operative intervention [3,34]. CT- or CT-fluoroscopic guidance may be preferred over US guidance when the abscess(es) is deep or composed predominantly of air [21]. CT also can identify strictures and fistulas. Both often require surgical management and may occur in patients with recurrent or chronic diverticulitis [39,46]. CT Pelvis with Bladder Contrast (CT Cystography) Colovesical fistula is suspected in patients with diverticulitis and concomitant urinary tract infection, fecaluria, or pneumaturia. CT cystography is not usually helpful for the initial evaluation of colovesical fistula. Colovesical fistula can usually be diagnosed at contrast-enhanced CT alone without intracavitary contrast material based on enhancing tract(s) with or without gas extending from the colon to the bladder wall, with or without associated focal bladder wall thickening [47]. CT cystography can provide additional information regarding the size and location of the colovesical fistula in presurgical planning in some cases [48]. Fluoroscopy Contrast Enema Contrast-enhanced enema is not useful as the initial imaging test in patients with suspected diverticulitis because CT is more accurate and easier to obtain [16].

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Left Lower Quadrant Pain

Contrast-enhanced enema can be used to assess for complications of diverticulitis (eg, fistula) and for presurgical planning before colonic resection (ie, assess length of stricture and colonic motility) [16,32]. Intracavitary contrast Left Lower Quadrant Pain material commonly does not fill colovesical fistula tracts due to their small caliber and insufficient intraluminal pressure. Fluoroscopy Cystography A fluoroscopic cystogram is uncommonly used as an initial imaging test for evaluation of suspected complications of diverticulitis. However, in the setting of potential colovesical fistula following diverticulitis, it may be considered useful in some circumstances as an additional imaging modality, for example, in the setting of preoperative planning, or if the CT findings are ambiguous, and/or based on surgeon preference [47,48]. MRI Abdomen and Pelvis MRI is a second-line imaging examination for suspected complications of diverticulitis. When performed, contrast- enhanced MRI is likely more accurate than unenhanced MRI. Small studies with risk of bias have assessed the diagnostic accuracy of MRI compared to CT. In 2021, Jerjen et al [43] published a systematic review of the use of MRI for the diagnosis of acute colonic diverticulitis. The authors found that the diagnostic accuracy of MRI for diverticulitis is likely less than that of CT but insufficiently studied. Published estimates of diagnostic accuracy have been limited by study-related biases and small sample sizes. At present, there are insufficient published data to support routine use of MRI for the diagnosis of complications of diverticulitis. MRI is less sensitive for extraluminal gas than CT and is more affected by motion artifacts. Motion artifacts are common in severely ill patients. Radiography Abdomen and Pelvis Radiography is not useful as the initial imaging test for the general population of patients with suspected complications from diverticulitis because CT is more accurate.

Left Lower Quadrant Pain. Contrast-enhanced enema can be used to assess for complications of diverticulitis (eg, fistula) and for presurgical planning before colonic resection (ie, assess length of stricture and colonic motility) [16,32]. Intracavitary contrast Left Lower Quadrant Pain material commonly does not fill colovesical fistula tracts due to their small caliber and insufficient intraluminal pressure. Fluoroscopy Cystography A fluoroscopic cystogram is uncommonly used as an initial imaging test for evaluation of suspected complications of diverticulitis. However, in the setting of potential colovesical fistula following diverticulitis, it may be considered useful in some circumstances as an additional imaging modality, for example, in the setting of preoperative planning, or if the CT findings are ambiguous, and/or based on surgeon preference [47,48]. MRI Abdomen and Pelvis MRI is a second-line imaging examination for suspected complications of diverticulitis. When performed, contrast- enhanced MRI is likely more accurate than unenhanced MRI. Small studies with risk of bias have assessed the diagnostic accuracy of MRI compared to CT. In 2021, Jerjen et al [43] published a systematic review of the use of MRI for the diagnosis of acute colonic diverticulitis. The authors found that the diagnostic accuracy of MRI for diverticulitis is likely less than that of CT but insufficiently studied. Published estimates of diagnostic accuracy have been limited by study-related biases and small sample sizes. At present, there are insufficient published data to support routine use of MRI for the diagnosis of complications of diverticulitis. MRI is less sensitive for extraluminal gas than CT and is more affected by motion artifacts. Motion artifacts are common in severely ill patients. Radiography Abdomen and Pelvis Radiography is not useful as the initial imaging test for the general population of patients with suspected complications from diverticulitis because CT is more accurate.

69356

acrac_69420_0

Osteonecrosis PCAs

Osteonecrosis is thought to be a common condition most commonly affecting adults in third to fifth decades of life, with femoral head osteonecrosis incidence reported to be 10,000 to 20,000 new symptomatic cases per year in the United States [4,5]. True prevalence of osteonecrosis is likely quite underestimated because many patients are asymptomatic, especially the metadiaphyseal cases. Recent studies have shown that MR-proven cases of femoral osteonecrosis can be retrospectively visualized on CT abdomen/pelvis with intravenous (IV) contrast performed for other clinical purposes and were originally vastly underreported [6,7]. Risk factors for osteonecrosis are numerous and include trauma, corticosteroid therapy, alcohol use, HIV, lymphoma/leukemia, blood dyscrasias, chemotherapy, radiation therapy, Gaucher disease, and Caisson disease [8-10]. In nontraumatic cases, femoral head osteonecrosis is often bilateral (70%-80%) [5]. Other locations of osteonecrosis (eg, talus, humeral head) are often involved in cases of multifocal osteonecrosis [11,12]. In a long-term follow-up of patients on steroids, Nawata et al [12] found osteonecrosis in the hip (68%), knee (44%), ankle (17%), and shoulder (15%). Many staging systems have been developed for femoral osteonecrosis and often adapted for the humeral head. Ficat and Arlet, developed in the 1960s, does not account for size or location of the necrotic lesion but remains the most commonly used system. Other systems, University of Pennsylvania (Steinberg), Association Research Circulation Osseous (ARCO), and Japanese Orthopedic Association systems, may also be used [15]. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization.

Osteonecrosis PCAs. Osteonecrosis is thought to be a common condition most commonly affecting adults in third to fifth decades of life, with femoral head osteonecrosis incidence reported to be 10,000 to 20,000 new symptomatic cases per year in the United States [4,5]. True prevalence of osteonecrosis is likely quite underestimated because many patients are asymptomatic, especially the metadiaphyseal cases. Recent studies have shown that MR-proven cases of femoral osteonecrosis can be retrospectively visualized on CT abdomen/pelvis with intravenous (IV) contrast performed for other clinical purposes and were originally vastly underreported [6,7]. Risk factors for osteonecrosis are numerous and include trauma, corticosteroid therapy, alcohol use, HIV, lymphoma/leukemia, blood dyscrasias, chemotherapy, radiation therapy, Gaucher disease, and Caisson disease [8-10]. In nontraumatic cases, femoral head osteonecrosis is often bilateral (70%-80%) [5]. Other locations of osteonecrosis (eg, talus, humeral head) are often involved in cases of multifocal osteonecrosis [11,12]. In a long-term follow-up of patients on steroids, Nawata et al [12] found osteonecrosis in the hip (68%), knee (44%), ankle (17%), and shoulder (15%). Many staging systems have been developed for femoral osteonecrosis and often adapted for the humeral head. Ficat and Arlet, developed in the 1960s, does not account for size or location of the necrotic lesion but remains the most commonly used system. Other systems, University of Pennsylvania (Steinberg), Association Research Circulation Osseous (ARCO), and Japanese Orthopedic Association systems, may also be used [15]. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization.

69420

acrac_69420_1

Osteonecrosis PCAs

Reprint requests to: [email protected] Osteonecrosis Noninvasive therapy for osteonecrosis has so far gained limited supporting data. They include statins, bisphosphonates, anticoagulants, extracorporeal shock wave therapy, and hyperbaric oxygen [16-18]. Invasive therapies for early osteonecrosis aim at preventing articular collapse and delaying/preventing the need for joint replacement. Core decompression can be performed in various locations including femoral head, humeral head, and talus. Core decompression can be supplemented with injection of autologous bone marrow cells, vascular fibular grafting, or electric stimulation. However, overall efficacy of core decompression at preventing eventual articular collapse remains controversial [11,19-22]. For late-stage femoral or humeral head osteonecrosis with articular collapse, resurfacing hemiarthroplasty may be needed, whereas total joint arthroplasty is performed in cases of severe secondary osteoarthritis [23]. Femoral head osteonecrosis accounts for 10% of indications for total hip replacements in the United States [24]. For late-stage talar osteonecrosis, talar resection/replacement with arthroplasty or tibiotalar joint fusion may be performed [11]. OR Discussion of Procedures by Variant Variant 1: Clinically suspected osteonecrosis. Initial imaging. The body regions covered in this clinical scenario are chest, pelvis, hip, femur, knee, tibia/fibula, ankle, foot, shoulder, humerus, elbow, forearm, wrist, and hand. Radiography Area of Interest Radiography is beneficial as the initial imaging study for clinically suspected osteonecrosis. Although radiographs are less sensitive for detection of early osteonecrosis, they help to exclude other causes of extremity pain such as fracture, primary arthritis, or tumor. Anteroposterior, lateral (frog-leg lateral for hip), and oblique (eg, ankle/knee) views are recommended to exclude subchondral collapse in cases of epiphyseal osteonecrosis [27,28].

Osteonecrosis PCAs. Reprint requests to: [email protected] Osteonecrosis Noninvasive therapy for osteonecrosis has so far gained limited supporting data. They include statins, bisphosphonates, anticoagulants, extracorporeal shock wave therapy, and hyperbaric oxygen [16-18]. Invasive therapies for early osteonecrosis aim at preventing articular collapse and delaying/preventing the need for joint replacement. Core decompression can be performed in various locations including femoral head, humeral head, and talus. Core decompression can be supplemented with injection of autologous bone marrow cells, vascular fibular grafting, or electric stimulation. However, overall efficacy of core decompression at preventing eventual articular collapse remains controversial [11,19-22]. For late-stage femoral or humeral head osteonecrosis with articular collapse, resurfacing hemiarthroplasty may be needed, whereas total joint arthroplasty is performed in cases of severe secondary osteoarthritis [23]. Femoral head osteonecrosis accounts for 10% of indications for total hip replacements in the United States [24]. For late-stage talar osteonecrosis, talar resection/replacement with arthroplasty or tibiotalar joint fusion may be performed [11]. OR Discussion of Procedures by Variant Variant 1: Clinically suspected osteonecrosis. Initial imaging. The body regions covered in this clinical scenario are chest, pelvis, hip, femur, knee, tibia/fibula, ankle, foot, shoulder, humerus, elbow, forearm, wrist, and hand. Radiography Area of Interest Radiography is beneficial as the initial imaging study for clinically suspected osteonecrosis. Although radiographs are less sensitive for detection of early osteonecrosis, they help to exclude other causes of extremity pain such as fracture, primary arthritis, or tumor. Anteroposterior, lateral (frog-leg lateral for hip), and oblique (eg, ankle/knee) views are recommended to exclude subchondral collapse in cases of epiphyseal osteonecrosis [27,28].

69420

acrac_69420_2

Osteonecrosis PCAs

In late-stage osteonecrosis, radiography will also show findings of secondary osteoarthritis. Bone Scan Area of Interest In recent years, bone scintigraphy has been replaced by MRI for detection of osteonecrosis because of poor spatial resolution, low specificity, and the inability to quantify size of the necrotic lesion [29]. Single-photon emission CT (SPECT) was shown to improve accuracy of bone scintigraphy in a small group of posttransplant patients [30], but radionucleotide scintigraphy is not commonly performed for detection of osteonecrosis. Early limited data for PET/CT have not been shown to useful in diagnosis of early osteonecrosis [31]. More studies are needed to see if PET/CT may be useful in the detection of multifocal osteonecrosis. CT Area of Interest With IV Contrast There is limited evidence to support the use of CT with IV contrast as the initial imaging study for clinically suspected osteonecrosis. Osteonecrosis CT Area of Interest Without and With IV Contrast There is limited evidence to support the use of CT without and with IV contrast as the initial imaging study for clinically suspected osteonecrosis. CT Area of Interest Without IV Contrast There is limited evidence to support the use of CT without IV contrast as the initial imaging study for clinically suspected osteonecrosis. MRI Area of Interest Without and With IV Contrast There is limited evidence to support the use of MRI without and with IV contrast as the initial imaging study for clinically suspected osteonecrosis. MRI Area of Interest Without IV Contrast There is limited evidence to support the use of MRI without IV contrast as the initial imaging study for clinically suspected osteonecrosis. Variant 2: Clinically suspected osteonecrosis. Normal radiographs or radiographs that show findings suspicious for osteonecrosis. Next imaging study. The body regions covered in this clinical scenario are chest, pelvis, hip, femur, knee, tibia/fibula, ankle, foot, shoulder, humerus, elbow, forearm, wrist, and hand.

Osteonecrosis PCAs. In late-stage osteonecrosis, radiography will also show findings of secondary osteoarthritis. Bone Scan Area of Interest In recent years, bone scintigraphy has been replaced by MRI for detection of osteonecrosis because of poor spatial resolution, low specificity, and the inability to quantify size of the necrotic lesion [29]. Single-photon emission CT (SPECT) was shown to improve accuracy of bone scintigraphy in a small group of posttransplant patients [30], but radionucleotide scintigraphy is not commonly performed for detection of osteonecrosis. Early limited data for PET/CT have not been shown to useful in diagnosis of early osteonecrosis [31]. More studies are needed to see if PET/CT may be useful in the detection of multifocal osteonecrosis. CT Area of Interest With IV Contrast There is limited evidence to support the use of CT with IV contrast as the initial imaging study for clinically suspected osteonecrosis. Osteonecrosis CT Area of Interest Without and With IV Contrast There is limited evidence to support the use of CT without and with IV contrast as the initial imaging study for clinically suspected osteonecrosis. CT Area of Interest Without IV Contrast There is limited evidence to support the use of CT without IV contrast as the initial imaging study for clinically suspected osteonecrosis. MRI Area of Interest Without and With IV Contrast There is limited evidence to support the use of MRI without and with IV contrast as the initial imaging study for clinically suspected osteonecrosis. MRI Area of Interest Without IV Contrast There is limited evidence to support the use of MRI without IV contrast as the initial imaging study for clinically suspected osteonecrosis. Variant 2: Clinically suspected osteonecrosis. Normal radiographs or radiographs that show findings suspicious for osteonecrosis. Next imaging study. The body regions covered in this clinical scenario are chest, pelvis, hip, femur, knee, tibia/fibula, ankle, foot, shoulder, humerus, elbow, forearm, wrist, and hand.

69420

acrac_69420_3

Osteonecrosis PCAs

Bone Scan Area of Interest Because of poor spatial resolution, low specificity, and the inability to quantify the size of the necrotic lesion, bone scintigraphy is not beneficial for characterization of osteonecrosis. SPECT may improve the accuracy of bone scintigraphy [30,32,33] for detection of osteonecrosis, but its use has not been widely accepted. In addition, few studies suggest that bone scan may be used to screen for multifocal osteonecrosis [34,35]. CT Area of Interest With IV Contrast There is limited evidence to support the use of CT with IV contrast as the next imaging study for clinically suspected osteonecrosis following radiographs. CT Area of Interest Without and With IV Contrast There is limited evidence to support the use of CT without and with IV contrast as the next imaging study for clinically suspected osteonecrosis following radiographs. CT Area of Interest Without IV Contrast CT is less sensitive than bone scintigraphy and MRI for the detection of early osteonecrosis [36]. Once an insufficiency fracture occurs, CT is superior to MRI in showing location and extent of articular collapse [37,38]. CT also shows osseous details of secondary osteoarthritis well. MRI Area of Interest Without and With IV Contrast MRI with dynamic contrast enhancement has been shown to be useful to differentiate osteonecrosis from transient bone marrow edema syndrome and subchondral insufficiency fracture [39]. Transient bone marrow edema shows subchondral spot of marked hyperperfusion (plasma flow), whereas osteonecrosis shows a rim of high plasma flow surrounding a subchondral area without flow [40]. This rim is thought to represent granulation tissue. Higher slope of enhancement and maximum enhancement in epiphysis was seen in transient bone marrow edema than in subchondral fracture. Osteonecrosis showed overall decreased maximal enhancement [41].

Osteonecrosis PCAs. Bone Scan Area of Interest Because of poor spatial resolution, low specificity, and the inability to quantify the size of the necrotic lesion, bone scintigraphy is not beneficial for characterization of osteonecrosis. SPECT may improve the accuracy of bone scintigraphy [30,32,33] for detection of osteonecrosis, but its use has not been widely accepted. In addition, few studies suggest that bone scan may be used to screen for multifocal osteonecrosis [34,35]. CT Area of Interest With IV Contrast There is limited evidence to support the use of CT with IV contrast as the next imaging study for clinically suspected osteonecrosis following radiographs. CT Area of Interest Without and With IV Contrast There is limited evidence to support the use of CT without and with IV contrast as the next imaging study for clinically suspected osteonecrosis following radiographs. CT Area of Interest Without IV Contrast CT is less sensitive than bone scintigraphy and MRI for the detection of early osteonecrosis [36]. Once an insufficiency fracture occurs, CT is superior to MRI in showing location and extent of articular collapse [37,38]. CT also shows osseous details of secondary osteoarthritis well. MRI Area of Interest Without and With IV Contrast MRI with dynamic contrast enhancement has been shown to be useful to differentiate osteonecrosis from transient bone marrow edema syndrome and subchondral insufficiency fracture [39]. Transient bone marrow edema shows subchondral spot of marked hyperperfusion (plasma flow), whereas osteonecrosis shows a rim of high plasma flow surrounding a subchondral area without flow [40]. This rim is thought to represent granulation tissue. Higher slope of enhancement and maximum enhancement in epiphysis was seen in transient bone marrow edema than in subchondral fracture. Osteonecrosis showed overall decreased maximal enhancement [41].

69420

acrac_69420_4

Osteonecrosis PCAs

MRI Area of Interest Without IV Contrast MRI is the most sensitive and specific imaging modality for the diagnosis of osteonecrosis, with a sensitivity and specificity nearing 100% [24,28,42]. A meta-analysis of 43 studies for early detection of femoral head osteonecrosis reported a sensitivity of 93% and specificity of 91% [43]. MRI allows for characterization of the osteonecrosis including location, volume, and presence of associated bone marrow edema or joint effusion [13,14]. MRI is also important for detecting asymptomatic osteonecrosis in the contralateral hip. Osteonecrosis chondrosarcoma in older adults or chondroblastoma in adolescents). Infarct-associated sarcomas (most commonly malignant fibrous histiocytomas and osteosarcomas) are extremely rare and total up to less than 80 cases in the literature [44,45]. Variant 3: Known osteonecrosis with articular collapse by radiographs. Surgery planned. Next imaging study. The body regions covered in this clinical scenario are ankle, elbow, hip, knee, shoulder, and wrist. Bone Scan Area of Interest There is limited evidence to support the use of bone scan for preoperative planning of osteonecrosis. CT Area of Interest With IV Contrast There is limited evidence to support the use of CT with IV contrast for preoperative planning of osteonecrosis. CT Area of Interest Without and With IV Contrast There is limited evidence to support the use of CT without and with IV contrast for preoperative planning of osteonecrosis. CT Area of Interest Without IV Contrast CT is superior to MRI in showing the location and extent of articular collapse [37,38] and, therefore, plays a critical role in surgical planning. Preoperative CT, before total hip arthroplasty, showed that 21% of femoral head osteonecrosis staged as ARCO stage I or II on radiographs to actually be stage III on CT [49]. With developing technologies in 3-D printing, CT also plays an important role.

Osteonecrosis PCAs. MRI Area of Interest Without IV Contrast MRI is the most sensitive and specific imaging modality for the diagnosis of osteonecrosis, with a sensitivity and specificity nearing 100% [24,28,42]. A meta-analysis of 43 studies for early detection of femoral head osteonecrosis reported a sensitivity of 93% and specificity of 91% [43]. MRI allows for characterization of the osteonecrosis including location, volume, and presence of associated bone marrow edema or joint effusion [13,14]. MRI is also important for detecting asymptomatic osteonecrosis in the contralateral hip. Osteonecrosis chondrosarcoma in older adults or chondroblastoma in adolescents). Infarct-associated sarcomas (most commonly malignant fibrous histiocytomas and osteosarcomas) are extremely rare and total up to less than 80 cases in the literature [44,45]. Variant 3: Known osteonecrosis with articular collapse by radiographs. Surgery planned. Next imaging study. The body regions covered in this clinical scenario are ankle, elbow, hip, knee, shoulder, and wrist. Bone Scan Area of Interest There is limited evidence to support the use of bone scan for preoperative planning of osteonecrosis. CT Area of Interest With IV Contrast There is limited evidence to support the use of CT with IV contrast for preoperative planning of osteonecrosis. CT Area of Interest Without and With IV Contrast There is limited evidence to support the use of CT without and with IV contrast for preoperative planning of osteonecrosis. CT Area of Interest Without IV Contrast CT is superior to MRI in showing the location and extent of articular collapse [37,38] and, therefore, plays a critical role in surgical planning. Preoperative CT, before total hip arthroplasty, showed that 21% of femoral head osteonecrosis staged as ARCO stage I or II on radiographs to actually be stage III on CT [49]. With developing technologies in 3-D printing, CT also plays an important role.

69420

acrac_69424_0

Chronic Foot Pain

Introduction/Background Chronic foot pain is a frequent clinical complaint with approximately 14% to 42% of adults in the United States reporting foot problems, often with significant impact on mobility, difficulty performing daily activities, and increased risk of falling, particularly in older individuals [1,2]. Randomized controlled trials have demonstrated a significant improvement in health-related quality of life with effective treatment of foot pain [3]. Estimating the prevalence of chronic foot pain is challenging, because there is no consensus regarding the definition of chronic pain in the literature. The International Association for the Study of Pain defines chronic pain as any pain persisting past the normal healing time, suggesting 3 months in case of chronic pain of benign causes. Women are more commonly affected, and forefoot conditions are more frequent. Persistent pain for more than 6 years has been reported in 51% of women between 70 to 75 years of age [4]. Because of the wide range of causes of chronic foot pain, assessment of these patients with imaging studies in addition to a dedicated clinical examination is often needed [1]. The guidelines of the American College of Foot and Ankle Surgeons divide heel pain into plantar heel pain, usually related to pathology of the plantar fascia, and posterior heel pain, usually related to pathology of the Achilles tendon, and treatment options vary from nonoperative treatments to surgical procedures [5]. OR Reprint requests to: [email protected] Chronic Foot Pain Discussion of Procedures by Variant Variant 1: Chronic foot pain. Unknown etiology. Initial imaging. Bone Scan Foot There is no relevant literature to support the use of nuclear medicine studies as the first imaging study in the evaluation of chronic foot pain. CT Foot There is no relevant literature to support the use of CT as the first imaging study in the evaluation of chronic foot pain.

Chronic Foot Pain. Introduction/Background Chronic foot pain is a frequent clinical complaint with approximately 14% to 42% of adults in the United States reporting foot problems, often with significant impact on mobility, difficulty performing daily activities, and increased risk of falling, particularly in older individuals [1,2]. Randomized controlled trials have demonstrated a significant improvement in health-related quality of life with effective treatment of foot pain [3]. Estimating the prevalence of chronic foot pain is challenging, because there is no consensus regarding the definition of chronic pain in the literature. The International Association for the Study of Pain defines chronic pain as any pain persisting past the normal healing time, suggesting 3 months in case of chronic pain of benign causes. Women are more commonly affected, and forefoot conditions are more frequent. Persistent pain for more than 6 years has been reported in 51% of women between 70 to 75 years of age [4]. Because of the wide range of causes of chronic foot pain, assessment of these patients with imaging studies in addition to a dedicated clinical examination is often needed [1]. The guidelines of the American College of Foot and Ankle Surgeons divide heel pain into plantar heel pain, usually related to pathology of the plantar fascia, and posterior heel pain, usually related to pathology of the Achilles tendon, and treatment options vary from nonoperative treatments to surgical procedures [5]. OR Reprint requests to: [email protected] Chronic Foot Pain Discussion of Procedures by Variant Variant 1: Chronic foot pain. Unknown etiology. Initial imaging. Bone Scan Foot There is no relevant literature to support the use of nuclear medicine studies as the first imaging study in the evaluation of chronic foot pain. CT Foot There is no relevant literature to support the use of CT as the first imaging study in the evaluation of chronic foot pain.

69424

acrac_69424_1

Chronic Foot Pain

MRI Foot There is no relevant literature to support the use of MRI as the first imaging study in the evaluation of chronic foot pain. Radiography Foot Conventional radiography can be useful to distinguish among different causes of chronic foot pain and is usually the first imaging study in evaluating patients with chronic foot pain. The value of radiographs in the diagnosis of tarsal coalitions has been extensively demonstrated. Overall sensitivities range from 80% to 100% and specificities range from 97% to 98% have been reported for radiographs in the diagnosis of calcaneonavicular coalitions. Most calcaneonavicular coalitions are easily detected on lateral and oblique radiographs of the foot and confirmed on sagittal CT or MRI scans [11]. Talocalcaneal or subtalar coalition may be overlooked on standard foot radiographs due to overlapping structures; however, secondary signs on the lateral view could suggest a subtalar coalition. An overall sensitivity of 100% and a specificity of 88% have been found for radiographs in the diagnosis of talocalcaneal coalitions [12]. CT and MRI remain the most reliable methods for diagnosing subtalar coalitions. Radiographs are usually performed initially in the clinical setting of a suspected stress fracture. A systematic review by Wright et al [13] reported sensitivities ranging from 12% to 56% and specificities ranging from 88% to 96% for radiographs in the detection of lower-extremity stress fractures. Though radiography is typically insensitive in the diagnosis of fasciitis, it should be the initial imaging study in patients with a painful heel. Evidence supports the use of weightbearing radiographs in this instance [5]. The combination of thickened plantar fascia and fat pad abnormalities on radiographs has a sensitivity of 85% and a specificity of 95% for plantar fasciitis [15]. Variant 2: Persistent posttraumatic foot pain. Radiographs negative or equivocal. Clinical concern includes complex regional pain syndrome type I. Next imaging study.

Chronic Foot Pain. MRI Foot There is no relevant literature to support the use of MRI as the first imaging study in the evaluation of chronic foot pain. Radiography Foot Conventional radiography can be useful to distinguish among different causes of chronic foot pain and is usually the first imaging study in evaluating patients with chronic foot pain. The value of radiographs in the diagnosis of tarsal coalitions has been extensively demonstrated. Overall sensitivities range from 80% to 100% and specificities range from 97% to 98% have been reported for radiographs in the diagnosis of calcaneonavicular coalitions. Most calcaneonavicular coalitions are easily detected on lateral and oblique radiographs of the foot and confirmed on sagittal CT or MRI scans [11]. Talocalcaneal or subtalar coalition may be overlooked on standard foot radiographs due to overlapping structures; however, secondary signs on the lateral view could suggest a subtalar coalition. An overall sensitivity of 100% and a specificity of 88% have been found for radiographs in the diagnosis of talocalcaneal coalitions [12]. CT and MRI remain the most reliable methods for diagnosing subtalar coalitions. Radiographs are usually performed initially in the clinical setting of a suspected stress fracture. A systematic review by Wright et al [13] reported sensitivities ranging from 12% to 56% and specificities ranging from 88% to 96% for radiographs in the detection of lower-extremity stress fractures. Though radiography is typically insensitive in the diagnosis of fasciitis, it should be the initial imaging study in patients with a painful heel. Evidence supports the use of weightbearing radiographs in this instance [5]. The combination of thickened plantar fascia and fat pad abnormalities on radiographs has a sensitivity of 85% and a specificity of 95% for plantar fasciitis [15]. Variant 2: Persistent posttraumatic foot pain. Radiographs negative or equivocal. Clinical concern includes complex regional pain syndrome type I. Next imaging study.

69424

acrac_69424_2

Chronic Foot Pain

3-Phase Bone Scan Foot A 3-phase bone scan may be useful in cases of suspected complex regional pain syndrome (CRPS) type I reflex sympathetic dystrophy, and several imaging findings have been described. There is some variation in the literature regarding the diagnostic capabilities of 3-phase bone scan in the diagnosis of CRPS type I. Some authors have found 3-phase bone scan to have higher sensitivity (100%) and negative predictive value (NPV; 100%) when compared to MRI and conventional radiography, and therefore, it may be useful to rule-out disease [16]. A meta-analysis by Cappello et al [17] demonstrated a pooled sensitivity, specificity, NPV, and positive predictive value (PPV) of 78%, Chronic Foot Pain 88%, 88%, and 84%, respectively. There is no relevant literature to support the routine clinical use of nuclear medicine studies in the evaluation of CRPS type II. CT Foot There is no relevant literature to support the use of CT in the evaluation of suspected CRPS. US Foot A few studies addressing the role of US in the diagnosis of CRPS type I reflex sympathetic dystrophy have been published. There is evidence showing that patients who have CRPS type I affecting the lower extremity have increased power Doppler flow compared with asymptomatic control subjects with a sensitivity of 73% and specificity of 92% [22]. Although there is no relevant literature to support the routine clinical use of US in the diagnosis of CRPS type II, high-resolution US may have a role giving its increasing use in nerve assessment [23]. MRI Foot MRI is useful in the diagnosis of several conditions affecting the hallucal sesamoid bones, including fractures, acute and chronic stress related changes, and avascular necrosis, and a variety of MRI findings have been described in the literature [12]. Contrast administration is not routinely performed in the assessment of noninfectious and/or Chronic Foot Pain

Chronic Foot Pain. 3-Phase Bone Scan Foot A 3-phase bone scan may be useful in cases of suspected complex regional pain syndrome (CRPS) type I reflex sympathetic dystrophy, and several imaging findings have been described. There is some variation in the literature regarding the diagnostic capabilities of 3-phase bone scan in the diagnosis of CRPS type I. Some authors have found 3-phase bone scan to have higher sensitivity (100%) and negative predictive value (NPV; 100%) when compared to MRI and conventional radiography, and therefore, it may be useful to rule-out disease [16]. A meta-analysis by Cappello et al [17] demonstrated a pooled sensitivity, specificity, NPV, and positive predictive value (PPV) of 78%, Chronic Foot Pain 88%, 88%, and 84%, respectively. There is no relevant literature to support the routine clinical use of nuclear medicine studies in the evaluation of CRPS type II. CT Foot There is no relevant literature to support the use of CT in the evaluation of suspected CRPS. US Foot A few studies addressing the role of US in the diagnosis of CRPS type I reflex sympathetic dystrophy have been published. There is evidence showing that patients who have CRPS type I affecting the lower extremity have increased power Doppler flow compared with asymptomatic control subjects with a sensitivity of 73% and specificity of 92% [22]. Although there is no relevant literature to support the routine clinical use of US in the diagnosis of CRPS type II, high-resolution US may have a role giving its increasing use in nerve assessment [23]. MRI Foot MRI is useful in the diagnosis of several conditions affecting the hallucal sesamoid bones, including fractures, acute and chronic stress related changes, and avascular necrosis, and a variety of MRI findings have been described in the literature [12]. Contrast administration is not routinely performed in the assessment of noninfectious and/or Chronic Foot Pain

69424

acrac_69424_3

Chronic Foot Pain

nontumoral conditions affecting the hallucal sesamoids; however, it could be useful to distinguish between sesamoiditis and avascular necrosis [32,33]. MRI is widely accepted as the imaging study of choice for diagnosis of plantar plate tears. In a prospective study, Sung et al [40] found high accuracy (96%), sensitivity (95%), specificity (100%), PPV (100%), and NPV (67%) for MRI with surgical correlation. In this study, moderate concordance was found between tear severity on MRI and surgery with greater concordance at higher severity. A meta-analysis showed higher diagnostic accuracy for MRI than US for the detection of plantar plate tears with sensitivity and specificity for MRI of 95% and 54%, respectively [41]. MR arthrography improves visualization of pericapsular structures when compared to conventional MRI and therefore is useful in the diagnosis and characterization of plantar plate tears and abnormalities of related structures [42,43]. US Foot There is limited information available in the literature regarding the use of US in the diagnosis of sesamoiditis. US has been shown to be useful in diagnosing tears of the sesamoid phalangeal ligament in the setting of turf toe [46]. MRI is generally better, but US is also useful in the diagnosis of plantar plate tears. In a cadaveric study, an accuracy, sensitivity, and specificity of 79%, 78%, and 80%, respectively, were found for US [48]. With MRI as the reference standard, Gregg et al [49] showed a sensitivity, specificity, PPV, NPV, and accuracy of 91%, 44%, 93%, 35%, and 85%, respectively, for US in the detection of metatarsophalangeal plantar plate tears in symptomatic subjects. A meta-analysis showed higher diagnostic accuracy for MRI than US for the detection of plantar plate tears. In this meta-analysis the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 93%, 33%, 1.2, and 0.35, respectively, for US [41]. Variant 4: Chronic plantar heel pain. Radiographs negative or equivocal.

Chronic Foot Pain. nontumoral conditions affecting the hallucal sesamoids; however, it could be useful to distinguish between sesamoiditis and avascular necrosis [32,33]. MRI is widely accepted as the imaging study of choice for diagnosis of plantar plate tears. In a prospective study, Sung et al [40] found high accuracy (96%), sensitivity (95%), specificity (100%), PPV (100%), and NPV (67%) for MRI with surgical correlation. In this study, moderate concordance was found between tear severity on MRI and surgery with greater concordance at higher severity. A meta-analysis showed higher diagnostic accuracy for MRI than US for the detection of plantar plate tears with sensitivity and specificity for MRI of 95% and 54%, respectively [41]. MR arthrography improves visualization of pericapsular structures when compared to conventional MRI and therefore is useful in the diagnosis and characterization of plantar plate tears and abnormalities of related structures [42,43]. US Foot There is limited information available in the literature regarding the use of US in the diagnosis of sesamoiditis. US has been shown to be useful in diagnosing tears of the sesamoid phalangeal ligament in the setting of turf toe [46]. MRI is generally better, but US is also useful in the diagnosis of plantar plate tears. In a cadaveric study, an accuracy, sensitivity, and specificity of 79%, 78%, and 80%, respectively, were found for US [48]. With MRI as the reference standard, Gregg et al [49] showed a sensitivity, specificity, PPV, NPV, and accuracy of 91%, 44%, 93%, 35%, and 85%, respectively, for US in the detection of metatarsophalangeal plantar plate tears in symptomatic subjects. A meta-analysis showed higher diagnostic accuracy for MRI than US for the detection of plantar plate tears. In this meta-analysis the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 93%, 33%, 1.2, and 0.35, respectively, for US [41]. Variant 4: Chronic plantar heel pain. Radiographs negative or equivocal.

69424

acrac_69424_4

Chronic Foot Pain

Clinical concern includes plantar fasciitis or plantar fascia tear. Next imaging study. Bone Scan Foot with SPECT or SPECT/CT SPECT/CT has been found to be of use when investigating heel pain with increased specificity when compared to bone scintigraphy alone, because of the improved anatomic localization of metabolic activity. Despite the anatomic and functional advantages of SPECT/CT, MRI and high-frequency US remain the most frequently used imaging modalities in patients with heel pain [50]. A characteristic pattern of abnormal uptake on 3-phase bone scintigraphy has been proven helpful to differentiate plantar fasciitis from calcaneal stress or avulsion fractures [51]. There is no relevant literature to support the routine use of nuclear medicine studies to diagnose plantar fascial tears. Chronic Foot Pain CT Foot There is no relevant literature to support the routine use of CT in the evaluation of a patient with clinical suspicion of pathology of the plantar fascia. MRI Foot MRI allows accurate characterization of the plantar fascia and adjacent soft-tissues and bones, and several imaging findings have been described in patients with plantar fasciitis and partial or complete tears of the plantar fascia on MRI [52]. Given that, some of the findings in patients with plantar fasciitis are nonspecific; these findings can also be seen in asymptomatic patients. MRI should always be correlated with clinical symptoms to avoid overcalling plantar fasciitis. Although no significant differences have been found in plantar fascia thickness on US and MRI, MRI is currently considered the most sensitive imaging study in the diagnosis of plantar fasciitis [53]. There is no relevant literature supporting the routine use of contrast in the diagnosis of plantar fasciitis or tears. US Foot US has shown good sensitivity (80%) and specificity (88%) in the diagnosis of plantar fasciitis when compared to MRI [54].

Chronic Foot Pain. Clinical concern includes plantar fasciitis or plantar fascia tear. Next imaging study. Bone Scan Foot with SPECT or SPECT/CT SPECT/CT has been found to be of use when investigating heel pain with increased specificity when compared to bone scintigraphy alone, because of the improved anatomic localization of metabolic activity. Despite the anatomic and functional advantages of SPECT/CT, MRI and high-frequency US remain the most frequently used imaging modalities in patients with heel pain [50]. A characteristic pattern of abnormal uptake on 3-phase bone scintigraphy has been proven helpful to differentiate plantar fasciitis from calcaneal stress or avulsion fractures [51]. There is no relevant literature to support the routine use of nuclear medicine studies to diagnose plantar fascial tears. Chronic Foot Pain CT Foot There is no relevant literature to support the routine use of CT in the evaluation of a patient with clinical suspicion of pathology of the plantar fascia. MRI Foot MRI allows accurate characterization of the plantar fascia and adjacent soft-tissues and bones, and several imaging findings have been described in patients with plantar fasciitis and partial or complete tears of the plantar fascia on MRI [52]. Given that, some of the findings in patients with plantar fasciitis are nonspecific; these findings can also be seen in asymptomatic patients. MRI should always be correlated with clinical symptoms to avoid overcalling plantar fasciitis. Although no significant differences have been found in plantar fascia thickness on US and MRI, MRI is currently considered the most sensitive imaging study in the diagnosis of plantar fasciitis [53]. There is no relevant literature supporting the routine use of contrast in the diagnosis of plantar fasciitis or tears. US Foot US has shown good sensitivity (80%) and specificity (88%) in the diagnosis of plantar fasciitis when compared to MRI [54].

69424

acrac_69424_5

Chronic Foot Pain

A diagnostic accuracy of 69% for abnormal focal echogenicity within the plantar fascia, 60% for edema around the plantar fascia, 78% for perifascial edema, 69% for rupture of the plantar fascia, and 56% for an associated calcaneal spur have been found for US, using MRI as the reference standard [55]. Kapoor et al [56] showed higher sensitivity and specificity of US elastography when compared to US in the detection of plantar fasciitis (95% and 100% versus 66% and 75%, respectively), using MRI as the reference standard. US has been shown to be useful in the diagnosis of complete and partial tears of the plantar fascia [57]. Some authors regard US to be superior to MRI in differentiating true fiber interruption and tearing of the plantar fascia from edema [58]. Variant 5: Nonradiating chronic midfoot pain of suspected osseous origin. Radiographs negative or equivocal. Clinical concern includes occult fracture, or painful accessory ossicles. Next imaging study. Bone Scan Foot Bone scintigraphy is a sensitive but not specific technique to detect occult fractures because of its capability to detect increased osteoblastic activity. Although bone scans may reveal focal uptake at the site of a radiographically occult fracture, given the anatomical complexity of the foot particularly the midfoot, precise localization may be limited [59]. SPECT/CT may improve the diagnosis of patients with suspected fractures because of the more precise anatomical localization [60]. Symptomatic accessory navicular bones were initially studied with Tc-99m-MDP bone scans and were reported to show increased radiotracer uptake at the synchondrosis, apparently due to the chronic stress reaction [61]. A negative bone scan can exclude the presence of a symptomatic accessory ossicle, but positive findings lack specificity [62]. Isotope bone scans, when combined with CT, may be positive in cases of painful accessory ossicles but remain relatively insensitive for some soft-tissue pathology [63].

Chronic Foot Pain. A diagnostic accuracy of 69% for abnormal focal echogenicity within the plantar fascia, 60% for edema around the plantar fascia, 78% for perifascial edema, 69% for rupture of the plantar fascia, and 56% for an associated calcaneal spur have been found for US, using MRI as the reference standard [55]. Kapoor et al [56] showed higher sensitivity and specificity of US elastography when compared to US in the detection of plantar fasciitis (95% and 100% versus 66% and 75%, respectively), using MRI as the reference standard. US has been shown to be useful in the diagnosis of complete and partial tears of the plantar fascia [57]. Some authors regard US to be superior to MRI in differentiating true fiber interruption and tearing of the plantar fascia from edema [58]. Variant 5: Nonradiating chronic midfoot pain of suspected osseous origin. Radiographs negative or equivocal. Clinical concern includes occult fracture, or painful accessory ossicles. Next imaging study. Bone Scan Foot Bone scintigraphy is a sensitive but not specific technique to detect occult fractures because of its capability to detect increased osteoblastic activity. Although bone scans may reveal focal uptake at the site of a radiographically occult fracture, given the anatomical complexity of the foot particularly the midfoot, precise localization may be limited [59]. SPECT/CT may improve the diagnosis of patients with suspected fractures because of the more precise anatomical localization [60]. Symptomatic accessory navicular bones were initially studied with Tc-99m-MDP bone scans and were reported to show increased radiotracer uptake at the synchondrosis, apparently due to the chronic stress reaction [61]. A negative bone scan can exclude the presence of a symptomatic accessory ossicle, but positive findings lack specificity [62]. Isotope bone scans, when combined with CT, may be positive in cases of painful accessory ossicles but remain relatively insensitive for some soft-tissue pathology [63].

69424

acrac_69424_6

Chronic Foot Pain

CT Foot CT is useful for the detection of radiographically occult fractures. Almeida et al [64] reported visualization of Chopart fractures on CT and/or MRI in one-third of cases initially not diagnosed on radiographs. CT also has utility in the diagnosis of occult fractures involving the subtalar joint as demonstrated in the study by Choi et al [65]. CT is a primary imaging technique in patients with high-energy polytrauma and complex fractures, because radiographs have only poor to moderate sensitivity in this clinical setting [66]. More recently, dual-energy CT has been reported as a useful technique in the detection of bone marrow edema, with excellent performance in the appendicular skeleton, with a sensitivity of 98% and specificity of 93% [67]. This could potentially aid in the detection of radiographically occult fractures. CT may be useful to confirm the presence of an accessory ossicle, os fragmentation or fracture, intra-articular bodies, or osteochondral abnormalities. In contrast to conventional radiographs, CT offers multiplanar capability allowing detailed characterization of the ossicle and the synchondrosis. Assessment of associated soft-tissue pathology or bone marrow edema on CT is limited when compared to MRI [68]. There is no relevant literature supporting the routine use of contrast-enhanced CT images in the diagnosis of occult fractures or symptomatic accessory ossicles, besides a possible use of CT arthrography to demonstrate disruption of the synchondrosis in the setting of os trigonum syndrome [69]. Chronic Foot Pain MRI Foot MRI allows the visualization of bone marrow edema patterns, which improves the detection of fractures in cases of negative or inconclusive radiographs [70]. The utility of MRI in the detection of radiographically occult Chopart fractures has been demonstrated by Almeida et al [64].

Chronic Foot Pain. CT Foot CT is useful for the detection of radiographically occult fractures. Almeida et al [64] reported visualization of Chopart fractures on CT and/or MRI in one-third of cases initially not diagnosed on radiographs. CT also has utility in the diagnosis of occult fractures involving the subtalar joint as demonstrated in the study by Choi et al [65]. CT is a primary imaging technique in patients with high-energy polytrauma and complex fractures, because radiographs have only poor to moderate sensitivity in this clinical setting [66]. More recently, dual-energy CT has been reported as a useful technique in the detection of bone marrow edema, with excellent performance in the appendicular skeleton, with a sensitivity of 98% and specificity of 93% [67]. This could potentially aid in the detection of radiographically occult fractures. CT may be useful to confirm the presence of an accessory ossicle, os fragmentation or fracture, intra-articular bodies, or osteochondral abnormalities. In contrast to conventional radiographs, CT offers multiplanar capability allowing detailed characterization of the ossicle and the synchondrosis. Assessment of associated soft-tissue pathology or bone marrow edema on CT is limited when compared to MRI [68]. There is no relevant literature supporting the routine use of contrast-enhanced CT images in the diagnosis of occult fractures or symptomatic accessory ossicles, besides a possible use of CT arthrography to demonstrate disruption of the synchondrosis in the setting of os trigonum syndrome [69]. Chronic Foot Pain MRI Foot MRI allows the visualization of bone marrow edema patterns, which improves the detection of fractures in cases of negative or inconclusive radiographs [70]. The utility of MRI in the detection of radiographically occult Chopart fractures has been demonstrated by Almeida et al [64].

69424

acrac_69424_7

Chronic Foot Pain

Baker et al [71] analyzed 31 occult fractures involving the ankle and foot in hockey players, finding five occult fractures in the foot, all of which involved the navicular bone. Pierre-Jerome et al [72] found 79% of cuboid fractures in the diabetic population that were radiographically occult using MRI. MRI is also useful in the detection of occult fractures involving the fifth metatarsal bone (Jones fracture) and the subtalar joint [65,73]. There is no evidence in the literature supporting the routine use of contrast in the diagnosis of occult fractures. MRI has replaced bone scans in the evaluation of symptomatic accessory ossicles. MRI allows optimal visualization of the bone marrow within the ossicle and visualization of the synchondrosis. Accessory ossicles may also be associated with tendon pathology, which is also well assessed on MRI [74]. MRI allows clear demonstration of the findings often associated with posterior ankle impingement syndrome [75]. Contrast administration is not routinely performed when assessing symptomatic accessory ossicles on MRI; however, contrast within a disrupted synchondrosis may be demonstrated on MR arthrography studies [69]. US Foot Although not routinely performed, previous studies have demonstrated the role of US in the detection of occult foot fractures. On US, these can be seen as cortical irregularities and are frequently associated with soft-tissue injury in the acute or subacute setting. Wang et al [76] demonstrated 24 cases of radiographically occult ankle and foot fractures in 268 patients. Of these, foot fractures were found most frequently in the calcaneus and metatarsals, and less frequently in the navicular, cuboid, and cuneiform bones. On US, several findings have been reported in cases of painful accessory ossicles, including patients with posterior ankle impingement syndrome; however, optimal characterization of the synchondrosis is difficult on US [62].

Chronic Foot Pain. Baker et al [71] analyzed 31 occult fractures involving the ankle and foot in hockey players, finding five occult fractures in the foot, all of which involved the navicular bone. Pierre-Jerome et al [72] found 79% of cuboid fractures in the diabetic population that were radiographically occult using MRI. MRI is also useful in the detection of occult fractures involving the fifth metatarsal bone (Jones fracture) and the subtalar joint [65,73]. There is no evidence in the literature supporting the routine use of contrast in the diagnosis of occult fractures. MRI has replaced bone scans in the evaluation of symptomatic accessory ossicles. MRI allows optimal visualization of the bone marrow within the ossicle and visualization of the synchondrosis. Accessory ossicles may also be associated with tendon pathology, which is also well assessed on MRI [74]. MRI allows clear demonstration of the findings often associated with posterior ankle impingement syndrome [75]. Contrast administration is not routinely performed when assessing symptomatic accessory ossicles on MRI; however, contrast within a disrupted synchondrosis may be demonstrated on MR arthrography studies [69]. US Foot Although not routinely performed, previous studies have demonstrated the role of US in the detection of occult foot fractures. On US, these can be seen as cortical irregularities and are frequently associated with soft-tissue injury in the acute or subacute setting. Wang et al [76] demonstrated 24 cases of radiographically occult ankle and foot fractures in 268 patients. Of these, foot fractures were found most frequently in the calcaneus and metatarsals, and less frequently in the navicular, cuboid, and cuneiform bones. On US, several findings have been reported in cases of painful accessory ossicles, including patients with posterior ankle impingement syndrome; however, optimal characterization of the synchondrosis is difficult on US [62].

69424

acrac_69465_0

Second and Third Trimester Vaginal Bleeding

The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] Second and Third Trimester Vaginal Bleeding In the setting of premature rupture of membranes, there is a paucity of evidence on whether the introduction of the transvaginal probe may be associated with an increased risk of chorioamnionitis. Carlan et al [19] in a randomized trial of 92 patients did not find any associated increased risk. Nonetheless, caution should be applied in this setting. Special Imaging Considerations Transrectal US is a useful technique and is generally well tolerated when transvaginal and transperineal US are either unsuccessful or declined [20,21]. OR Discussion of Procedures by Variant Variant 1: Second and third trimester vaginal bleeding. Painless bleeding. Initial imaging. US Cervix Transperineal The literature is sparse with regard to defined indications for the use of transperineal US or translabial US among those with painless vaginal bleeding. In current US use, if transabdominal US demonstrates an open cervix with bulging membranes or if the history and physical examination suggests ruptured membranes, then transperineal US might be considered. If transabdominal US is inconclusive and transvaginal US is declined by the patient, transperineal US or transrectal US may be useful for making an accurate diagnosis. US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to any of the other procedures for evaluation of painless vaginal bleeding, it can be invaluable for identification of pathologic entities such as vasa previa [22].

Second and Third Trimester Vaginal Bleeding. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. Reprint requests to: [email protected] Second and Third Trimester Vaginal Bleeding In the setting of premature rupture of membranes, there is a paucity of evidence on whether the introduction of the transvaginal probe may be associated with an increased risk of chorioamnionitis. Carlan et al [19] in a randomized trial of 92 patients did not find any associated increased risk. Nonetheless, caution should be applied in this setting. Special Imaging Considerations Transrectal US is a useful technique and is generally well tolerated when transvaginal and transperineal US are either unsuccessful or declined [20,21]. OR Discussion of Procedures by Variant Variant 1: Second and third trimester vaginal bleeding. Painless bleeding. Initial imaging. US Cervix Transperineal The literature is sparse with regard to defined indications for the use of transperineal US or translabial US among those with painless vaginal bleeding. In current US use, if transabdominal US demonstrates an open cervix with bulging membranes or if the history and physical examination suggests ruptured membranes, then transperineal US might be considered. If transabdominal US is inconclusive and transvaginal US is declined by the patient, transperineal US or transrectal US may be useful for making an accurate diagnosis. US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to any of the other procedures for evaluation of painless vaginal bleeding, it can be invaluable for identification of pathologic entities such as vasa previa [22].

69465

acrac_69465_1

Second and Third Trimester Vaginal Bleeding

Vessels overlying the internal cervical os can be subtle and challenging to diagnose without optimal imaging conditions, and the use of color and spectral Doppler velocimetry US can be essential for making accurate diagnoses and distinguishing fetal from maternal vessels especially with the presence of fetal arterial vessels. US Pregnant Uterus Transabdominal The primary goal of transabdominal US in the setting of painless bleeding is to exclude pathologic etiologies for the bleeding. Impending miscarriage or early labor can typically be excluded via history and physical examination. The most common etiologies for painless vaginal bleeding would be placenta previa, and, less commonly, vasa previa [23]. Transabdominal US is the preferred initial imaging procedure as a screening tool for placenta previa [24]. This evaluation should include visualization of the placenta, the inferior placental margin, the placental umbilical cord insertion, and the cervix from the external os to the internal os. Any vessels overlying the internal cervical os should be specifically excluded. Transabdominal visualization of the lower uterine segment and cervix can be suboptimal because of inadequate urine in the bladder of from shadowing from the maternal symphysis pubis. US Cervix Transperineal The literature is sparse in regard to defined indications for the use of transperineal US among those with painful vaginal bleeding. In current US use, if transabdominal US demonstrates an open cervix with bulging membranes or if the history and physical examination suggests ruptured membranes, then transperineal US might be considered. If transabdominal US is inconclusive and transvaginal US is declined by the patient, transperineal US may be useful for making an accurate diagnosis.

Second and Third Trimester Vaginal Bleeding. Vessels overlying the internal cervical os can be subtle and challenging to diagnose without optimal imaging conditions, and the use of color and spectral Doppler velocimetry US can be essential for making accurate diagnoses and distinguishing fetal from maternal vessels especially with the presence of fetal arterial vessels. US Pregnant Uterus Transabdominal The primary goal of transabdominal US in the setting of painless bleeding is to exclude pathologic etiologies for the bleeding. Impending miscarriage or early labor can typically be excluded via history and physical examination. The most common etiologies for painless vaginal bleeding would be placenta previa, and, less commonly, vasa previa [23]. Transabdominal US is the preferred initial imaging procedure as a screening tool for placenta previa [24]. This evaluation should include visualization of the placenta, the inferior placental margin, the placental umbilical cord insertion, and the cervix from the external os to the internal os. Any vessels overlying the internal cervical os should be specifically excluded. Transabdominal visualization of the lower uterine segment and cervix can be suboptimal because of inadequate urine in the bladder of from shadowing from the maternal symphysis pubis. US Cervix Transperineal The literature is sparse in regard to defined indications for the use of transperineal US among those with painful vaginal bleeding. In current US use, if transabdominal US demonstrates an open cervix with bulging membranes or if the history and physical examination suggests ruptured membranes, then transperineal US might be considered. If transabdominal US is inconclusive and transvaginal US is declined by the patient, transperineal US may be useful for making an accurate diagnosis.

69465

acrac_69465_2

Second and Third Trimester Vaginal Bleeding

US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to any of the other procedures for evaluation of painful vaginal bleeding, it can be invaluable for identification of pathologic entities like placental abruption. An acute clot within the uterus can have an echogenicity similar to that of the placenta; therefore, a placental abruption can be difficult to diagnose, especially prior to organization of the clot [5]. Identification of an area of interest contiguous with the placenta but with no blood flow as documented using color or power Doppler US could suggest the presence of an acute clot as seen with placental abruption. Although color or power Doppler US appears to be helpful with the diagnosis of placental abruption, spectral Doppler US of the fetal arterial vessels appears to be less helpful [27]. US Pregnant Uterus Transabdominal Transabdominal US assessment is the preferred initial procedure for this evaluation and for assessment of the placenta. As in those with painless vaginal bleeding, an evaluation for placenta previa and vasa previa is indicated. The placenta is also comprehensively evaluated to assess its location, the presence of any clot as seen with placental separation in placental abruption, the placental location, and the presence of any vessels overlying the internal cervical os [23,24]. Although US is not sensitive for the diagnosis of placental abruption, the identification of a placental abruption is associated with worse perinatal outcomes [28]. The uterus should be evaluated for signs of uterine rupture, especially among those with a history of prior cesarean delivery. Although uterine rupture is typically a clinical diagnosis, imaging might be helpful in certain cases. Any disruption of the myometrium would suggest a uterine rupture. A threshold of 2.5-mm thickness of the lower uterine segment has been shown to be predictive of uterine dehiscence [29].

Second and Third Trimester Vaginal Bleeding. US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to any of the other procedures for evaluation of painful vaginal bleeding, it can be invaluable for identification of pathologic entities like placental abruption. An acute clot within the uterus can have an echogenicity similar to that of the placenta; therefore, a placental abruption can be difficult to diagnose, especially prior to organization of the clot [5]. Identification of an area of interest contiguous with the placenta but with no blood flow as documented using color or power Doppler US could suggest the presence of an acute clot as seen with placental abruption. Although color or power Doppler US appears to be helpful with the diagnosis of placental abruption, spectral Doppler US of the fetal arterial vessels appears to be less helpful [27]. US Pregnant Uterus Transabdominal Transabdominal US assessment is the preferred initial procedure for this evaluation and for assessment of the placenta. As in those with painless vaginal bleeding, an evaluation for placenta previa and vasa previa is indicated. The placenta is also comprehensively evaluated to assess its location, the presence of any clot as seen with placental separation in placental abruption, the placental location, and the presence of any vessels overlying the internal cervical os [23,24]. Although US is not sensitive for the diagnosis of placental abruption, the identification of a placental abruption is associated with worse perinatal outcomes [28]. The uterus should be evaluated for signs of uterine rupture, especially among those with a history of prior cesarean delivery. Although uterine rupture is typically a clinical diagnosis, imaging might be helpful in certain cases. Any disruption of the myometrium would suggest a uterine rupture. A threshold of 2.5-mm thickness of the lower uterine segment has been shown to be predictive of uterine dehiscence [29].

69465

acrac_69465_3

Second and Third Trimester Vaginal Bleeding

US Pregnant Uterus Transvaginal Transvaginal US is frequently necessary for evaluation of painful vaginal bleeding especially if transabdominal US is inconclusive or inadequate. As with transabdominal US, the evaluation should include visualization of the placenta if identifiable, the inferior placental margin, the presence of any clot within the uterus, the continuity of the myometrium, the cervix from the external os to the internal os, and the identification of any vessels overlying the internal cervical os. Although a transvaginally identified short cervix is well known to be related to preterm delivery, associated vaginal bleeding significantly increases the risk of preterm delivery [30]. Evaluation of the lower uterine segment, the uterine isthmus [31], during transvaginal US can predict bleeding during pregnancy and delivery among those with placenta previa [32]. Variant 3: Second and third trimester vaginal bleeding. Suspicion of or known placental previa, low-lying placental, or vasa previa. Initial imaging. US Cervix Transperineal To our knowledge, there is currently a paucity of literature to support the use of transperineal US for the initial evaluation of placenta previa, low-lying placenta, or vasa previa [33]. US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to transabdominal US and transvaginal US for evaluation of known or suspected placenta previa, low-lying placenta, or vasa previa, it can be invaluable for identification of pathologic Second and Third Trimester Vaginal Bleeding entities like vasa previa. Vessels overlying the internal cervical os can be subtle and challenging to diagnose without optimal imaging conditions, and the use of Doppler velocimetry US can be essential for making this diagnosis [7,34]. Furthermore, spectral Doppler may play an important role in distinguishing fetal arterial vessels from maternal vessels when overlying the internal cervical os.

Second and Third Trimester Vaginal Bleeding. US Pregnant Uterus Transvaginal Transvaginal US is frequently necessary for evaluation of painful vaginal bleeding especially if transabdominal US is inconclusive or inadequate. As with transabdominal US, the evaluation should include visualization of the placenta if identifiable, the inferior placental margin, the presence of any clot within the uterus, the continuity of the myometrium, the cervix from the external os to the internal os, and the identification of any vessels overlying the internal cervical os. Although a transvaginally identified short cervix is well known to be related to preterm delivery, associated vaginal bleeding significantly increases the risk of preterm delivery [30]. Evaluation of the lower uterine segment, the uterine isthmus [31], during transvaginal US can predict bleeding during pregnancy and delivery among those with placenta previa [32]. Variant 3: Second and third trimester vaginal bleeding. Suspicion of or known placental previa, low-lying placental, or vasa previa. Initial imaging. US Cervix Transperineal To our knowledge, there is currently a paucity of literature to support the use of transperineal US for the initial evaluation of placenta previa, low-lying placenta, or vasa previa [33]. US Duplex Doppler Pelvis Although Doppler velocimetry US is an adjunct to transabdominal US and transvaginal US for evaluation of known or suspected placenta previa, low-lying placenta, or vasa previa, it can be invaluable for identification of pathologic Second and Third Trimester Vaginal Bleeding entities like vasa previa. Vessels overlying the internal cervical os can be subtle and challenging to diagnose without optimal imaging conditions, and the use of Doppler velocimetry US can be essential for making this diagnosis [7,34]. Furthermore, spectral Doppler may play an important role in distinguishing fetal arterial vessels from maternal vessels when overlying the internal cervical os.

69465

acrac_69486_0

Orbits Vision and Visual Loss

Introduction/Background A thorough neurologic and ophthalmologic examination can often accurately localize a defect along the visual pathway. Combined with factors such as the age of the patient, the time-course for onset, degree of visual loss at presentation, the presence of eye pain, and visible exophthalmos or enophthalmos determine if imaging is needed, the choice of imaging modality, coverage to include the orbit, anterior skull base and/ or brain, and contrast phase [1]. Disease along the visual pathway may be intrinsically related to the globe, optic nerve, optic chiasm, optic tracts, optic radiations, or primary visual cortex or related to extrinsic mass effect from adjacent pathology upon these structures. Primary diseases of the orbit may present with proptosis, visual disturbance, and/or ophthalmoplegia. These signs and symptoms may occur alone or in combination and may be accompanied by pain or other features including vascular congestion or erythema. The differential diagnosis in adults and subsequent appropriate imaging tests are dependent on the pattern and whether visual loss is monocular or binocular [2]. Imaging analysis of orbital diseases is facilitated by a compartmental approach that establishes a differential diagnosis on the basis of lesion location along the visual pathway [5]. Computed tomography (CT) and magnetic resonance imaging (MRI) are often complementary when assessing visual loss [6,7]. The inherent contrast provided by orbital fat allows for excellent anatomic definition with either technique. Ultrasound (US) and fluorescein angiography are also important diagnostic tools; however, these unique procedures are most often performed by the ophthalmologist and are beyond the scope of this article. Discussion of Procedures by Variant Variant 1: Traumatic visual defect. Suspect orbital injury. Initial imaging.

Orbits Vision and Visual Loss. Introduction/Background A thorough neurologic and ophthalmologic examination can often accurately localize a defect along the visual pathway. Combined with factors such as the age of the patient, the time-course for onset, degree of visual loss at presentation, the presence of eye pain, and visible exophthalmos or enophthalmos determine if imaging is needed, the choice of imaging modality, coverage to include the orbit, anterior skull base and/ or brain, and contrast phase [1]. Disease along the visual pathway may be intrinsically related to the globe, optic nerve, optic chiasm, optic tracts, optic radiations, or primary visual cortex or related to extrinsic mass effect from adjacent pathology upon these structures. Primary diseases of the orbit may present with proptosis, visual disturbance, and/or ophthalmoplegia. These signs and symptoms may occur alone or in combination and may be accompanied by pain or other features including vascular congestion or erythema. The differential diagnosis in adults and subsequent appropriate imaging tests are dependent on the pattern and whether visual loss is monocular or binocular [2]. Imaging analysis of orbital diseases is facilitated by a compartmental approach that establishes a differential diagnosis on the basis of lesion location along the visual pathway [5]. Computed tomography (CT) and magnetic resonance imaging (MRI) are often complementary when assessing visual loss [6,7]. The inherent contrast provided by orbital fat allows for excellent anatomic definition with either technique. Ultrasound (US) and fluorescein angiography are also important diagnostic tools; however, these unique procedures are most often performed by the ophthalmologist and are beyond the scope of this article. Discussion of Procedures by Variant Variant 1: Traumatic visual defect. Suspect orbital injury. Initial imaging.

69486

acrac_69486_1

Orbits Vision and Visual Loss

Patients with traumatic orbital injury may have injuries that are isolated to the orbit or have intracranial manifestations, depending on the mechanism and severity of injury. In the United States, orbital trauma accounts for approximately 3% of visits to the emergency department [8]. Orbital injury should be suspected if periorbital soft-tissue swelling, hyphema, vision loss, or extraocular restriction is present. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. *The views expressed in this manuscript are those of the author and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or United States Government. Reprint requests to: [email protected] Orbits, Vision and Visual Loss Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with trauma and have primarily been supplanted by CT. Variant 2: Nontraumatic orbital asymmetry, exophthalmos, or enophthalmos. Initial imaging. Orbital asymmetry is a broad term that refers to the external appearance of the orbit. This asymmetry may be related to globe position, with one eye perceived or measured as more proptotic compared to the other, or one eye perceived as sunken or retracted compared to the other. Normal range measurements vary and are dependent on the race of the individual [18,19]. Bilateral exophthalmos may indicate an underlying systemic or diffuse condition, such as thyroid eye disease.

Orbits Vision and Visual Loss. Patients with traumatic orbital injury may have injuries that are isolated to the orbit or have intracranial manifestations, depending on the mechanism and severity of injury. In the United States, orbital trauma accounts for approximately 3% of visits to the emergency department [8]. Orbital injury should be suspected if periorbital soft-tissue swelling, hyphema, vision loss, or extraocular restriction is present. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through society representation on expert panels. Participation by representatives from collaborating societies on the expert panel does not necessarily imply individual or society endorsement of the final document. *The views expressed in this manuscript are those of the author and do not reflect the official policy of the Department of Army/Navy/Air Force, Department of Defense, or United States Government. Reprint requests to: [email protected] Orbits, Vision and Visual Loss Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with trauma and have primarily been supplanted by CT. Variant 2: Nontraumatic orbital asymmetry, exophthalmos, or enophthalmos. Initial imaging. Orbital asymmetry is a broad term that refers to the external appearance of the orbit. This asymmetry may be related to globe position, with one eye perceived or measured as more proptotic compared to the other, or one eye perceived as sunken or retracted compared to the other. Normal range measurements vary and are dependent on the race of the individual [18,19]. Bilateral exophthalmos may indicate an underlying systemic or diffuse condition, such as thyroid eye disease.

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Unilateral or asymmetric proptosis is concerning for an underlying mass or pathologic process intrinsic to the globe, optic nerve, extraocular muscles, lacrimal glands, or adjacent soft-tissue structures, posterior to the orbit, within the adjacent skull base or cavernous sinus. Vascular malformations may result in proptosis in adults, and occur anywhere within the orbit. Carotid-cavernous fistula (CCF) may present with proptosis with orbital congestion and chemosis in the setting of an anterior-draining CCF or diplopia and pain in the posterior-draining CCFs [20]. Enophthalmos, or posterior displacement of the globe, may be caused by a development condition resulting in an absent globe (anophthalmia) or small globe (microphthalmia) by traumatic injury to the bony orbit, silent sinus syndrome, processes the extraocular muscles, or by a desmoplastic neoplastic/inflammatory process [9,21-24]. If the asymmetry is associated with a white pupillary reflex (leukocoria), the primary concern is an abnormality localized to the globe. Although leukocoria is a term often used in the pediatric population, this term is not limited to children. Any condition that prevents passage of light through the globe may cause leukocoria, including tumors, developmental processes, and infection [25,26]. Initial evaluation in a patient with leukocoria consists of Patients with disconjugate gaze between the two eyes may also present with orbital asymmetry. These patients may present with diplopia or double vision and is further discussed in Variant 8. MRI In patients with proptosis or if a mass lesion is suspected within the globe, optic nerve, within the adjacent orbital soft tissues, or within the adjacent skull base, an MRI of the orbits without and with contrast is the optimal imaging modality used to localize and characterize the primary lesion [27-30].

Orbits Vision and Visual Loss. Unilateral or asymmetric proptosis is concerning for an underlying mass or pathologic process intrinsic to the globe, optic nerve, extraocular muscles, lacrimal glands, or adjacent soft-tissue structures, posterior to the orbit, within the adjacent skull base or cavernous sinus. Vascular malformations may result in proptosis in adults, and occur anywhere within the orbit. Carotid-cavernous fistula (CCF) may present with proptosis with orbital congestion and chemosis in the setting of an anterior-draining CCF or diplopia and pain in the posterior-draining CCFs [20]. Enophthalmos, or posterior displacement of the globe, may be caused by a development condition resulting in an absent globe (anophthalmia) or small globe (microphthalmia) by traumatic injury to the bony orbit, silent sinus syndrome, processes the extraocular muscles, or by a desmoplastic neoplastic/inflammatory process [9,21-24]. If the asymmetry is associated with a white pupillary reflex (leukocoria), the primary concern is an abnormality localized to the globe. Although leukocoria is a term often used in the pediatric population, this term is not limited to children. Any condition that prevents passage of light through the globe may cause leukocoria, including tumors, developmental processes, and infection [25,26]. Initial evaluation in a patient with leukocoria consists of Patients with disconjugate gaze between the two eyes may also present with orbital asymmetry. These patients may present with diplopia or double vision and is further discussed in Variant 8. MRI In patients with proptosis or if a mass lesion is suspected within the globe, optic nerve, within the adjacent orbital soft tissues, or within the adjacent skull base, an MRI of the orbits without and with contrast is the optimal imaging modality used to localize and characterize the primary lesion [27-30].

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MRI has improved soft tissue characterization, and diffusion-weighted imaging may be particularly useful in situations where lymphoma is a consideration [31]. Although contrast is preferred, an MRI of the orbits without contrast may be appropriate if contrast cannot be given. An MRI of the head without and with contrast may also be added to assess the extent of intracranial disease and to evaluate for distant intracranial metastasis. A CT of the orbits is complementary in assessing orbital lesion characteristics and the extent of disease in this clinical presentation [7]. Orbital inflammatory conditions including thyroid eye disease, IgG4-related disease, and idiopathic orbital inflammatory syndrome may all present with unilateral or bilateral proptosis as a clinical manifestation. Like other orbital conditions, patients with these conditions may be imaged with CT or MRI, and these modalities provide overlapping information related to disease extent. Currently, there is no consensus on the optimal imaging modality to assess patients presenting with idiopathic orbital inflammatory disease or IgG4-related orbital disease. If intracranial extension is suspected, an MRI of the head is the preferred next step in assessment. CT For assessment of orbital asymmetry, CT of the orbits with contrast is complementary to MRI [7]. In the setting of thyroid eye disease, CT provides useful information about orbital, muscle, and fat volumes and osseous anatomy, particularly when orbital decompression is a surgical consideration [7,32-34]. Orbital inflammatory conditions including thyroid eye disease, IgG4-related disease, and idiopathic orbital inflammatory disease may all present with unilateral or bilateral proptosis as a clinical manifestation. Like other orbital conditions, patients with these conditions may be imaged with CT or MRI, and these modalities provide overlapping information related to disease extent.

Orbits Vision and Visual Loss. MRI has improved soft tissue characterization, and diffusion-weighted imaging may be particularly useful in situations where lymphoma is a consideration [31]. Although contrast is preferred, an MRI of the orbits without contrast may be appropriate if contrast cannot be given. An MRI of the head without and with contrast may also be added to assess the extent of intracranial disease and to evaluate for distant intracranial metastasis. A CT of the orbits is complementary in assessing orbital lesion characteristics and the extent of disease in this clinical presentation [7]. Orbital inflammatory conditions including thyroid eye disease, IgG4-related disease, and idiopathic orbital inflammatory syndrome may all present with unilateral or bilateral proptosis as a clinical manifestation. Like other orbital conditions, patients with these conditions may be imaged with CT or MRI, and these modalities provide overlapping information related to disease extent. Currently, there is no consensus on the optimal imaging modality to assess patients presenting with idiopathic orbital inflammatory disease or IgG4-related orbital disease. If intracranial extension is suspected, an MRI of the head is the preferred next step in assessment. CT For assessment of orbital asymmetry, CT of the orbits with contrast is complementary to MRI [7]. In the setting of thyroid eye disease, CT provides useful information about orbital, muscle, and fat volumes and osseous anatomy, particularly when orbital decompression is a surgical consideration [7,32-34]. Orbital inflammatory conditions including thyroid eye disease, IgG4-related disease, and idiopathic orbital inflammatory disease may all present with unilateral or bilateral proptosis as a clinical manifestation. Like other orbital conditions, patients with these conditions may be imaged with CT or MRI, and these modalities provide overlapping information related to disease extent.

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Currently there is no consensus on the optimal imaging modality to assess patients presenting with idiopathic orbital inflammatory disease or IgG4-related orbital disease. CT of the head with contrast may also be added to assess the extent of intracranial disease, particularly if MRI is not available or contraindicated. Precontrast and postcontrast imaging is typically not necessary in evaluating these patients as the precontrast images do not add significant diagnostic information in this scenario. CTA, MRA, Arteriography Vascular structures in and around the orbit may be imaged with CTA, MRA, or catheter-based DSA. Similar to conventional CT and MRI, CTA and MRA may provide complementary information. CTA is performed following the injection of intravascular iodinated contrast and is typically imaged in the arterial phase. MRA can be performed without contrast using the time-of-flight technique or with contrast with an added benefit of producing time-resolved information. Angiographic imaging is helpful in evaluating adults with a suspected vascular anomaly to define high- or low- flow vascular components, vascular supply, and drainage. This may be achieved with MRA, CTA, or DSA. MRA is the preferred method for evaluating these lesions because of the improved soft-tissue lesion characterization with this modality, superior anatomic localization, and the ability to perform time-resolved techniques. If the differential consideration is vascular mass versus malformation, flow characterization may be achieved with time- resolved MRA [35,36]. If a CCF is suspected, noninvasive vascular imaging with MRA and CTA are often indicated for diagnosis confirmation and pretreatment planning. When MRA or CTA is combined with anatomic MRI or CT, the secondary findings associated with CCF, including proptosis, vascular congestion within the orbit, extraocular muscle enlargement, and enlarged superior ophthalmic veins, can be easily identified.

Orbits Vision and Visual Loss. Currently there is no consensus on the optimal imaging modality to assess patients presenting with idiopathic orbital inflammatory disease or IgG4-related orbital disease. CT of the head with contrast may also be added to assess the extent of intracranial disease, particularly if MRI is not available or contraindicated. Precontrast and postcontrast imaging is typically not necessary in evaluating these patients as the precontrast images do not add significant diagnostic information in this scenario. CTA, MRA, Arteriography Vascular structures in and around the orbit may be imaged with CTA, MRA, or catheter-based DSA. Similar to conventional CT and MRI, CTA and MRA may provide complementary information. CTA is performed following the injection of intravascular iodinated contrast and is typically imaged in the arterial phase. MRA can be performed without contrast using the time-of-flight technique or with contrast with an added benefit of producing time-resolved information. Angiographic imaging is helpful in evaluating adults with a suspected vascular anomaly to define high- or low- flow vascular components, vascular supply, and drainage. This may be achieved with MRA, CTA, or DSA. MRA is the preferred method for evaluating these lesions because of the improved soft-tissue lesion characterization with this modality, superior anatomic localization, and the ability to perform time-resolved techniques. If the differential consideration is vascular mass versus malformation, flow characterization may be achieved with time- resolved MRA [35,36]. If a CCF is suspected, noninvasive vascular imaging with MRA and CTA are often indicated for diagnosis confirmation and pretreatment planning. When MRA or CTA is combined with anatomic MRI or CT, the secondary findings associated with CCF, including proptosis, vascular congestion within the orbit, extraocular muscle enlargement, and enlarged superior ophthalmic veins, can be easily identified.

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DSA is performed for more detailed assessment and intervention in patients with confirmed CCFs or in patients with a high index of suspicion for CCFs not confirmed on noninvasive imaging [37]. Although DSA is considered the gold standard for imaging Orbits, Vision and Visual Loss evaluation and treatment and may be appropriate in the acute assessment of acute visual loss related to suspected CCF, it is relatively invasive and carries its own procedural risks and is typically not performed as the initial test. In addition, DSA lacks in the ability to provide regional soft-tissue information seen with cross-sectional imaging that may assist in making the diagnosis. In a retrospective comparative analysis between CTA, MRA, and DSA, CTA was shown to be as useful as DSA for CCF detection in a cohort of 53 patients [20]. MRA was slightly less successful but still determined as good by demonstrating CCFs in approximately 80% of cases [20]. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with proptosis and have primarily been supplanted by CT. Variant 3: Suspected orbital cellulitis, uveitis, or scleritis. Initial imaging. Patients presenting with symptoms and signs of orbital cellulitis (postseptal cellulitis) are often referred for imaging to assess for complications including intraorbital abscess, intracranial involvement, and vascular compromise. The source of this infection is often from the adjacent paranasal sinuses and may be viral, bacterial, or fungal [38]. Idiopathic other (IOIS), inflammatory/granulomatous processes are potential clinical and imaging mimics for orbital cellulitis. IOIS, previously known as orbital pseudotumor, may present with signs and symptoms that mimic infection and is a diagnosis of exclusion. IgG4-related orbital disease is a relatively recently described inflammatory condition that may account for a significant percentage of patients that have been previously described as idiopathic [39-41].

Orbits Vision and Visual Loss. DSA is performed for more detailed assessment and intervention in patients with confirmed CCFs or in patients with a high index of suspicion for CCFs not confirmed on noninvasive imaging [37]. Although DSA is considered the gold standard for imaging Orbits, Vision and Visual Loss evaluation and treatment and may be appropriate in the acute assessment of acute visual loss related to suspected CCF, it is relatively invasive and carries its own procedural risks and is typically not performed as the initial test. In addition, DSA lacks in the ability to provide regional soft-tissue information seen with cross-sectional imaging that may assist in making the diagnosis. In a retrospective comparative analysis between CTA, MRA, and DSA, CTA was shown to be as useful as DSA for CCF detection in a cohort of 53 patients [20]. MRA was slightly less successful but still determined as good by demonstrating CCFs in approximately 80% of cases [20]. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with proptosis and have primarily been supplanted by CT. Variant 3: Suspected orbital cellulitis, uveitis, or scleritis. Initial imaging. Patients presenting with symptoms and signs of orbital cellulitis (postseptal cellulitis) are often referred for imaging to assess for complications including intraorbital abscess, intracranial involvement, and vascular compromise. The source of this infection is often from the adjacent paranasal sinuses and may be viral, bacterial, or fungal [38]. Idiopathic other (IOIS), inflammatory/granulomatous processes are potential clinical and imaging mimics for orbital cellulitis. IOIS, previously known as orbital pseudotumor, may present with signs and symptoms that mimic infection and is a diagnosis of exclusion. IgG4-related orbital disease is a relatively recently described inflammatory condition that may account for a significant percentage of patients that have been previously described as idiopathic [39-41].

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Manifestations include eyelid or periocular swelling, lacrimal gland enlargement, extraocular muscle involvement, intraorbital mass, proptosis, and cranial nerve V involvement. CT CT of the orbits with contrast is often the initial imaging modality in the emergent setting for suspected infection [2,7,42,43]. CT is superior to MRI for foreign body assessment, calcification detection, and osseous evaluation [43]. CT can be used in conjunction with the Chandler criteria to evaluate for the presence of bone erosion and subperiosteal abscess, which may require surgical intervention [38,44-46]. Imaging findings may show bone erosion on CT, opacification of a neighboring infected sinus, and/or intraorbital extension of inflammatory disease [47]. In patients who cannot receive contrast, a noncontrast orbit CT may still add useful information. Precontrast and postcontrast imaging is typically not necessary in evaluating these patients as the precontrast images do not add significant diagnostic information in this scenario. Currently there is no consensus on the optimal imaging modality to assess patients presenting with IOIS or IgG4- related orbital disease. Orbital CT and MRI are often complementary in their roles. Signs of inflammation may be detected with CT or MRI, which show intraconal or extraconal soft-tissue lesions that are diffuse or localized and commonly involve the orbital apex [43,48]. These findings may be initially seen on CT and subsequently further evaluated with MRI for improved soft-tissue characterization. MRI Orbital MRI is complementary to CT in evaluating intraorbital spread of infection. An MRI of the orbits without and with contrast should be considered if a more detailed assessment of intraorbital spread of infection is clinically warranted. In patients with suspected intracranial extension or complications, an MRI of the brain with high-resolution images to include the cavernous sinuses [2,42,43,46,47] provides greater soft-tissue resolution than CT.

Orbits Vision and Visual Loss. Manifestations include eyelid or periocular swelling, lacrimal gland enlargement, extraocular muscle involvement, intraorbital mass, proptosis, and cranial nerve V involvement. CT CT of the orbits with contrast is often the initial imaging modality in the emergent setting for suspected infection [2,7,42,43]. CT is superior to MRI for foreign body assessment, calcification detection, and osseous evaluation [43]. CT can be used in conjunction with the Chandler criteria to evaluate for the presence of bone erosion and subperiosteal abscess, which may require surgical intervention [38,44-46]. Imaging findings may show bone erosion on CT, opacification of a neighboring infected sinus, and/or intraorbital extension of inflammatory disease [47]. In patients who cannot receive contrast, a noncontrast orbit CT may still add useful information. Precontrast and postcontrast imaging is typically not necessary in evaluating these patients as the precontrast images do not add significant diagnostic information in this scenario. Currently there is no consensus on the optimal imaging modality to assess patients presenting with IOIS or IgG4- related orbital disease. Orbital CT and MRI are often complementary in their roles. Signs of inflammation may be detected with CT or MRI, which show intraconal or extraconal soft-tissue lesions that are diffuse or localized and commonly involve the orbital apex [43,48]. These findings may be initially seen on CT and subsequently further evaluated with MRI for improved soft-tissue characterization. MRI Orbital MRI is complementary to CT in evaluating intraorbital spread of infection. An MRI of the orbits without and with contrast should be considered if a more detailed assessment of intraorbital spread of infection is clinically warranted. In patients with suspected intracranial extension or complications, an MRI of the brain with high-resolution images to include the cavernous sinuses [2,42,43,46,47] provides greater soft-tissue resolution than CT.

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A high index of suspicion and low threshold for MRI is needed if invasive fungal infection is of concern in an immunocompromised patient [42,46,47] because of the morbidity of the disease. Although contrast is preferred, in patients who cannot receive contrast, a noncontrast orbital MRI may provide useful information. Orbits, Vision and Visual Loss CTA, MRA, Arteriography CTA or MRA may be added to routine CT or MRI scans if there is a suspicion for vascular invasion including cavernous sinus thrombosis, particularly in the setting of fungal disease. MRA may be performed without and/or with contrast. In the setting of cavernous sinus thrombosis, a contrast-enhanced MRA may provide additional information not provided by a traditional noncontrast MRA examination. There is a limited role for DSA in evaluating patients with orbital infection. Radiography Orbital radiographs are insufficient to detect orbital cellulitis. Radiographs have largely been supplanted by CT when imaging is necessary [49]. Variant 4: Suspected optic neuritis. Initial imaging. Optic neuritis is defined as an acute inflammatory condition of the optic nerve, and can be unilateral or bilateral. It often presents with painful visual loss [50] but can also be painless. The primary differential consideration includes multiple other optica, infectious/granulomatous conditions. Although optic neuritis can be idiopathic, it is often seen as the initial manifestation of multiple sclerosis. MRI In patients presenting with a clinical suspicion for optic neuritis, both MRI of the orbits and MRI of the head without and with contrast are the primary imaging studies for initial assessment. This serves two primary purposes. The first purpose is to evaluate for abnormal enhancement and signal changes within the optic nerve, and the second is to evaluate the brain for associated intracranial demyelinating lesions, as the latter is a strong predictor of the subsequent development of multiple sclerosis [50-52].

Orbits Vision and Visual Loss. A high index of suspicion and low threshold for MRI is needed if invasive fungal infection is of concern in an immunocompromised patient [42,46,47] because of the morbidity of the disease. Although contrast is preferred, in patients who cannot receive contrast, a noncontrast orbital MRI may provide useful information. Orbits, Vision and Visual Loss CTA, MRA, Arteriography CTA or MRA may be added to routine CT or MRI scans if there is a suspicion for vascular invasion including cavernous sinus thrombosis, particularly in the setting of fungal disease. MRA may be performed without and/or with contrast. In the setting of cavernous sinus thrombosis, a contrast-enhanced MRA may provide additional information not provided by a traditional noncontrast MRA examination. There is a limited role for DSA in evaluating patients with orbital infection. Radiography Orbital radiographs are insufficient to detect orbital cellulitis. Radiographs have largely been supplanted by CT when imaging is necessary [49]. Variant 4: Suspected optic neuritis. Initial imaging. Optic neuritis is defined as an acute inflammatory condition of the optic nerve, and can be unilateral or bilateral. It often presents with painful visual loss [50] but can also be painless. The primary differential consideration includes multiple other optica, infectious/granulomatous conditions. Although optic neuritis can be idiopathic, it is often seen as the initial manifestation of multiple sclerosis. MRI In patients presenting with a clinical suspicion for optic neuritis, both MRI of the orbits and MRI of the head without and with contrast are the primary imaging studies for initial assessment. This serves two primary purposes. The first purpose is to evaluate for abnormal enhancement and signal changes within the optic nerve, and the second is to evaluate the brain for associated intracranial demyelinating lesions, as the latter is a strong predictor of the subsequent development of multiple sclerosis [50-52].

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MRI is incorporated into the revised McDonald criteria and MAGNIMS consensus guidelines [53] for diagnosing multiple sclerosis, which is characterized by establishing dissemination of lesions in space and time [51]. Neuromyelitis optica is a demyelinating condition that typically affects the optic nerves and spinal cord and is best assessed with MRI [54]. Serum and cerebrospinal fluid laboratory tests may also be useful in differentiating between these two entities [51,55]. CT Although an imaging test of the brain may be indicated prior to lumbar puncture in patients with optic disc edema to exclude a space occupying mass, CT imaging of the head is typically not indicated specifically for the evaluation of a patient with optic neuritis. CTA, MRA, Arteriography Angiography is not routinely used in the initial evaluation of optic neuritis. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with clinical concern for vision loss. MRI MRI is not routinely used in the evaluation of non-neoplastic ocular processes. In patients with glaucoma, a primary cause of irreversible blindness, there has been interest in applying advanced MRI techniques to earlier detection of this disease process; however, additional research is needed to validate the utility of these advanced techniques [56]. Orbits, Vision and Visual Loss CT CT is not routinely used in the evaluation of nontraumatic, noninfectious, or non-neoplastic ocular processes. CTA, MRA, Arteriography CTA, MRA, and DSA are not first-line tests in this scenario. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with vision loss. Variant 6: Visual loss. Intraocular mass, optic nerve, or pre-chiasm symptoms. Initial imaging. Monocular visual loss may be due to an intraocular mass, such as melanoma [57], or may involve the intraorbital, intracanalicular, or pre-chiasm segments of the optic nerve.

Orbits Vision and Visual Loss. MRI is incorporated into the revised McDonald criteria and MAGNIMS consensus guidelines [53] for diagnosing multiple sclerosis, which is characterized by establishing dissemination of lesions in space and time [51]. Neuromyelitis optica is a demyelinating condition that typically affects the optic nerves and spinal cord and is best assessed with MRI [54]. Serum and cerebrospinal fluid laboratory tests may also be useful in differentiating between these two entities [51,55]. CT Although an imaging test of the brain may be indicated prior to lumbar puncture in patients with optic disc edema to exclude a space occupying mass, CT imaging of the head is typically not indicated specifically for the evaluation of a patient with optic neuritis. CTA, MRA, Arteriography Angiography is not routinely used in the initial evaluation of optic neuritis. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with clinical concern for vision loss. MRI MRI is not routinely used in the evaluation of non-neoplastic ocular processes. In patients with glaucoma, a primary cause of irreversible blindness, there has been interest in applying advanced MRI techniques to earlier detection of this disease process; however, additional research is needed to validate the utility of these advanced techniques [56]. Orbits, Vision and Visual Loss CT CT is not routinely used in the evaluation of nontraumatic, noninfectious, or non-neoplastic ocular processes. CTA, MRA, Arteriography CTA, MRA, and DSA are not first-line tests in this scenario. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with vision loss. Variant 6: Visual loss. Intraocular mass, optic nerve, or pre-chiasm symptoms. Initial imaging. Monocular visual loss may be due to an intraocular mass, such as melanoma [57], or may involve the intraorbital, intracanalicular, or pre-chiasm segments of the optic nerve.

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This includes lesions intrinsic to the nerve, such as an optic nerve glioma, or extrinsic to the nerve resulting in mass effect, such as an optic nerve sheath meningioma. The differential diagnosis varies based on the age of the patient. MRI MRI provides excellent soft-tissue resolution of structures within the orbit, including the globe, muscles, tendons, nerves, and vascular structures. MRI of the orbits without and with contrast is the preferred modality in evaluating soft-tissue pathology within and around the orbit, particularly in mass characterization, optic nerve pathology, and assessing disease within the globe and orbit [1,7,58]. If contrast cannot be given, a noncontrast orbit MR may still provide useful information. If there is a significant intracranial component, additional MRI of the brain without and with contrast may be indicated to evaluate for intracranial spread of disease. CT CT is superior to MRI for foreign body assessment, calcification detection, and osseous evaluation [43]. Orbital CT is complementary to MRI in evaluating patients with ocular, orbital, and skull base neoplasms. In patients presenting with clinical suspicion for an intraorbital mass lesion, orbital CT with contrast may be complementary to MRI in providing additional information about adjacent bone involvement, including bone erosion, sclerosis, or periosteal reaction that may not be readily seen with MRI [2,7]. If contrast cannot be given, a noncontrast orbit CT may still add useful information. CT imaging of the head with contrast may also be appropriate if more extensive skull or skull-base involvement is suspected. Precontrast and postcontrast orbital imaging is typically not necessary in evaluating these patients as the precontrast images do not add significant diagnostic information in this scenario. CTA, MRA, Arteriography CTA or MRA are complementary and may be added to routine CT or MRI scans if there is a suspicion for an intraorbital vascular lesion [35,36].

Orbits Vision and Visual Loss. This includes lesions intrinsic to the nerve, such as an optic nerve glioma, or extrinsic to the nerve resulting in mass effect, such as an optic nerve sheath meningioma. The differential diagnosis varies based on the age of the patient. MRI MRI provides excellent soft-tissue resolution of structures within the orbit, including the globe, muscles, tendons, nerves, and vascular structures. MRI of the orbits without and with contrast is the preferred modality in evaluating soft-tissue pathology within and around the orbit, particularly in mass characterization, optic nerve pathology, and assessing disease within the globe and orbit [1,7,58]. If contrast cannot be given, a noncontrast orbit MR may still provide useful information. If there is a significant intracranial component, additional MRI of the brain without and with contrast may be indicated to evaluate for intracranial spread of disease. CT CT is superior to MRI for foreign body assessment, calcification detection, and osseous evaluation [43]. Orbital CT is complementary to MRI in evaluating patients with ocular, orbital, and skull base neoplasms. In patients presenting with clinical suspicion for an intraorbital mass lesion, orbital CT with contrast may be complementary to MRI in providing additional information about adjacent bone involvement, including bone erosion, sclerosis, or periosteal reaction that may not be readily seen with MRI [2,7]. If contrast cannot be given, a noncontrast orbit CT may still add useful information. CT imaging of the head with contrast may also be appropriate if more extensive skull or skull-base involvement is suspected. Precontrast and postcontrast orbital imaging is typically not necessary in evaluating these patients as the precontrast images do not add significant diagnostic information in this scenario. CTA, MRA, Arteriography CTA or MRA are complementary and may be added to routine CT or MRI scans if there is a suspicion for an intraorbital vascular lesion [35,36].

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MRA without and with contrast may be preferred over CTA if time-resolved information is needed in lesion characterization. DSA is not a first-line test in this scenario. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with monocular vision loss. Variant 7: Nonischemic visual loss. Chiasm or post-chiasm symptoms. Initial imaging. If a patient presents with a junctional scotoma or bitemporal hemianopia, a parasellar lesion is suspected, with mass effect on the optic chiasm affecting the crossing temporal fibers. Lesions may arise from the pituitary gland, hypothalamus, or adjacent dura, and accompanying endocrine abnormalities may also be present. Slowly progressive binocular visual defect findings suggest an intracranial or skull-base abnormality, including primary neoplasms and metastatic lesions. Mass effect from other intracranial pathology, including abscess, multiple sclerosis, or vascular lesions such as arteriovenous malformations and cerebral aneurysms, may also present with a similar visual field deficit. Orbits, Vision and Visual Loss MRI Patients with a junctional scotoma or bitemporal visual defect are best assessed with an MRI of the brain without and with contrast, which includes the thin-slice profile needed to evaluate the pituitary gland and any suprasellar mass effect [43]. Detailed assessment of the optic chiasm and its relationship to an underlying mass are easily seen with an MRI of the brain without and with contrast. If contrast cannot be given, an MRI of the brain without contrast may be appropriate. Patients presenting with a homonymous hemianopia or quadrantanopia defect are best assessed with an MRI of the brain without and with contrast [2,7,59-61]. Because the defect is most likely in a post-chiasm location, additional smaller field-of-view images of the orbit are typically not necessary.

Orbits Vision and Visual Loss. MRA without and with contrast may be preferred over CTA if time-resolved information is needed in lesion characterization. DSA is not a first-line test in this scenario. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with monocular vision loss. Variant 7: Nonischemic visual loss. Chiasm or post-chiasm symptoms. Initial imaging. If a patient presents with a junctional scotoma or bitemporal hemianopia, a parasellar lesion is suspected, with mass effect on the optic chiasm affecting the crossing temporal fibers. Lesions may arise from the pituitary gland, hypothalamus, or adjacent dura, and accompanying endocrine abnormalities may also be present. Slowly progressive binocular visual defect findings suggest an intracranial or skull-base abnormality, including primary neoplasms and metastatic lesions. Mass effect from other intracranial pathology, including abscess, multiple sclerosis, or vascular lesions such as arteriovenous malformations and cerebral aneurysms, may also present with a similar visual field deficit. Orbits, Vision and Visual Loss MRI Patients with a junctional scotoma or bitemporal visual defect are best assessed with an MRI of the brain without and with contrast, which includes the thin-slice profile needed to evaluate the pituitary gland and any suprasellar mass effect [43]. Detailed assessment of the optic chiasm and its relationship to an underlying mass are easily seen with an MRI of the brain without and with contrast. If contrast cannot be given, an MRI of the brain without contrast may be appropriate. Patients presenting with a homonymous hemianopia or quadrantanopia defect are best assessed with an MRI of the brain without and with contrast [2,7,59-61]. Because the defect is most likely in a post-chiasm location, additional smaller field-of-view images of the orbit are typically not necessary.

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CT For lesion characterization in and around the sella, CT of the head may be complementary to MRI and add additional information on the characteristics of the lesion, including the presence of calcification such as in a craniopharyngioma [7,59,62]. In patients with post-chiasm symptoms, an MRI of the brain is typically preferred over CT, particularly in a subacute, slowly progressive presentation. In the acute setting, a noncontrast head CT is reasonable for initial imaging. If a patient is unable or unwilling to have MRI, then a CT of the head without and with contrast may be an appropriate alternative. If a mass such as a meningioma is identified in close proximity to the sagittal sinus, additional MRV or CTV imaging may be indicated to assess the integrity of the dural venous sinus. Postcontrast MRV and CTV are complementary in their utility in evaluating the dural venous sinuses. Noncontrast MRV may be performed in the event that contrast cannot be administered. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with vision loss. Variant 8: Ophthalmoplegia or diplopia. Initial imaging. Ophthalmoplegia is paralysis of one or more extraocular muscles. This may be caused by impaired motility of the muscles, disrupted nerve conduction along the neuromuscular junction, or from denervation of the affected cranial nerve or brainstem nucleus. Ophthalmoplegia may also be related to granulomatous, inflammatory, neoplastic, and traumatic abnormalities that primarily affect the extraocular muscles. Traumatic orbital injury is covered in Variant 1 of this document. Patients with isolated cranial nerve III palsies can be divided into pupil-involving or pupil-sparing, suggesting vascular compression versus vasculopathic etiologies, respectively. Isolated cranial nerve IV palsies are most often caused by trauma [63] and rarely nerve sheath tumors. Isolated cranial nerve VI palsies may be caused by Orbits, Vision and Visual Loss

Orbits Vision and Visual Loss. CT For lesion characterization in and around the sella, CT of the head may be complementary to MRI and add additional information on the characteristics of the lesion, including the presence of calcification such as in a craniopharyngioma [7,59,62]. In patients with post-chiasm symptoms, an MRI of the brain is typically preferred over CT, particularly in a subacute, slowly progressive presentation. In the acute setting, a noncontrast head CT is reasonable for initial imaging. If a patient is unable or unwilling to have MRI, then a CT of the head without and with contrast may be an appropriate alternative. If a mass such as a meningioma is identified in close proximity to the sagittal sinus, additional MRV or CTV imaging may be indicated to assess the integrity of the dural venous sinus. Postcontrast MRV and CTV are complementary in their utility in evaluating the dural venous sinuses. Noncontrast MRV may be performed in the event that contrast cannot be administered. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with vision loss. Variant 8: Ophthalmoplegia or diplopia. Initial imaging. Ophthalmoplegia is paralysis of one or more extraocular muscles. This may be caused by impaired motility of the muscles, disrupted nerve conduction along the neuromuscular junction, or from denervation of the affected cranial nerve or brainstem nucleus. Ophthalmoplegia may also be related to granulomatous, inflammatory, neoplastic, and traumatic abnormalities that primarily affect the extraocular muscles. Traumatic orbital injury is covered in Variant 1 of this document. Patients with isolated cranial nerve III palsies can be divided into pupil-involving or pupil-sparing, suggesting vascular compression versus vasculopathic etiologies, respectively. Isolated cranial nerve IV palsies are most often caused by trauma [63] and rarely nerve sheath tumors. Isolated cranial nerve VI palsies may be caused by Orbits, Vision and Visual Loss

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lesions within the prepontine cistern, skull base, cavernous sinus, or sella. Isolated cranial nerve VI palsies may also be seen in the setting of increased intracranial pressure without direct compression of the nerve [64]. Multiple ipsilateral cranial nerve palsies that affect cranial nerves III, IV, and VI suggest a lesion at the cavernous sinus or orbital apex [65] and can occur with pathology in the basilar subarachnoid space, as seen in infectious meningitis (TB, fungal, Lyme disease) or noninfectious causes (sarcoid, neoplasm, perineural, or leptomeningeal tumor spread). In patients with internuclear ophthalmoplegia, a brain-stem lesion affecting the medial longitudinal fasciculus should be suspected. A demyelinating plaque in the setting of multiple sclerosis is a primary consideration in younger patients and stroke in older patients presenting with an acute internuclear ophthalmoplegia [66]. Other likely considerations include tumor, hemorrhage, and infection [66]. MRI MRI of the orbits without and with contrast is preferred [67] if ophthalmoplegia is felt to be related to a primary disease process within the orbit affecting the extraocular muscles or if there is history of trauma, enophthalmos, proptosis, orbital inflammation, or chemosis. An MRI of the orbits with the globes imaged during different gaze positions may aid in identifying a potential muscular slip or pulley abnormality [68]. CT In patients with ophthalmoplegia or diplopia with associated secondary signs of proptosis, orbital inflammation, or trauma, a dedicated orbit CT is typically indicated to evaluate the extraocular muscles. Contrast is often indicated in the setting of orbital inflammation assessment but not indicated in the acute traumatic setting, as specified in Variant 1. CT is superior to MRI for foreign body assessment, calcification detection, and osseous evaluation [43].

Orbits Vision and Visual Loss. lesions within the prepontine cistern, skull base, cavernous sinus, or sella. Isolated cranial nerve VI palsies may also be seen in the setting of increased intracranial pressure without direct compression of the nerve [64]. Multiple ipsilateral cranial nerve palsies that affect cranial nerves III, IV, and VI suggest a lesion at the cavernous sinus or orbital apex [65] and can occur with pathology in the basilar subarachnoid space, as seen in infectious meningitis (TB, fungal, Lyme disease) or noninfectious causes (sarcoid, neoplasm, perineural, or leptomeningeal tumor spread). In patients with internuclear ophthalmoplegia, a brain-stem lesion affecting the medial longitudinal fasciculus should be suspected. A demyelinating plaque in the setting of multiple sclerosis is a primary consideration in younger patients and stroke in older patients presenting with an acute internuclear ophthalmoplegia [66]. Other likely considerations include tumor, hemorrhage, and infection [66]. MRI MRI of the orbits without and with contrast is preferred [67] if ophthalmoplegia is felt to be related to a primary disease process within the orbit affecting the extraocular muscles or if there is history of trauma, enophthalmos, proptosis, orbital inflammation, or chemosis. An MRI of the orbits with the globes imaged during different gaze positions may aid in identifying a potential muscular slip or pulley abnormality [68]. CT In patients with ophthalmoplegia or diplopia with associated secondary signs of proptosis, orbital inflammation, or trauma, a dedicated orbit CT is typically indicated to evaluate the extraocular muscles. Contrast is often indicated in the setting of orbital inflammation assessment but not indicated in the acute traumatic setting, as specified in Variant 1. CT is superior to MRI for foreign body assessment, calcification detection, and osseous evaluation [43].

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Although CT imaging of the orbits is preferred, CT imaging of the head may be appropriate if an intracranial abnormality is suspected. Precontrast and postcontrast imaging of the orbits is typically not necessary in evaluating these patients as the precontrast images do not add significant diagnostic information in this scenario. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with proptosis and have primarily been supplanted by CT. Summary of Recommendations Orbital trauma is best assessed with a noncontrast orbit CT and/or noncontrast CT of the head, which are often complementary. Orbital asymmetry, exophthalmos, or enophthalmos can be evaluated with contrast-enhanced orbit CT or contrast-enhanced orbit MRI, which are often complementary. Contrast-enhanced CT or contrast-enhanced MRI are both appropriate in evaluating orbital cellulitis, uveitis, or scleritis, with CT often performed first during the initial assessment. Optic neuritis is best assessed with a contrast-enhanced MRI of the orbits and contrast-enhanced MRI of the head, which are often performed in conjunction with one another. Although there are references that report on studies with design limitations, 4 well-designed or good-quality studies provide good evidence. Appropriateness Category Names and Definitions Relative Radiation Level Information Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, a relative radiation level (RRL) indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at Orbits, Vision and Visual Loss

Orbits Vision and Visual Loss. Although CT imaging of the orbits is preferred, CT imaging of the head may be appropriate if an intracranial abnormality is suspected. Precontrast and postcontrast imaging of the orbits is typically not necessary in evaluating these patients as the precontrast images do not add significant diagnostic information in this scenario. Radiography Orbital or skull radiographs are insufficient to detect pathology in patients presenting with proptosis and have primarily been supplanted by CT. Summary of Recommendations Orbital trauma is best assessed with a noncontrast orbit CT and/or noncontrast CT of the head, which are often complementary. Orbital asymmetry, exophthalmos, or enophthalmos can be evaluated with contrast-enhanced orbit CT or contrast-enhanced orbit MRI, which are often complementary. Contrast-enhanced CT or contrast-enhanced MRI are both appropriate in evaluating orbital cellulitis, uveitis, or scleritis, with CT often performed first during the initial assessment. Optic neuritis is best assessed with a contrast-enhanced MRI of the orbits and contrast-enhanced MRI of the head, which are often performed in conjunction with one another. Although there are references that report on studies with design limitations, 4 well-designed or good-quality studies provide good evidence. Appropriateness Category Names and Definitions Relative Radiation Level Information Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, a relative radiation level (RRL) indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at Orbits, Vision and Visual Loss

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