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acrac_3099011_6

Back Pain Child PCAs

MRI Spine MRI of the total spine is sensitive for the imaging evaluation of soft-tissue and bony abnormalities associated with pediatric back pain, including paraspinous soft-tissue pathology, disc disease, marrow edema, and intraspinal masses [8,24-26,32]. Nonneoplastic intraspinal etiologies of back pain such as syrinx and meningoceles are well demonstrated using MRI [34,35]. Two large prospective studies have used MRI in an algorithm for evaluation of pediatric back pain in a total of 348 patients [1,5]. These studies found that MRI had high diagnostic accuracy in identifying and delineating the etiology of pediatric back pain. MRI is especially useful in evaluation of children with positive neurologic findings and should be considered the primary imaging modality in this subset of patients. An imaging algorithm has been proposed that includes only MRI in the imaging evaluation of children with positive neurologic findings [4]. Contrast is helpful in the evaluation of back pain in children when there is clinical or laboratory evidence of infection, inflammation, or tumor [8,13,33]. If contrast is administered, precontrast images are helpful to assess enhancement. There is little use for performing an MRI with contrast only. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques, especially following the administration of contrast. CT Spine Fractures and bone lesions are well delineated on targeted noncontrast CT [7,15]. CT has been found to be complementary to bone scan in evaluation of spondylolysis [4,30]. CT with contrast can be used when infection or tumor is suspected; however, MRI without and with contrast is the modality of choice in the evaluation of these patients. CT with contrast targeted to the area of interest should be considered only when MRI is contraindicated or not feasible. Performing CT both without and with contrast is not usually indicated.

Back Pain Child PCAs. MRI Spine MRI of the total spine is sensitive for the imaging evaluation of soft-tissue and bony abnormalities associated with pediatric back pain, including paraspinous soft-tissue pathology, disc disease, marrow edema, and intraspinal masses [8,24-26,32]. Nonneoplastic intraspinal etiologies of back pain such as syrinx and meningoceles are well demonstrated using MRI [34,35]. Two large prospective studies have used MRI in an algorithm for evaluation of pediatric back pain in a total of 348 patients [1,5]. These studies found that MRI had high diagnostic accuracy in identifying and delineating the etiology of pediatric back pain. MRI is especially useful in evaluation of children with positive neurologic findings and should be considered the primary imaging modality in this subset of patients. An imaging algorithm has been proposed that includes only MRI in the imaging evaluation of children with positive neurologic findings [4]. Contrast is helpful in the evaluation of back pain in children when there is clinical or laboratory evidence of infection, inflammation, or tumor [8,13,33]. If contrast is administered, precontrast images are helpful to assess enhancement. There is little use for performing an MRI with contrast only. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques, especially following the administration of contrast. CT Spine Fractures and bone lesions are well delineated on targeted noncontrast CT [7,15]. CT has been found to be complementary to bone scan in evaluation of spondylolysis [4,30]. CT with contrast can be used when infection or tumor is suspected; however, MRI without and with contrast is the modality of choice in the evaluation of these patients. CT with contrast targeted to the area of interest should be considered only when MRI is contraindicated or not feasible. Performing CT both without and with contrast is not usually indicated.

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acrac_3099011_7

Back Pain Child PCAs

In the circumstance of determining the presence of calcifications, limited images could be obtained through the area of interest. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Tc-99m bone scan may be a useful tool in children with back pain and no specific neurologic findings on physical examination [4]. However, a retrospective study evaluating bone scan as a screening tool found that primary malignancies of the spine were missed in 3 out of 142 patients, although only planar bone scans were obtained in this study [20]. Although bone scan with SPECT can be very sensitive to bone pathology such as spondylolysis [19], potentially significant causes of back pain could be missed using only this modality [8,20]. SPECT/CT is not addressed in this discussion because it is not widely available. Myelography and Postmyelography CT Spine Because of the invasiveness of the procedure, myelography and postmyelography CT of the whole spine are considered in the setting of an abnormal neurologic examination only if MRI is contraindicated or will have significantly limited diagnostic yield because of spinal hardware. Variant 4: Child. Back pain with 1 or more of the following clinical red flags: constant pain, night pain, radicular pain, pain lasting >4 weeks, abnormal neurologic examination. Positive radiographs. MRI Spine MRI is sensitive for the imaging evaluation of soft-tissue and bony abnormalities associated with pediatric back pain, including paraspinous soft-tissue pathology, disc disease, marrow edema, and intraspinal masses that may be suggested on radiographs of the spine [8,24-26,32]. Two large prospective studies have used MRI in an algorithm for evaluation of pediatric back pain in a total of 348 patients [1,5]. These studies found that MRI had high diagnostic accuracy in identifying and delineating the etiology of pediatric back pain; however, if a specific diagnosis was determined using spine radiographs, MRI was not performed.

Back Pain Child PCAs. In the circumstance of determining the presence of calcifications, limited images could be obtained through the area of interest. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Tc-99m bone scan may be a useful tool in children with back pain and no specific neurologic findings on physical examination [4]. However, a retrospective study evaluating bone scan as a screening tool found that primary malignancies of the spine were missed in 3 out of 142 patients, although only planar bone scans were obtained in this study [20]. Although bone scan with SPECT can be very sensitive to bone pathology such as spondylolysis [19], potentially significant causes of back pain could be missed using only this modality [8,20]. SPECT/CT is not addressed in this discussion because it is not widely available. Myelography and Postmyelography CT Spine Because of the invasiveness of the procedure, myelography and postmyelography CT of the whole spine are considered in the setting of an abnormal neurologic examination only if MRI is contraindicated or will have significantly limited diagnostic yield because of spinal hardware. Variant 4: Child. Back pain with 1 or more of the following clinical red flags: constant pain, night pain, radicular pain, pain lasting >4 weeks, abnormal neurologic examination. Positive radiographs. MRI Spine MRI is sensitive for the imaging evaluation of soft-tissue and bony abnormalities associated with pediatric back pain, including paraspinous soft-tissue pathology, disc disease, marrow edema, and intraspinal masses that may be suggested on radiographs of the spine [8,24-26,32]. Two large prospective studies have used MRI in an algorithm for evaluation of pediatric back pain in a total of 348 patients [1,5]. These studies found that MRI had high diagnostic accuracy in identifying and delineating the etiology of pediatric back pain; however, if a specific diagnosis was determined using spine radiographs, MRI was not performed.

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acrac_3099011_8

Back Pain Child PCAs

MRI can confirm and further characterize abnormalities demonstrated on radiographs. MRI is especially useful in evaluation of children with positive neurologic findings. An imaging algorithm has been proposed that includes only MRI in the imaging evaluation of children with positive neurologic findings [4]. If contrast is administered, precontrast images are helpful to assess enhancement. Findings on spine radiographs such as disc-space narrowing, endplate irregularity, bone destruction, or widening of the spinal canal suggest an inflammatory, infectious, or neoplastic process [7,8]. MRI of the total spine without and with contrast is helpful in the evaluation of back pain in children with clinical or imaging evidence of infection, inflammation, or tumor [8,13,33]. There is little use for performing an MRI with contrast only. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques, especially following the administration of contrast. CT Spine Fractures and bone lesions may be suggested on radiographs of the spine. These entities may be better delineated and confirmed on targeted noncontrast CT [7,15]. CT has been found to be complementary to bone scan in evaluation of spondylolysis [4,30]. CT with contrast should be considered only when MRI is contraindicated or not feasible. Performing CT both without and with contrast is not usually indicated. In the circumstance of determining the presence of calcifications, limited noncontrast images could be obtained through the area of interest. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Tc-99m bone scan may be a useful screening tool in children with back pain and no specific neurologic findings on physical examination [4]. Bone scan can confirm the presence of an abnormality suggested on radiographs, and because of the whole-body technique it has the ability to demonstrate additional osseous abnormalities (multifocality) as regions of increased radiotracer uptake [31,36]

Back Pain Child PCAs. MRI can confirm and further characterize abnormalities demonstrated on radiographs. MRI is especially useful in evaluation of children with positive neurologic findings. An imaging algorithm has been proposed that includes only MRI in the imaging evaluation of children with positive neurologic findings [4]. If contrast is administered, precontrast images are helpful to assess enhancement. Findings on spine radiographs such as disc-space narrowing, endplate irregularity, bone destruction, or widening of the spinal canal suggest an inflammatory, infectious, or neoplastic process [7,8]. MRI of the total spine without and with contrast is helpful in the evaluation of back pain in children with clinical or imaging evidence of infection, inflammation, or tumor [8,13,33]. There is little use for performing an MRI with contrast only. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques, especially following the administration of contrast. CT Spine Fractures and bone lesions may be suggested on radiographs of the spine. These entities may be better delineated and confirmed on targeted noncontrast CT [7,15]. CT has been found to be complementary to bone scan in evaluation of spondylolysis [4,30]. CT with contrast should be considered only when MRI is contraindicated or not feasible. Performing CT both without and with contrast is not usually indicated. In the circumstance of determining the presence of calcifications, limited noncontrast images could be obtained through the area of interest. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine Tc-99m bone scan may be a useful screening tool in children with back pain and no specific neurologic findings on physical examination [4]. Bone scan can confirm the presence of an abnormality suggested on radiographs, and because of the whole-body technique it has the ability to demonstrate additional osseous abnormalities (multifocality) as regions of increased radiotracer uptake [31,36]

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acrac_3099011_9

Back Pain Child PCAs

Myelography and Postmyelography CT Spine Because of the invasiveness of the procedure, myelography and postmyelography CT of the total spine are considered in the setting of an abnormal neurologic examination only if MRI is contraindicated or will have significantly limited diagnostic yield because of spinal hardware. Variant 5: Child. Chronic back pain associated with overuse. Mechanical back pain. Radiographs The most common etiology for overuse-related chronic back pain in children is spondylolysis. Radiography of the symptomatic region of the spine is a useful screening tool for spondylolysis, with a sensitivity of 77.6% for anterior-posterior and lateral radiographs [6]. The combination of negative radiographs and a negative clinical examination was reported to have an 0.81 negative predictive value [21]. Additional views did not significantly increase sensitivity [6,9]. Other reports have suggested a lower sensitivity for diagnosing spondylolysis using radiographs as compared to MRI [24]. Other etiologies for chronic back pain, such as apophyseal ring fractures and Scheuermann disease, may be suggested with radiographs alone [31]. MRI Spine MRI can show edema in the region of the pars interarticularis or adjacent pedicle in spondylolysis with negative radiographs and CT. MRI is especially useful in detection of active spondylolysis and has been positively associated with clinical symptomatology [23,24]. Resolution of signal abnormalities suggests a response to therapy and potential prevention of progression to fracture [22,37]. It remains uncertain whether MRI or bone scan with SPECT is preferred in the evaluation of suspected spondylolysis [38]. Abnormalities on MRI such as apophyseal injuries, spondylolysis, and disc disease have been shown to be associated with back pain in the pediatric athlete [39].

Back Pain Child PCAs. Myelography and Postmyelography CT Spine Because of the invasiveness of the procedure, myelography and postmyelography CT of the total spine are considered in the setting of an abnormal neurologic examination only if MRI is contraindicated or will have significantly limited diagnostic yield because of spinal hardware. Variant 5: Child. Chronic back pain associated with overuse. Mechanical back pain. Radiographs The most common etiology for overuse-related chronic back pain in children is spondylolysis. Radiography of the symptomatic region of the spine is a useful screening tool for spondylolysis, with a sensitivity of 77.6% for anterior-posterior and lateral radiographs [6]. The combination of negative radiographs and a negative clinical examination was reported to have an 0.81 negative predictive value [21]. Additional views did not significantly increase sensitivity [6,9]. Other reports have suggested a lower sensitivity for diagnosing spondylolysis using radiographs as compared to MRI [24]. Other etiologies for chronic back pain, such as apophyseal ring fractures and Scheuermann disease, may be suggested with radiographs alone [31]. MRI Spine MRI can show edema in the region of the pars interarticularis or adjacent pedicle in spondylolysis with negative radiographs and CT. MRI is especially useful in detection of active spondylolysis and has been positively associated with clinical symptomatology [23,24]. Resolution of signal abnormalities suggests a response to therapy and potential prevention of progression to fracture [22,37]. It remains uncertain whether MRI or bone scan with SPECT is preferred in the evaluation of suspected spondylolysis [38]. Abnormalities on MRI such as apophyseal injuries, spondylolysis, and disc disease have been shown to be associated with back pain in the pediatric athlete [39].

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acrac_3099011_10

Back Pain Child PCAs

MRI can evaluate radiculopathy elicited by both spondylolytic and nonspondylolytic causes and may demonstrate additional etiologies, including apophyseal fractures, intraspinous ligamentous injury, discogenic injury, Scheuermann disease, and compartment syndromes [8,31,40]. If contrast is administered, precontrast images are needed to assess enhancement. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques. There is little use for performing an MRI with contrast only. Contrast is not indicated in the evaluation of chronic back pain due to suspected mechanical causes. CT Spine CT is mostly considered an adjunct to other imaging modalities and has a high sensitivity in evaluation of spondylolysis [6]. CT is superior to radiographs in evaluation of spondylolysis, and with radiation dose-reduction techniques, a similar dose can be achieved [41]. CT has been shown to be complementary in the evaluation of pars interarticularis injuries and has the potential to direct further management [30]. Early stress reaction may be missed using CT alone without a bone scan or MRI [23,42]. Ring apophyseal injuries are also well demonstrated on CT [15,31]. CT spine with contrast is not indicated in mechanical back pain. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine There have been studies that have shown that bone scan with SPECT is a sensitive imaging technique for the evaluation of suspected spondylolysis at all ages [6,43,44]. Bone scan has been shown to be more sensitive in comparison to MRI for evaluation of active spondylolysis [19]. However, MRI may be able to detect disc pathology and other processes that can mimic or be associated with spondylolysis [32,40]. In chronic spondylolysis with wide separation and smooth margins, the bone scan may be negative [30]. On the other hand, bone scan can demonstrate increased uptake due to a stress reaction while CT reveals no abnormality [42].

Back Pain Child PCAs. MRI can evaluate radiculopathy elicited by both spondylolytic and nonspondylolytic causes and may demonstrate additional etiologies, including apophyseal fractures, intraspinous ligamentous injury, discogenic injury, Scheuermann disease, and compartment syndromes [8,31,40]. If contrast is administered, precontrast images are needed to assess enhancement. MRI of the spine in the clinical setting of back pain should always be performed with fat-saturated imaging techniques. There is little use for performing an MRI with contrast only. Contrast is not indicated in the evaluation of chronic back pain due to suspected mechanical causes. CT Spine CT is mostly considered an adjunct to other imaging modalities and has a high sensitivity in evaluation of spondylolysis [6]. CT is superior to radiographs in evaluation of spondylolysis, and with radiation dose-reduction techniques, a similar dose can be achieved [41]. CT has been shown to be complementary in the evaluation of pars interarticularis injuries and has the potential to direct further management [30]. Early stress reaction may be missed using CT alone without a bone scan or MRI [23,42]. Ring apophyseal injuries are also well demonstrated on CT [15,31]. CT spine with contrast is not indicated in mechanical back pain. Bone Scan Whole Body with SPECT or SPECT/CT Complete Spine There have been studies that have shown that bone scan with SPECT is a sensitive imaging technique for the evaluation of suspected spondylolysis at all ages [6,43,44]. Bone scan has been shown to be more sensitive in comparison to MRI for evaluation of active spondylolysis [19]. However, MRI may be able to detect disc pathology and other processes that can mimic or be associated with spondylolysis [32,40]. In chronic spondylolysis with wide separation and smooth margins, the bone scan may be negative [30]. On the other hand, bone scan can demonstrate increased uptake due to a stress reaction while CT reveals no abnormality [42].

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acrac_3099011_11

Back Pain Child PCAs

Because of the whole-body technique, bone scan can demonstrate additional osseous abnormalities as regions of increased radiotracer uptake [31,36]. Myelography and Postmyelography CT Spine This examination is not indicated in the evaluation of chronic back pain due to suspected mechanical causes and normal neurologic examination. Variant 6: Child. Back pain associated with suspected inflammation, infection, or malignancy. Radiographs Radiography of the area of clinical interest can be suggestive of inflammatory, infectious, or malignant conditions affecting the spine; however, the modality is insensitive and can easily miss subtle findings [27,28]. Discogenic infections occur in the pediatric population and manifest as mild disc-space narrowing on radiographs [7]. Lytic or sclerotic primary and metastatic tumors may be identified along with evidence of bony destruction, periosteal reaction, or a soft-tissue mass. Subtle pedicular erosion with widening of the interpedicular distance or enlargement of the neural foramina may be secondary findings due to an intraspinal tumor [8]. MRI Spine If inflammation, infection, or malignancy is suspected, MRI without and with contrast of the total spine or region of interest is indicated. A noncontrast examination may be indicated in the presence of renal dysfunction. MRI is generally accepted as the primary imaging modality for the detection and evaluation of intra- and paraspinal masses [27,28]. The ability to localize the mass in relation to adjacent neural structures is a significant advantage over other imaging modalities [8]. Infectious spondyloarthropathies also are best imaged using MRI because of its ability to evaluate for epidural extension of disease and cord compromise [8,13,29]. MRI may also be able to differentiate tuberculous from nontuberculous spondylitis [14]. Additionally, inflammatory arthropathies are well evaluated with MRI [33]. If contrast is administered, precontrast images are needed to assess enhancement.

Back Pain Child PCAs. Because of the whole-body technique, bone scan can demonstrate additional osseous abnormalities as regions of increased radiotracer uptake [31,36]. Myelography and Postmyelography CT Spine This examination is not indicated in the evaluation of chronic back pain due to suspected mechanical causes and normal neurologic examination. Variant 6: Child. Back pain associated with suspected inflammation, infection, or malignancy. Radiographs Radiography of the area of clinical interest can be suggestive of inflammatory, infectious, or malignant conditions affecting the spine; however, the modality is insensitive and can easily miss subtle findings [27,28]. Discogenic infections occur in the pediatric population and manifest as mild disc-space narrowing on radiographs [7]. Lytic or sclerotic primary and metastatic tumors may be identified along with evidence of bony destruction, periosteal reaction, or a soft-tissue mass. Subtle pedicular erosion with widening of the interpedicular distance or enlargement of the neural foramina may be secondary findings due to an intraspinal tumor [8]. MRI Spine If inflammation, infection, or malignancy is suspected, MRI without and with contrast of the total spine or region of interest is indicated. A noncontrast examination may be indicated in the presence of renal dysfunction. MRI is generally accepted as the primary imaging modality for the detection and evaluation of intra- and paraspinal masses [27,28]. The ability to localize the mass in relation to adjacent neural structures is a significant advantage over other imaging modalities [8]. Infectious spondyloarthropathies also are best imaged using MRI because of its ability to evaluate for epidural extension of disease and cord compromise [8,13,29]. MRI may also be able to differentiate tuberculous from nontuberculous spondylitis [14]. Additionally, inflammatory arthropathies are well evaluated with MRI [33]. If contrast is administered, precontrast images are needed to assess enhancement.

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acrac_3149012_0

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Introduction/Background Cerebrovascular diseases encompass a range of varied clinical presentations and disease processes. This document focuses on clinical scenarios related to stroke and intraparenchymal hemorrhage (IPH), stroke-like conditions such as venous sinus thrombosis and arterial vascular dissection, and known vascular stroke-related risk factors such as cervical bruit and carotid stenosis. The clinical variants included in this document describe imaging management early in clinical presentation with acute or recent onset of symptoms, as well as ongoing imaging during management of known stroke and stroke-related conditions in the subacute and chronic phases. The subset of cerebrovascular diseases and presentations are broad and varied; therefore, the introduction and background of each variant will be discussed individually. Special Imaging Considerations In many stroke-related clinical scenarios, both parenchymal and vascular imaging procedures are commonly used, particularly in the initial imaging of acute clinical presentations. Noncontrast head CT can be performed rapidly, either alone or included in the performance of CT angiography (CTA) of the head. For the purposes of this document, both procedures are discussed separately for each variant, highlighting the individual usefulness of both the noncontrast examination and contrast-enhanced vascular imaging phase. CTA of the head and neck are often acquired together, using a single contrast bolus for optimal arterial vascular opacification. Although the diagnostic usefulness and/or acuity of intracranial and extracranial vascular assessment may differ within a particular clinical context, the benefit of combined neck and head vascular imaging may have added clinical benefit in circumstances in which transcatheter arterial intervention is a potential consideration.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Introduction/Background Cerebrovascular diseases encompass a range of varied clinical presentations and disease processes. This document focuses on clinical scenarios related to stroke and intraparenchymal hemorrhage (IPH), stroke-like conditions such as venous sinus thrombosis and arterial vascular dissection, and known vascular stroke-related risk factors such as cervical bruit and carotid stenosis. The clinical variants included in this document describe imaging management early in clinical presentation with acute or recent onset of symptoms, as well as ongoing imaging during management of known stroke and stroke-related conditions in the subacute and chronic phases. The subset of cerebrovascular diseases and presentations are broad and varied; therefore, the introduction and background of each variant will be discussed individually. Special Imaging Considerations In many stroke-related clinical scenarios, both parenchymal and vascular imaging procedures are commonly used, particularly in the initial imaging of acute clinical presentations. Noncontrast head CT can be performed rapidly, either alone or included in the performance of CT angiography (CTA) of the head. For the purposes of this document, both procedures are discussed separately for each variant, highlighting the individual usefulness of both the noncontrast examination and contrast-enhanced vascular imaging phase. CTA of the head and neck are often acquired together, using a single contrast bolus for optimal arterial vascular opacification. Although the diagnostic usefulness and/or acuity of intracranial and extracranial vascular assessment may differ within a particular clinical context, the benefit of combined neck and head vascular imaging may have added clinical benefit in circumstances in which transcatheter arterial intervention is a potential consideration.

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acrac_3149012_1

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI perfusion imaging is most commonly performed using intravenous (IV) contrast; however, newer scanners may also have the ability to perform noncontrast perfusion imaging without IV contrast using arterial spin-labeled (ASL) techniques. Future Appropriateness Criteria documents may consider this technique as it achieves greater adoption in routine clinical practice. aUniversity of California San Diego, San Diego, California. bPanel Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. cPanel Vice-Chair, Uniformed Services University, Bethesda, Maryland. dUniversity of Virginia Health System, Charlottesville, Virginia. eUniversity of Washington, Seattle, Washington and University of British Columbia, Vancouver, British Columbia, Canada. fYale University School of Medicine, New Haven, Connecticut; Committee on Emergency Radiology-GSER. gBarrow Neurological Institute, Phoenix, Arizona; Neurosurgery expert. hMayo Clinic, Rochester, Minnesota; Commission on Nuclear Medicine and Molecular Imaging. iWeill Cornell Medical College, New York, New York. jUniversity of Chicago, Chicago, Illinois. kWashington State University, Spokane, Washington; American College of Physicians. lSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians. mAlbany ENT & Allergy Services, PC, Albany, New York; American Academy of Otolaryngology-Head and Neck Surgery. nAlbert Einstein College of Medicine Montefiore Medical Center, Bronx, New York, Primary care physician. oStanford University School of Medicine, Stanford, California. pUniformed Services University of the Health Sciences, Bethesda, Maryland, Naval Medical Center Portsmouth, Portsmouth, Virginia. qUniversity of Colorado School of Medicine, Aurora, Colorado. rUniversity of Cincinnati Medical Center, Cincinnati, Ohio. sSpecialty Chair, Montefiore Medical Center, Bronx, New York.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI perfusion imaging is most commonly performed using intravenous (IV) contrast; however, newer scanners may also have the ability to perform noncontrast perfusion imaging without IV contrast using arterial spin-labeled (ASL) techniques. Future Appropriateness Criteria documents may consider this technique as it achieves greater adoption in routine clinical practice. aUniversity of California San Diego, San Diego, California. bPanel Chair, Atlanta VA Health Care System and Emory University, Atlanta, Georgia. cPanel Vice-Chair, Uniformed Services University, Bethesda, Maryland. dUniversity of Virginia Health System, Charlottesville, Virginia. eUniversity of Washington, Seattle, Washington and University of British Columbia, Vancouver, British Columbia, Canada. fYale University School of Medicine, New Haven, Connecticut; Committee on Emergency Radiology-GSER. gBarrow Neurological Institute, Phoenix, Arizona; Neurosurgery expert. hMayo Clinic, Rochester, Minnesota; Commission on Nuclear Medicine and Molecular Imaging. iWeill Cornell Medical College, New York, New York. jUniversity of Chicago, Chicago, Illinois. kWashington State University, Spokane, Washington; American College of Physicians. lSentara Norfolk General Hospital/Eastern Virginia Medical School, Norfolk, Virginia; American College of Emergency Physicians. mAlbany ENT & Allergy Services, PC, Albany, New York; American Academy of Otolaryngology-Head and Neck Surgery. nAlbert Einstein College of Medicine Montefiore Medical Center, Bronx, New York, Primary care physician. oStanford University School of Medicine, Stanford, California. pUniformed Services University of the Health Sciences, Bethesda, Maryland, Naval Medical Center Portsmouth, Portsmouth, Virginia. qUniversity of Colorado School of Medicine, Aurora, Colorado. rUniversity of Cincinnati Medical Center, Cincinnati, Ohio. sSpecialty Chair, Montefiore Medical Center, Bronx, New York.

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acrac_3149012_2

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

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] OR Discussion of Procedures by Variant Variant 1: Adult. Clinical transient ischemic attack (TIA). Symptoms resolved. Initial imaging. Transient ischemic attacks (TIA) are self-limited focal neurologic deficits resulting from a temporary interruption in blood supply to the brain, with no permanent clinical deficit or demonstrated infarct on subsequent imaging. In the United States, the incidence of TIA is approximately 1.2 per 1,000 [7]. The traditional time-based definition of TIA set the maximum duration at 24 hours. A newer imaging-based definition restricts the term TIA to those without neuroimaging evidence of tissue damage. Practically, those with and without tissue damage are considered together for diagnosis and management proposes [8,9]. Although symptoms may resolve within a short period of time, typically <1 hour, the risk for subsequent stroke is high: 8.8% at 7 days and 11.6% at 90 days [10]. In the setting of symptomatic carotid disease, the 90-day risk of ipsilateral stroke is 20.1% [11]. Given the high risk for stroke following TIA, expeditious initial imaging is important. There is a direct correlation between the risk of stroke following a carotid territory TIA or minor stroke and degree of carotid stenosis, and this drives the decision for carotid endarterectomy (CEA) or stenting [12,13]. Therefore, evaluation of patients with clinical carotid TIA or minor stroke requires rapid vascular imaging of the cervical carotid arteries [12,13] in addition to brain parenchymal imaging.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. 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] OR Discussion of Procedures by Variant Variant 1: Adult. Clinical transient ischemic attack (TIA). Symptoms resolved. Initial imaging. Transient ischemic attacks (TIA) are self-limited focal neurologic deficits resulting from a temporary interruption in blood supply to the brain, with no permanent clinical deficit or demonstrated infarct on subsequent imaging. In the United States, the incidence of TIA is approximately 1.2 per 1,000 [7]. The traditional time-based definition of TIA set the maximum duration at 24 hours. A newer imaging-based definition restricts the term TIA to those without neuroimaging evidence of tissue damage. Practically, those with and without tissue damage are considered together for diagnosis and management proposes [8,9]. Although symptoms may resolve within a short period of time, typically <1 hour, the risk for subsequent stroke is high: 8.8% at 7 days and 11.6% at 90 days [10]. In the setting of symptomatic carotid disease, the 90-day risk of ipsilateral stroke is 20.1% [11]. Given the high risk for stroke following TIA, expeditious initial imaging is important. There is a direct correlation between the risk of stroke following a carotid territory TIA or minor stroke and degree of carotid stenosis, and this drives the decision for carotid endarterectomy (CEA) or stenting [12,13]. Therefore, evaluation of patients with clinical carotid TIA or minor stroke requires rapid vascular imaging of the cervical carotid arteries [12,13] in addition to brain parenchymal imaging.

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Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Arteriography Cervicocerebral Although the spatial resolution of catheter-directed cerebral angiography is higher than any noninvasive technique, cerebral angiography is not preferred as an initial test due to the invasive nature and the diversity of etiologies for TIA. Cerebral angiography may be indicated later in the diagnostic pathway as a secondary examination in the workup of TIA, depending on the suspected underlying etiology and potential indications for endovascular therapy (EVT). CT Head Perfusion With IV Contrast CT perfusion (CTP) can identify abnormalities in the setting of TIA in up to one-third of cases. The detection of an underlying perfusion abnormality may be helpful for risk stratification [14-16]. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. Therefore, CTP is not typically used for the initial assessment of TIA. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of TIA. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of TIA. CT Head Without IV Contrast Noncontrast CT of the head is useful in the initial evaluation of TIA to exclude alternative etiologies and to evaluate for early ischemic changes. Many other lesions may mimic the symptoms of a TIA including intracranial hemorrhage (ICH), infection, and intracranial masses [14,19,20]. Most importantly, ICH must be excluded because it is a contraindication to administration of tissue thrombolytic agents, anticoagulants, and antiplatelet agents used to treat and prevent both TIA and stroke [13].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Although the spatial resolution of catheter-directed cerebral angiography is higher than any noninvasive technique, cerebral angiography is not preferred as an initial test due to the invasive nature and the diversity of etiologies for TIA. Cerebral angiography may be indicated later in the diagnostic pathway as a secondary examination in the workup of TIA, depending on the suspected underlying etiology and potential indications for endovascular therapy (EVT). CT Head Perfusion With IV Contrast CT perfusion (CTP) can identify abnormalities in the setting of TIA in up to one-third of cases. The detection of an underlying perfusion abnormality may be helpful for risk stratification [14-16]. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. Therefore, CTP is not typically used for the initial assessment of TIA. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of TIA. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of TIA. CT Head Without IV Contrast Noncontrast CT of the head is useful in the initial evaluation of TIA to exclude alternative etiologies and to evaluate for early ischemic changes. Many other lesions may mimic the symptoms of a TIA including intracranial hemorrhage (ICH), infection, and intracranial masses [14,19,20]. Most importantly, ICH must be excluded because it is a contraindication to administration of tissue thrombolytic agents, anticoagulants, and antiplatelet agents used to treat and prevent both TIA and stroke [13].

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acrac_3149012_4

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Moreover, the extent of ischemic changes seen on noncontrast CT, regardless of chronicity, is correlated with the risk of subsequent strokes [21]. Cerebrovascular Diseases-Stroke CTA Head With IV Contrast CTA of the head is a rapid means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis and other intracranial steno-occlusive diseases, which may be useful in the secondary workup and triage of patients presenting with TIA. The identification of atherosclerotic intracranial vascular lesions in the setting of TIA may be useful in determining the most appropriate treatment options, although this is controversial [22,23]. CTA Neck With IV Contrast CTA of the neck is a rapid means of evaluating the extracranial vasculature and is useful in the initial workup and triage of patients presenting with carotid territory TIA. Current American Heart Association (AHA) guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting within 48 hours of onset [12]. Heavy calcifications or calcified plaque on both sides of the lumen can lead to overestimation of the stenosis [24]. CTV Head With IV Contrast There is no relevant literature to support the use of CT venography (CTV) head in the evaluation of TIA in the absence of suspicion for cerebral venous thrombosis (CVT). Please see Variant 7 for further details. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MR angiography (MRA) of the head in the evaluation of TIA. MRA Head Without IV Contrast MRA of the head is an alternative means of evaluating intracranial steno-occlusive disease and may be useful in the initial workup and triage of patients presenting with TIA.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Moreover, the extent of ischemic changes seen on noncontrast CT, regardless of chronicity, is correlated with the risk of subsequent strokes [21]. Cerebrovascular Diseases-Stroke CTA Head With IV Contrast CTA of the head is a rapid means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis and other intracranial steno-occlusive diseases, which may be useful in the secondary workup and triage of patients presenting with TIA. The identification of atherosclerotic intracranial vascular lesions in the setting of TIA may be useful in determining the most appropriate treatment options, although this is controversial [22,23]. CTA Neck With IV Contrast CTA of the neck is a rapid means of evaluating the extracranial vasculature and is useful in the initial workup and triage of patients presenting with carotid territory TIA. Current American Heart Association (AHA) guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting within 48 hours of onset [12]. Heavy calcifications or calcified plaque on both sides of the lumen can lead to overestimation of the stenosis [24]. CTV Head With IV Contrast There is no relevant literature to support the use of CT venography (CTV) head in the evaluation of TIA in the absence of suspicion for cerebral venous thrombosis (CVT). Please see Variant 7 for further details. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MR angiography (MRA) of the head in the evaluation of TIA. MRA Head Without IV Contrast MRA of the head is an alternative means of evaluating intracranial steno-occlusive disease and may be useful in the initial workup and triage of patients presenting with TIA.

3149012

acrac_3149012_5

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Owing to the relatively rapid and noninvasive nature of the examination obviating the need for IV contrast, MRA may be preferable to CTA in patients with renal impairment, x-ray contrast allergy, or repeat presentations. Typically, noncontrast time-of-flight (TOF) MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [25]. MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial vascular disease in the initial workup and triage of patients presenting with TIA. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast- enhanced MRA, particularly in cases of high-grade stenosis [26]. Typically, noncontrast TOF MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [27]. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial vascular disease in the initial workup and triage of patients presenting with TIA. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast- enhanced MRA, particularly in cases of high-grade stenosis [26]. Typically, noncontrast TOF MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [27].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Owing to the relatively rapid and noninvasive nature of the examination obviating the need for IV contrast, MRA may be preferable to CTA in patients with renal impairment, x-ray contrast allergy, or repeat presentations. Typically, noncontrast time-of-flight (TOF) MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [25]. MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial vascular disease in the initial workup and triage of patients presenting with TIA. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast- enhanced MRA, particularly in cases of high-grade stenosis [26]. Typically, noncontrast TOF MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [27]. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial vascular disease in the initial workup and triage of patients presenting with TIA. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast- enhanced MRA, particularly in cases of high-grade stenosis [26]. Typically, noncontrast TOF MRA technique is sufficiently sensitive to screen for culprit intracranial lesions in the setting of suspected TIA [27].

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acrac_3149012_6

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional abnormalities not identified on initial vascular imaging or diffusion-weighted imaging (DWI) in some patients presenting with TIA. Either technique may be useful in the secondary workup and triage of patients presenting with TIA depending on the suspected underlying etiology, particularly if no abnormalities are identified on direct vascular or parenchymal imaging studies [28-30]. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. MRI Head Without and With IV Contrast Noncontrast MRI head is typically sufficient for the routine assessment of uncomplicated TIA. Conditions rarely mimicking TIA include tumors and cerebral convexity subarachnoid hemorrhage due to amyloid angiopathy. MRI Cerebrovascular Diseases-Stroke without and with IV contrast may be helpful in the secondary workup of patients presenting with transient focal neurological symptoms [34]. MRI Head Without IV Contrast Owing to the relatively rapid noninvasive nature of MRI and the high sensitivity of DWI for ischemic change, MRI is the most sensitive test for acute infarct. MRI of the head may be useful in the initial or secondary evaluation of TIA to evaluate for ischemic changes on DWI or for other alternative etiologies [34,35]. MRI is particularly useful prognostically as an initial test in the setting of complete resolution of associated symptoms before presentation or shortly after presentation [29]. Additionally, MRI may be useful as an initial test on repeat clinical presentation [36].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional abnormalities not identified on initial vascular imaging or diffusion-weighted imaging (DWI) in some patients presenting with TIA. Either technique may be useful in the secondary workup and triage of patients presenting with TIA depending on the suspected underlying etiology, particularly if no abnormalities are identified on direct vascular or parenchymal imaging studies [28-30]. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. MRI Head Without and With IV Contrast Noncontrast MRI head is typically sufficient for the routine assessment of uncomplicated TIA. Conditions rarely mimicking TIA include tumors and cerebral convexity subarachnoid hemorrhage due to amyloid angiopathy. MRI Cerebrovascular Diseases-Stroke without and with IV contrast may be helpful in the secondary workup of patients presenting with transient focal neurological symptoms [34]. MRI Head Without IV Contrast Owing to the relatively rapid noninvasive nature of MRI and the high sensitivity of DWI for ischemic change, MRI is the most sensitive test for acute infarct. MRI of the head may be useful in the initial or secondary evaluation of TIA to evaluate for ischemic changes on DWI or for other alternative etiologies [34,35]. MRI is particularly useful prognostically as an initial test in the setting of complete resolution of associated symptoms before presentation or shortly after presentation [29]. Additionally, MRI may be useful as an initial test on repeat clinical presentation [36].

3149012

acrac_3149012_7

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRV Head Without and With IV Contrast There is no relevant literature to support the use of MR venography (MRV) of the head in the evaluation of TIA in the absence of suspicion of CVT, which can rarely present as a TIA [37]. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of TIA in the absence of suspicion of CVT, which can rarely present as a TIA [37]. US Duplex Doppler Carotid Artery Ultrasound (US) duplex carotid Doppler is a useful test in the initial evaluation of the extracranial vasculature in the workup of TIA. Carotid Doppler US is noninvasive and is accurate in evaluating the degree of carotid stenosis [38]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting within 48 hours of onset [12]. US Duplex Doppler Transcranial Transcranial Doppler can be used for the detection of microembolic events and in the detection of intracranial vascular pathology in the secondary workup of TIA. However, this is not typically used as an initial imaging test in the setting of TIA. Arteriography Cervicocerebral Cerebral angiography has the highest spatial and temporal resolution of any vascular imaging study. Due to the invasive nature of catheter-directed angiography, other modalities are typically preferred in the initial workup for stroke. However, in the setting of highly suspected LVO with no need for perfusion imaging or MRI to determine eligibility for EVT, initial catheter angiography after noncontrast CT may be the preferable vascular imaging study due to the ability to rapidly convert a diagnostic catheter angiogram to EVT [53,54].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MR venography (MRV) of the head in the evaluation of TIA in the absence of suspicion of CVT, which can rarely present as a TIA [37]. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of TIA in the absence of suspicion of CVT, which can rarely present as a TIA [37]. US Duplex Doppler Carotid Artery Ultrasound (US) duplex carotid Doppler is a useful test in the initial evaluation of the extracranial vasculature in the workup of TIA. Carotid Doppler US is noninvasive and is accurate in evaluating the degree of carotid stenosis [38]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting within 48 hours of onset [12]. US Duplex Doppler Transcranial Transcranial Doppler can be used for the detection of microembolic events and in the detection of intracranial vascular pathology in the secondary workup of TIA. However, this is not typically used as an initial imaging test in the setting of TIA. Arteriography Cervicocerebral Cerebral angiography has the highest spatial and temporal resolution of any vascular imaging study. Due to the invasive nature of catheter-directed angiography, other modalities are typically preferred in the initial workup for stroke. However, in the setting of highly suspected LVO with no need for perfusion imaging or MRI to determine eligibility for EVT, initial catheter angiography after noncontrast CT may be the preferable vascular imaging study due to the ability to rapidly convert a diagnostic catheter angiogram to EVT [53,54].

3149012

acrac_3149012_8

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

More specifically, patients presenting with suspicious signs on noncontrast CT such as hyperdense middle cerebral artery sign with a clear etiology for the LVO such as new onset atrial fibrillation may benefit from proceeding directly to angiography, although prospective data are limited in this regard [55]. Cerebrovascular Diseases-Stroke CT Head Perfusion With IV Contrast Within the initial 6-hour window of presentation of an acute stroke, CTP of the head is usually not necessary as an initial examination; conversely, delay, created by obtaining and analyzing CTP in the setting of a known LVO patient who is a clear EVT candidate, may be harmful [13,56]. In contrast, determining eligibility for EVT for anterior circulation strokes due to LVO confirmed on CTA presenting in the extended window of 6 to 24 hours may require or be determined by CTP or MR perfusion imaging in some cases [46,57]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of ischemic stroke. CTA Head With IV Contrast CTA of the head is the most rapid means of assessment of the intracranial vasculature for LVO in the setting of stroke. CTA of the head has a high sensitivity and specificity for the detection of intracranial LVO [60]. Stroke, possibly due to LVO, is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. More specifically, patients presenting with suspicious signs on noncontrast CT such as hyperdense middle cerebral artery sign with a clear etiology for the LVO such as new onset atrial fibrillation may benefit from proceeding directly to angiography, although prospective data are limited in this regard [55]. Cerebrovascular Diseases-Stroke CT Head Perfusion With IV Contrast Within the initial 6-hour window of presentation of an acute stroke, CTP of the head is usually not necessary as an initial examination; conversely, delay, created by obtaining and analyzing CTP in the setting of a known LVO patient who is a clear EVT candidate, may be harmful [13,56]. In contrast, determining eligibility for EVT for anterior circulation strokes due to LVO confirmed on CTA presenting in the extended window of 6 to 24 hours may require or be determined by CTP or MR perfusion imaging in some cases [46,57]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of ischemic stroke. CTA Head With IV Contrast CTA of the head is the most rapid means of assessment of the intracranial vasculature for LVO in the setting of stroke. CTA of the head has a high sensitivity and specificity for the detection of intracranial LVO [60]. Stroke, possibly due to LVO, is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration.

3149012

acrac_3149012_9

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

The use of CTA of the head for the initial test in the detection of LVO is supported by multiple RCTs and is the preferred means of LVO detection due to the time-sensitive nature of stroke care [44,46,48,49,57]. Moreover, in the absence of an LVO, other etiologies such as atherosclerosis, vasculitis, reversible cerebral vasoconstrictive syndrome, or other etiologies may be suggested by CTA of the head. CTA Neck With IV Contrast CTA of the neck is the most rapid means of assessment of the extracranial vasculature in the setting of stroke. CTA of the neck can be rapidly acquired together with CTA of the head, can further elucidate the etiology of the stroke, and may be useful for endovascular surgical planning for EVT in LVO [13]. Specifically, the degree of vascular tortuosity is directly correlated with the time from groin puncture to recanalization and must be factored into the decision-making process both with regards to indications and surgical approach, including the choice of access using radial artery or direct carotid puncture approach [61]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of suspected ischemic stroke in the absence of suspicion for CVT. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of suspected ischemic stroke. MRA Head Without IV Contrast Although sensitive and specific in the detection of LVO, TOF MRA of the head may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. The use of CTA of the head for the initial test in the detection of LVO is supported by multiple RCTs and is the preferred means of LVO detection due to the time-sensitive nature of stroke care [44,46,48,49,57]. Moreover, in the absence of an LVO, other etiologies such as atherosclerosis, vasculitis, reversible cerebral vasoconstrictive syndrome, or other etiologies may be suggested by CTA of the head. CTA Neck With IV Contrast CTA of the neck is the most rapid means of assessment of the extracranial vasculature in the setting of stroke. CTA of the neck can be rapidly acquired together with CTA of the head, can further elucidate the etiology of the stroke, and may be useful for endovascular surgical planning for EVT in LVO [13]. Specifically, the degree of vascular tortuosity is directly correlated with the time from groin puncture to recanalization and must be factored into the decision-making process both with regards to indications and surgical approach, including the choice of access using radial artery or direct carotid puncture approach [61]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of suspected ischemic stroke in the absence of suspicion for CVT. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of suspected ischemic stroke. MRA Head Without IV Contrast Although sensitive and specific in the detection of LVO, TOF MRA of the head may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56].

3149012

acrac_3149012_10

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast Cerebrovascular Diseases-Stroke allergy, TOF MRA can be used to identify arterial occlusions without putting the patient at risk and inform subsequent therapeutic decisions [52]. MRA Neck Without and With IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. MRA Neck Without IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast Cerebrovascular Diseases-Stroke allergy, TOF MRA can be used to identify arterial occlusions without putting the patient at risk and inform subsequent therapeutic decisions [52]. MRA Neck Without and With IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. MRA Neck Without IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52].

3149012

acrac_3149012_11

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI Head Perfusion With IV Contrast MRI head perfusion is sensitive and specific in the detection of reversible ischemia. MRI head perfusion may delay EVT in the setting of stroke due to LVO, which detracts from the usefulness of this study in the acute phase due to the potential harm of delayed treatment [39]. Although major RCTs showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on MRI perfusion or CTP [46,57], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62]. MRI Head Without IV Contrast Although sensitive and specific in the detection of the extent of irreversible ischemia, MRI head may delay EVT in the setting of stroke due to anterior circulation LVO, which detracts from the usefulness of this study due to the potential harm of delayed treatment [39,46,56]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. Similarly, the 2 positive RCTs for EVT in basilar occlusion used pc-ASPECTS from either DWI-MRI or noncontrast CT for eligibility. The rapidity of CT makes it preferable in this situation as well [48,49]. However, for some wake-up strokes and for some anterior circulation strokes with large infarcts, DWI-MRI and fluid-attenuated inversion recovery (FLAIR) sequences are necessary to determine eligibility for thrombolytics and EVT, respectively [40,47].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast MRI head perfusion is sensitive and specific in the detection of reversible ischemia. MRI head perfusion may delay EVT in the setting of stroke due to LVO, which detracts from the usefulness of this study in the acute phase due to the potential harm of delayed treatment [39]. Although major RCTs showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on MRI perfusion or CTP [46,57], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62]. MRI Head Without IV Contrast Although sensitive and specific in the detection of the extent of irreversible ischemia, MRI head may delay EVT in the setting of stroke due to anterior circulation LVO, which detracts from the usefulness of this study due to the potential harm of delayed treatment [39,46,56]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. Similarly, the 2 positive RCTs for EVT in basilar occlusion used pc-ASPECTS from either DWI-MRI or noncontrast CT for eligibility. The rapidity of CT makes it preferable in this situation as well [48,49]. However, for some wake-up strokes and for some anterior circulation strokes with large infarcts, DWI-MRI and fluid-attenuated inversion recovery (FLAIR) sequences are necessary to determine eligibility for thrombolytics and EVT, respectively [40,47].

3149012

acrac_3149012_12

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

In patients with renal insufficiency or x-ray contrast allergy, the combination TOF MRA to identify arterial occlusions and DWI-MRI head without IV contrast can identify patients eligible for EVT 6 to 24 hours without putting the patient at risk and inform subsequent therapeutic decisions [46,47,52]. MRI is a reasonable complementary examination used in the initial workup of a focal neurological deficit if LVO is excluded by CTA, when there are confounding imaging and clinical variables. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT. Cerebrovascular Diseases-Stroke US Duplex Doppler Carotid Artery Although sensitive and specific in the detection of extracranial vascular disease, duplex carotid Doppler does not provide the information necessary to determine eligibility for thrombolytics or thrombolysis or EVT. US duplex carotid Doppler, which is noninvasive and is accurate in evaluating the degree of carotid stenosis, is a useful test for the evaluation of the extracranial vasculature to determine eligibility for CEA or stenting if this information has not already been obtained from other vascular imaging [63,64]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. In patients with renal insufficiency or x-ray contrast allergy, the combination TOF MRA to identify arterial occlusions and DWI-MRI head without IV contrast can identify patients eligible for EVT 6 to 24 hours without putting the patient at risk and inform subsequent therapeutic decisions [46,47,52]. MRI is a reasonable complementary examination used in the initial workup of a focal neurological deficit if LVO is excluded by CTA, when there are confounding imaging and clinical variables. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT. Cerebrovascular Diseases-Stroke US Duplex Doppler Carotid Artery Although sensitive and specific in the detection of extracranial vascular disease, duplex carotid Doppler does not provide the information necessary to determine eligibility for thrombolytics or thrombolysis or EVT. US duplex carotid Doppler, which is noninvasive and is accurate in evaluating the degree of carotid stenosis, is a useful test for the evaluation of the extracranial vasculature to determine eligibility for CEA or stenting if this information has not already been obtained from other vascular imaging [63,64]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology.

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acrac_3149012_13

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

However, this is typically not an initial imaging test in the setting of stroke due to the poor anatomical delineation of US and potential consequences of delayed treatment in the setting of LVO [39]. Variant 3: Adult. Recent ischemic infarct; less than 24 hours. Initial imaging. This variant is focused on new clinical presentation of stroke in the acute phase, <24 hours from onset of symptoms, but beyond hyperacute clinical presentation. Because stroke due to LVO is a significant source of death and disability, rapid stroke diagnosis and triage remain essential, particularly in the setting of possible LVO [39]. Recent studies have shown the benefit of extending the thrombolytic window up to 9 hours using perfusion imaging [40- 43]. However, a number of positive RCTs have demonstrated the benefit of EVT in the treatment of stroke due to LVO up to 24 hours underscoring the urgency of LVO detection and resulting in a paradigmatic shift in the urgency of obtaining vascular imaging [44-49]. In the context of nonemergent suspected stroke, parenchymal and vascular imaging are still needed, although the determination of eligibility for EVT in cases of delayed or unknown presentation may require additional MRI sequences or perfusion imaging with CT or MRI depending on the time since last known normal and the severity of the neurological deficit [52]. In the absence of LVO, the workup of a new stroke focuses on treatment of complications, rehabilitation, and secondary prevention. Arteriography Cervicocerebral Cerebral angiography has the highest spatial and temporal resolution of any vascular imaging study. Due to the invasive nature of catheter-directed angiography, other modalities are typically preferred in the initial workup for stroke.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. However, this is typically not an initial imaging test in the setting of stroke due to the poor anatomical delineation of US and potential consequences of delayed treatment in the setting of LVO [39]. Variant 3: Adult. Recent ischemic infarct; less than 24 hours. Initial imaging. This variant is focused on new clinical presentation of stroke in the acute phase, <24 hours from onset of symptoms, but beyond hyperacute clinical presentation. Because stroke due to LVO is a significant source of death and disability, rapid stroke diagnosis and triage remain essential, particularly in the setting of possible LVO [39]. Recent studies have shown the benefit of extending the thrombolytic window up to 9 hours using perfusion imaging [40- 43]. However, a number of positive RCTs have demonstrated the benefit of EVT in the treatment of stroke due to LVO up to 24 hours underscoring the urgency of LVO detection and resulting in a paradigmatic shift in the urgency of obtaining vascular imaging [44-49]. In the context of nonemergent suspected stroke, parenchymal and vascular imaging are still needed, although the determination of eligibility for EVT in cases of delayed or unknown presentation may require additional MRI sequences or perfusion imaging with CT or MRI depending on the time since last known normal and the severity of the neurological deficit [52]. In the absence of LVO, the workup of a new stroke focuses on treatment of complications, rehabilitation, and secondary prevention. Arteriography Cervicocerebral Cerebral angiography has the highest spatial and temporal resolution of any vascular imaging study. Due to the invasive nature of catheter-directed angiography, other modalities are typically preferred in the initial workup for stroke.

3149012

acrac_3149012_14

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

However, in the setting of highly suspected LVO with no need for perfusion imaging or MRI to determine eligibility for EVT, initial catheter angiography after noncontrast CT may be the preferable vascular imaging study due to the ability to rapidly convert a diagnostic catheter angiogram to EVT [53,54]. More specifically, patients presenting with suspicious signs on noncontrast CT such as hyperdense middle cerebral artery sign with a clear etiology for the LVO such as new onset atrial fibrillation may benefit from proceeding directly to angiography, although prospective data are limited in this regard [55]. CT Head Perfusion With IV Contrast Beyond the early 6-hour time window, determining eligibility for EVT for anterior circulation strokes due to LVO confirmed on CTA in the extended window of 6 to 24 hours may require or be determined by CTP or MR perfusion imaging in some cases [46,57]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head with and without contrast in the evaluation of ischemic stroke. Cerebrovascular Diseases-Stroke irreversible tissue damage. Because many RCTs of acute ischemic stroke treatments used the ASPECTS or pc- ASPECTS based on noncontrast CT or DWI-MRI to exclude subjects with large, completed infarcts, an initial noncontrast CT or DWI-MRI is essential for making therapeutic decisions [44,46-49,57-59]. CTA Head With IV Contrast CTA of the head is the most rapid means of assessment of the intracranial vasculature for LVO in the setting of stroke.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. However, in the setting of highly suspected LVO with no need for perfusion imaging or MRI to determine eligibility for EVT, initial catheter angiography after noncontrast CT may be the preferable vascular imaging study due to the ability to rapidly convert a diagnostic catheter angiogram to EVT [53,54]. More specifically, patients presenting with suspicious signs on noncontrast CT such as hyperdense middle cerebral artery sign with a clear etiology for the LVO such as new onset atrial fibrillation may benefit from proceeding directly to angiography, although prospective data are limited in this regard [55]. CT Head Perfusion With IV Contrast Beyond the early 6-hour time window, determining eligibility for EVT for anterior circulation strokes due to LVO confirmed on CTA in the extended window of 6 to 24 hours may require or be determined by CTP or MR perfusion imaging in some cases [46,57]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head with and without contrast in the evaluation of ischemic stroke. Cerebrovascular Diseases-Stroke irreversible tissue damage. Because many RCTs of acute ischemic stroke treatments used the ASPECTS or pc- ASPECTS based on noncontrast CT or DWI-MRI to exclude subjects with large, completed infarcts, an initial noncontrast CT or DWI-MRI is essential for making therapeutic decisions [44,46-49,57-59]. CTA Head With IV Contrast CTA of the head is the most rapid means of assessment of the intracranial vasculature for LVO in the setting of stroke.

3149012

acrac_3149012_15

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CTA of the head has a high sensitivity and specificity for the detection of intracranial LVO [60]. Acute stroke possibly due to LVO is a true medical emergency requiring rapid diagnosis, and the use of CTA of the head for the initial test in the detection of LVO is supported by multiple RCTs and is the preferred means of LVO detection due to the time-sensitive nature of stroke care [44,46,48,49,57]. Moreover, in the absence of an LVO, other etiologies such as atherosclerosis, vasculitis, reversible cerebral vasoconstrictive syndrome, or other etiologies may be suggested by CTA of the head. CTA Neck With IV Contrast CTA of the neck is the most rapid means of assessment of the extracranial vasculature in the setting of stroke. CTA of the neck can be rapidly acquired together with CTA of the head, can further elucidate the etiology of the stroke, and may be useful for endovascular surgical planning for EVT in LVO [13]. Specifically, the degree of vascular tortuosity is directly correlated with the time from groin puncture to recanalization and must be factored into the decision-making process both with regards to indications and surgical approach, including the choice of access using radial artery or direct carotid puncture approach [61]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of suspected ischemic stroke in the absence of suspicion for CVT. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of suspected ischemic stroke. MRA Head Without IV Contrast TOF MRA of the head is sensitive and specific in the detection of LVO and characterization of intracranial atherosclerosis.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA of the head has a high sensitivity and specificity for the detection of intracranial LVO [60]. Acute stroke possibly due to LVO is a true medical emergency requiring rapid diagnosis, and the use of CTA of the head for the initial test in the detection of LVO is supported by multiple RCTs and is the preferred means of LVO detection due to the time-sensitive nature of stroke care [44,46,48,49,57]. Moreover, in the absence of an LVO, other etiologies such as atherosclerosis, vasculitis, reversible cerebral vasoconstrictive syndrome, or other etiologies may be suggested by CTA of the head. CTA Neck With IV Contrast CTA of the neck is the most rapid means of assessment of the extracranial vasculature in the setting of stroke. CTA of the neck can be rapidly acquired together with CTA of the head, can further elucidate the etiology of the stroke, and may be useful for endovascular surgical planning for EVT in LVO [13]. Specifically, the degree of vascular tortuosity is directly correlated with the time from groin puncture to recanalization and must be factored into the decision-making process both with regards to indications and surgical approach, including the choice of access using radial artery or direct carotid puncture approach [61]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of suspected ischemic stroke in the absence of suspicion for CVT. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of suspected ischemic stroke. MRA Head Without IV Contrast TOF MRA of the head is sensitive and specific in the detection of LVO and characterization of intracranial atherosclerosis.

3149012

acrac_3149012_16

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

In the acute setting, CTA is generally acquired more rapidly than MRI and delay due to MRI should be avoided, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to identify arterial occlusions without putting the patient at risk and inform subsequent therapeutic decisions [52]. MRA Neck Without and With IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. MRA Neck Without IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. In the acute setting, CTA is generally acquired more rapidly than MRI and delay due to MRI should be avoided, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to identify arterial occlusions without putting the patient at risk and inform subsequent therapeutic decisions [52]. MRA Neck Without and With IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12]. MRA Neck Without IV Contrast Although sensitive and specific in the detection of extracranial vascular disease and delineation of anatomy, MRA of the neck may delay EVT in the setting of stroke due to LVO, which possibly detracts from the usefulness of this procedure due to the potential harm of delayed treatment, unless MRA is readily available in the hyperacute setting [39,56]. Stroke due to LVO is a true medical emergency in which the rapidity of diagnosis afforded by CTA is a strongly relevant clinical consideration.

3149012

acrac_3149012_17

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Cerebrovascular Diseases-Stroke MRI Head Perfusion With IV Contrast MRI head perfusion is sensitive and specific in the detection of reversible ischemia. MRI head perfusion may delay EVT in the setting of stroke due to LVO, which detracts from the usefulness of this study in the acute phase due to the potential harm of delayed treatment [39]. Although major RCTs showing a benefit of EVT 6 to 24 hours after onset permitted eligibility based on MRI perfusion or CTP [46,57], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62]. MRI Head Without IV Contrast Although sensitive and specific in the detection of the extent of irreversible ischemia, MRI head may delay EVT in the setting of stroke due to anterior circulation LVO, which detracts from the usefulness of this study due to the potential harm of delayed treatment [39,46,56]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings Similarly, the 2 positive RCTs for EVT in basilar occlusion used pc-ASPECTS from either DWI-MRI or noncontrast CT for eligibility. The rapidity of CT makes it preferable in this situation as well [48,49].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. In patients with renal insufficiency or x-ray contrast allergy, TOF MRA can be used to delineate arterial anatomy without putting the patient at risk and inform subsequent therapeutic decisions [52]. Cerebrovascular Diseases-Stroke MRI Head Perfusion With IV Contrast MRI head perfusion is sensitive and specific in the detection of reversible ischemia. MRI head perfusion may delay EVT in the setting of stroke due to LVO, which detracts from the usefulness of this study in the acute phase due to the potential harm of delayed treatment [39]. Although major RCTs showing a benefit of EVT 6 to 24 hours after onset permitted eligibility based on MRI perfusion or CTP [46,57], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62]. MRI Head Without IV Contrast Although sensitive and specific in the detection of the extent of irreversible ischemia, MRI head may delay EVT in the setting of stroke due to anterior circulation LVO, which detracts from the usefulness of this study due to the potential harm of delayed treatment [39,46,56]. Although a major RCT showing benefit of EVT 6 to 24 hours after onset permitted eligibility based on DWI-MRI or CTP [46], the rapidity of diagnosis afforded by CTP is a strongly relevant clinical consideration in this situation in most settings Similarly, the 2 positive RCTs for EVT in basilar occlusion used pc-ASPECTS from either DWI-MRI or noncontrast CT for eligibility. The rapidity of CT makes it preferable in this situation as well [48,49].

3149012

acrac_3149012_18

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

However, for some wake-up strokes and for some anterior circulation strokes with large infarcts, DWI-MRI and FLAIR sequences are necessary to determine eligibility for thrombolytics and EVT, respectively [40,47]. In patients with renal insufficiency or x-ray contrast allergy, the combination TOF MRA to identify arterial occlusions and DWI-MRI head without IV contrast can identify patients eligible for EVT 6 to 24 hours without putting the patient at risk and inform subsequent therapeutic decisions [46,47,52]. MRI is a reasonable complementary examination used in the initial workup of a focal neurological deficit if LVO is excluded by CTA, when there are confounding imaging and clinical variables. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT. US Duplex Doppler Carotid Artery Although sensitive and specific in the detection of extracranial vascular disease, duplex carotid Doppler does not provide the information necessary to determine eligibility for thrombolytics or EVT. US duplex carotid Doppler, which is noninvasive and is accurate in evaluating the degree of carotid stenosis, is a useful test for the evaluation of the extracranial vasculature to determine eligibility for CEA or stenting if this information has not already been obtained from other vascular imaging. [63,64]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. However, for some wake-up strokes and for some anterior circulation strokes with large infarcts, DWI-MRI and FLAIR sequences are necessary to determine eligibility for thrombolytics and EVT, respectively [40,47]. In patients with renal insufficiency or x-ray contrast allergy, the combination TOF MRA to identify arterial occlusions and DWI-MRI head without IV contrast can identify patients eligible for EVT 6 to 24 hours without putting the patient at risk and inform subsequent therapeutic decisions [46,47,52]. MRI is a reasonable complementary examination used in the initial workup of a focal neurological deficit if LVO is excluded by CTA, when there are confounding imaging and clinical variables. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of suspected ischemic stroke in the absence of specific suspicion for CVT. US Duplex Doppler Carotid Artery Although sensitive and specific in the detection of extracranial vascular disease, duplex carotid Doppler does not provide the information necessary to determine eligibility for thrombolytics or EVT. US duplex carotid Doppler, which is noninvasive and is accurate in evaluating the degree of carotid stenosis, is a useful test for the evaluation of the extracranial vasculature to determine eligibility for CEA or stenting if this information has not already been obtained from other vascular imaging. [63,64]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with TIA or minor stroke who are candidates for CEA or stenting, within 48 hours of onset [12].

3149012

acrac_3149012_19

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke due to the poor anatomical delineation of US and potential consequences of delayed treatment in the setting of LVO [39]. Variant 4: Adult. Recent ischemic infarct; greater than 24 hours. Initial imaging. This variant addresses cases of clinically suspected recent ischemic infarct, although beyond the established and extended stroke windows, that is, >24 hours after symptom onset. Whereas some observational studies suggest benefit [65], no large RCTs have demonstrated the benefit of EVT for LVO strokes after the 24 hour mark. Given the lack of supporting evidence for the usefulness for EVT beyond 24 hours, the urgency of exclusion of stroke due to LVO is largely abated and the workup of a new stroke becomes less urgent. At this stage, imaging is more focused on stroke follow-up and treatment of complications, rehabilitation planning, and secondary prevention [13]. Cerebrovascular Diseases-Stroke Arteriography Cervicocerebral Cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study and may detect underlying etiologies in patients presenting with stroke in a delayed fashion beyond 24 hours, which may not be detectable by other modalities, and can potentially help guide management. The usefulness of revascularization for intracranial LVO beyond 24 hours has not been demonstrated by RCT, which reduces the urgency of diagnosis [65]. Moreover, the urgency of diagnosis of many other stroke etiologies detected only by arteriography in the setting of delayed presentation is less well defined beyond 24 hours. Cerebral angiography is typically reserved for diagnoses not excluded by less invasive modalities and even then is of uncertain specificity and sensitivity [66].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke due to the poor anatomical delineation of US and potential consequences of delayed treatment in the setting of LVO [39]. Variant 4: Adult. Recent ischemic infarct; greater than 24 hours. Initial imaging. This variant addresses cases of clinically suspected recent ischemic infarct, although beyond the established and extended stroke windows, that is, >24 hours after symptom onset. Whereas some observational studies suggest benefit [65], no large RCTs have demonstrated the benefit of EVT for LVO strokes after the 24 hour mark. Given the lack of supporting evidence for the usefulness for EVT beyond 24 hours, the urgency of exclusion of stroke due to LVO is largely abated and the workup of a new stroke becomes less urgent. At this stage, imaging is more focused on stroke follow-up and treatment of complications, rehabilitation planning, and secondary prevention [13]. Cerebrovascular Diseases-Stroke Arteriography Cervicocerebral Cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study and may detect underlying etiologies in patients presenting with stroke in a delayed fashion beyond 24 hours, which may not be detectable by other modalities, and can potentially help guide management. The usefulness of revascularization for intracranial LVO beyond 24 hours has not been demonstrated by RCT, which reduces the urgency of diagnosis [65]. Moreover, the urgency of diagnosis of many other stroke etiologies detected only by arteriography in the setting of delayed presentation is less well defined beyond 24 hours. Cerebral angiography is typically reserved for diagnoses not excluded by less invasive modalities and even then is of uncertain specificity and sensitivity [66].

3149012

acrac_3149012_20

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CT Head Perfusion With IV Contrast CT head perfusion imaging may detect an underlying lesion not identified by other imaging modalities in some cases of late presenting with strokes and may identify additional at-risk regions of the brain. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. CTP may be a reasonable examination in the secondary workup of late presenting strokes, but it is not generally a first-line test in this clinical context. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke; in fact, contrast may obscure early complications such as hemorrhage. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of ischemic stroke; in fact, contrast may obscure early complications such as hemorrhage. CT Head Without IV Contrast Noncontrast CT of the head is essential in the initial evaluation of delayed presenting strokes to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation. Moreover, noncontrast CT is more sensitive for the evaluation of early ischemic changes in late presenting strokes than in the hyperacute setting [67]. Dual-energy CT may play a role in the setting of prior contrast administration for other studies or for prior EVT in evaluating for underlying hemorrhage [68].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast CT head perfusion imaging may detect an underlying lesion not identified by other imaging modalities in some cases of late presenting with strokes and may identify additional at-risk regions of the brain. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. CTP may be a reasonable examination in the secondary workup of late presenting strokes, but it is not generally a first-line test in this clinical context. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of ischemic stroke; in fact, contrast may obscure early complications such as hemorrhage. CT Head Without and With IV Contrast There is no relevant literature to support the use of CT of the head without and with IV contrast in the evaluation of ischemic stroke; in fact, contrast may obscure early complications such as hemorrhage. CT Head Without IV Contrast Noncontrast CT of the head is essential in the initial evaluation of delayed presenting strokes to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation. Moreover, noncontrast CT is more sensitive for the evaluation of early ischemic changes in late presenting strokes than in the hyperacute setting [67]. Dual-energy CT may play a role in the setting of prior contrast administration for other studies or for prior EVT in evaluating for underlying hemorrhage [68].

3149012

acrac_3149012_21

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CTA Head With IV Contrast CTA of the head is a rapid and highly sensitive means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis, LVO, and other intracranial steno-occlusive diseases, which may be useful in the management of late presenting strokes, although this is controversial [22,23,69]. However, the urgency of diagnosis of the underlying etiology is less well defined. Moreover, similar information can be obtained from MRA of the head, when there is no need for rapid triage and vascular diagnosis. CTA Neck With IV Contrast CTA of the neck is a rapid and highly sensitive means of evaluating the extracranial vasculature underlying carotid stenosis and other steno-occlusive disease of the cervical vasculature, which is useful in the management of late presenting strokes. However, the urgency of diagnosis of the underlying etiology is less well defined. Moreover, similar information can be obtained from MRA of the head, when there is no need for rapid triage and vascular diagnosis. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of ischemic stroke in the absence of suspicion for CVT. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of ischemic stroke.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Head With IV Contrast CTA of the head is a rapid and highly sensitive means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis, LVO, and other intracranial steno-occlusive diseases, which may be useful in the management of late presenting strokes, although this is controversial [22,23,69]. However, the urgency of diagnosis of the underlying etiology is less well defined. Moreover, similar information can be obtained from MRA of the head, when there is no need for rapid triage and vascular diagnosis. CTA Neck With IV Contrast CTA of the neck is a rapid and highly sensitive means of evaluating the extracranial vasculature underlying carotid stenosis and other steno-occlusive disease of the cervical vasculature, which is useful in the management of late presenting strokes. However, the urgency of diagnosis of the underlying etiology is less well defined. Moreover, similar information can be obtained from MRA of the head, when there is no need for rapid triage and vascular diagnosis. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV head in the evaluation of ischemic stroke in the absence of suspicion for CVT. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of ischemic stroke.

3149012

acrac_3149012_22

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRA Head Without IV Contrast MRA of the head is a rapid, noninvasive tool, which is useful in the initial workup of late presenting stroke to evaluate for intracranial steno-occlusive disease when there is no indication for urgent EVT, although the clinical value of this information is controversial [22,23,69]. Cerebrovascular Diseases-Stroke MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease. However, MRA of the neck tends to overestimate the degree of carotid stenosis in the absence of contrast administration [70] and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts [71]. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease. However, MRA of the neck tends to overestimate the degree of carotid stenosis in the absence of contrast administration [70] and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts [71]. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional at-risk regions not demonstrated by DWI and aid in identifying the underlying etiology in some patients presenting with stroke beyond the 24-hour period. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. Perfusion imaging is not generally considered a first-line test in this clinical context [72,73]. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without IV Contrast MRA of the head is a rapid, noninvasive tool, which is useful in the initial workup of late presenting stroke to evaluate for intracranial steno-occlusive disease when there is no indication for urgent EVT, although the clinical value of this information is controversial [22,23,69]. Cerebrovascular Diseases-Stroke MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease. However, MRA of the neck tends to overestimate the degree of carotid stenosis in the absence of contrast administration [70] and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts [71]. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease. However, MRA of the neck tends to overestimate the degree of carotid stenosis in the absence of contrast administration [70] and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts [71]. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional at-risk regions not demonstrated by DWI and aid in identifying the underlying etiology in some patients presenting with stroke beyond the 24-hour period. Specific instances arise in patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. Perfusion imaging is not generally considered a first-line test in this clinical context [72,73]. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62].

3149012

acrac_3149012_23

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI Head Without IV Contrast DWI-MRI and T2-weighted sequences are highly sensitive for ischemic changes in the patient with acute ischemic stroke. Although often performed as part of the initial evaluation of late presenting strokes to delineate the extent of completed ischemic infarct, evaluate potential underlying etiology, and identify any complications, the value of the information provided by MRI over initial CT for improving patient outcome is unclear, as are the circumstances in which it is useful [74-79]. Current AHA guidelines only specify MRI in 2 circumstances: evaluation for wake- up strokes and evaluation for patent foramen ovale closure [12,13]. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head without and with IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head without IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT. US Duplex Doppler Carotid Artery Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. US duplex carotid Doppler is useful for assessing the degree of carotid stenosis in anterior circulation infarcts due to the noninvasive nature of the examination, the high degree of accuracy, and the absence of time pressure of EVT candidacy associated with delayed presenting strokes [38,80]. Carotid Doppler is a highly accurate tool for evaluating for and assessing the degree of carotid stenosis in anterior circulation infarcts, which CTA may overestimate, particularly in the setting of significant carotid calcification [24,38].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast DWI-MRI and T2-weighted sequences are highly sensitive for ischemic changes in the patient with acute ischemic stroke. Although often performed as part of the initial evaluation of late presenting strokes to delineate the extent of completed ischemic infarct, evaluate potential underlying etiology, and identify any complications, the value of the information provided by MRI over initial CT for improving patient outcome is unclear, as are the circumstances in which it is useful [74-79]. Current AHA guidelines only specify MRI in 2 circumstances: evaluation for wake- up strokes and evaluation for patent foramen ovale closure [12,13]. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head without and with IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head without IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT. US Duplex Doppler Carotid Artery Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. US duplex carotid Doppler is useful for assessing the degree of carotid stenosis in anterior circulation infarcts due to the noninvasive nature of the examination, the high degree of accuracy, and the absence of time pressure of EVT candidacy associated with delayed presenting strokes [38,80]. Carotid Doppler is a highly accurate tool for evaluating for and assessing the degree of carotid stenosis in anterior circulation infarcts, which CTA may overestimate, particularly in the setting of significant carotid calcification [24,38].

3149012

acrac_3149012_24

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke. Variant 5: Adult. Prior ischemic infarct. Surveillance imaging. After the initial ischemic injury is defined, identifying the presence of any complications such as hemorrhagic conversion or associated mass effect become the focus of evaluation of recent ischemic infarcts, which are both less emergent than identifying EVT candidates. The extent of the initial ischemic injury plays a key role in defining the risk for delayed complications and the need for and expected duration of ongoing surveillance. Ongoing ischemia or hemorrhagic complication may impact the timeline for initiation of anticoagulant and/or antiplatelet therapy. For large hemispheric or cerebellar infarcts, prolonged observation or early craniectomy may be indicated, which would Cerebrovascular Diseases-Stroke argue for delaying any preventative measures and/or treatments that pose a risk of operative bleeding [13]. If not previously performed during initial triage, cardiocerebrovascular assessment has a secondary but important clinical role. Arteriography Cervicocerebral Cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study and may detect early progression of known steno-occlusive intracranial or cervical atherosclerotic disease before detection on other studies. As such, cerebral angiography may be useful in follow-up imaging in select ischemic strokes, particularly those in which the findings on noninvasive imaging are indeterminate. Cerebral angiography is typically reserved for diagnoses not excluded by less invasive modalities and even then is of uncertain specificity and sensitivity [66].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke. Variant 5: Adult. Prior ischemic infarct. Surveillance imaging. After the initial ischemic injury is defined, identifying the presence of any complications such as hemorrhagic conversion or associated mass effect become the focus of evaluation of recent ischemic infarcts, which are both less emergent than identifying EVT candidates. The extent of the initial ischemic injury plays a key role in defining the risk for delayed complications and the need for and expected duration of ongoing surveillance. Ongoing ischemia or hemorrhagic complication may impact the timeline for initiation of anticoagulant and/or antiplatelet therapy. For large hemispheric or cerebellar infarcts, prolonged observation or early craniectomy may be indicated, which would Cerebrovascular Diseases-Stroke argue for delaying any preventative measures and/or treatments that pose a risk of operative bleeding [13]. If not previously performed during initial triage, cardiocerebrovascular assessment has a secondary but important clinical role. Arteriography Cervicocerebral Cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study and may detect early progression of known steno-occlusive intracranial or cervical atherosclerotic disease before detection on other studies. As such, cerebral angiography may be useful in follow-up imaging in select ischemic strokes, particularly those in which the findings on noninvasive imaging are indeterminate. Cerebral angiography is typically reserved for diagnoses not excluded by less invasive modalities and even then is of uncertain specificity and sensitivity [66].

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Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CT Head Perfusion CT head perfusion imaging may identify the progression of known underlying intracranial or extracranial atherosclerotic disease, which could predict recurrent or new ischemic events in the future. CTP may be used for surveillance examination in the cases in which known vascular lesions are present. In the absence of a known steno- occlusive lesion, there is no literature to support the use of CTP in surveillance imaging of prior ischemic strokes. In patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. CT Head With IV Contrast There is no role for IV contrast in the CT evaluation of evolving or subacute infarct. In fact, contrast enhancement within previously undocumented subacute infarcts can paradoxically cause confusion with other more aggressive brain lesions or hemorrhagic conversion of prior infarcts. CT Head Without and With IV Contrast There is no role for IV contrast in the CT evaluation of evolving or subacute infarct. In fact, contrast enhancement within previously undocumented subacute infarcts can paradoxically cause confusion with other more aggressive brain lesions or hemorrhagic conversion of prior infarcts. CT Head Without IV Contrast Noncontrast CT of the head can be useful in the early surveillance of ischemic strokes to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation when clinically indicated. Moreover, noncontrast CT is more sensitive for the evaluation of the extent of ischemic changes on follow-up imaging of strokes than in the hyperacute setting [67]. In circumstances in which ongoing surveillance is warranted, CT is usually preferred due to its quick repeatability and ease of comparison to prior examinations.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion CT head perfusion imaging may identify the progression of known underlying intracranial or extracranial atherosclerotic disease, which could predict recurrent or new ischemic events in the future. CTP may be used for surveillance examination in the cases in which known vascular lesions are present. In the absence of a known steno- occlusive lesion, there is no literature to support the use of CTP in surveillance imaging of prior ischemic strokes. In patients with complete extracranial internal carotid artery occlusion in whom CTP can be used to determine its hemodynamic effect [17]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. CT Head With IV Contrast There is no role for IV contrast in the CT evaluation of evolving or subacute infarct. In fact, contrast enhancement within previously undocumented subacute infarcts can paradoxically cause confusion with other more aggressive brain lesions or hemorrhagic conversion of prior infarcts. CT Head Without and With IV Contrast There is no role for IV contrast in the CT evaluation of evolving or subacute infarct. In fact, contrast enhancement within previously undocumented subacute infarcts can paradoxically cause confusion with other more aggressive brain lesions or hemorrhagic conversion of prior infarcts. CT Head Without IV Contrast Noncontrast CT of the head can be useful in the early surveillance of ischemic strokes to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation when clinically indicated. Moreover, noncontrast CT is more sensitive for the evaluation of the extent of ischemic changes on follow-up imaging of strokes than in the hyperacute setting [67]. In circumstances in which ongoing surveillance is warranted, CT is usually preferred due to its quick repeatability and ease of comparison to prior examinations.

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acrac_3149012_26

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Dual-energy CT may play a role in the setting of prior contrast administration for other studies or for prior EVT in evaluating for underlying hemorrhage [68]. CTA Head With IV Contrast CTA of the head is a rapid means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis and steno-occlusive diseases, although the clinical value of this information is controversial [22,23,69]. Identification of the underlying etiology in the absence of progressive symptoms is less time sensitive than with patients undergoing EVT evaluation. Moreover, similar information can be obtained from MRA of the head without the need for rapid triage and vascular diagnosis. CTA of the head may be indicated in unstable patients presenting with uncertainty or concern for progression of prior ischemic infarcts. CTA Neck With IV Contrast CTA of the neck is a rapid means of evaluating the extracranial vasculature underlying carotid stenosis and other steno-occlusive disease of the cervical vasculature, which is useful in the management of late presenting strokes. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. In the absence of bilateral disease, carotid Doppler is more accurate in evaluating the degree of carotid stenosis; CTA typically overestimates stenosis, particularly in the setting of dense carotid calcification [24]. In the setting of cryptogenic stroke, CTA may be helpful to diagnose unsuspected carotid webs or other features of unstable plaque [81,82]. Cerebrovascular Diseases-Stroke CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the evaluation of ischemic stroke in the absence of suspicion for CVT.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Dual-energy CT may play a role in the setting of prior contrast administration for other studies or for prior EVT in evaluating for underlying hemorrhage [68]. CTA Head With IV Contrast CTA of the head is a rapid means of evaluating the intracranial vasculature for underlying intracranial atherosclerosis and steno-occlusive diseases, although the clinical value of this information is controversial [22,23,69]. Identification of the underlying etiology in the absence of progressive symptoms is less time sensitive than with patients undergoing EVT evaluation. Moreover, similar information can be obtained from MRA of the head without the need for rapid triage and vascular diagnosis. CTA of the head may be indicated in unstable patients presenting with uncertainty or concern for progression of prior ischemic infarcts. CTA Neck With IV Contrast CTA of the neck is a rapid means of evaluating the extracranial vasculature underlying carotid stenosis and other steno-occlusive disease of the cervical vasculature, which is useful in the management of late presenting strokes. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. In the absence of bilateral disease, carotid Doppler is more accurate in evaluating the degree of carotid stenosis; CTA typically overestimates stenosis, particularly in the setting of dense carotid calcification [24]. In the setting of cryptogenic stroke, CTA may be helpful to diagnose unsuspected carotid webs or other features of unstable plaque [81,82]. Cerebrovascular Diseases-Stroke CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the evaluation of ischemic stroke in the absence of suspicion for CVT.

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acrac_3149012_27

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of ischemic stroke. MRA Head Without IV Contrast MRA of the head is a useful initial screening tests for intracranial steno-occlusive disease in the setting of late presenting stroke, owing to the lack of indication for emergent EVT in delayed presenting strokes and relatively rapid noninvasive nature of the examination without the need for IV contrast, although the clinical value of this information is controversial [22,23,69]. MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease given the lack of urgency in evaluation of delayed presenting strokes. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis. In the setting of cryptogenic stroke, MRA can be useful to identify unstable plaque or other culprit lesions [83-85]. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease given the lack of urgency in the evaluation of delayed presenting strokes. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts. Contrast- enhanced MRA may more accurately quantify stenosis and identify ostial stenoses. In the setting of cryptogenic stroke, MRA can be useful to identify unstable plaque or other culprit lesions [83-85].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of ischemic stroke. MRA Head Without IV Contrast MRA of the head is a useful initial screening tests for intracranial steno-occlusive disease in the setting of late presenting stroke, owing to the lack of indication for emergent EVT in delayed presenting strokes and relatively rapid noninvasive nature of the examination without the need for IV contrast, although the clinical value of this information is controversial [22,23,69]. MRA Neck Without and With IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease given the lack of urgency in evaluation of delayed presenting strokes. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis. In the setting of cryptogenic stroke, MRA can be useful to identify unstable plaque or other culprit lesions [83-85]. MRA Neck Without IV Contrast MRA of the neck may be useful in screening for extracranial carotid disease given the lack of urgency in the evaluation of delayed presenting strokes. Noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis and is often limited in evaluation of vertebral origin disease due to respiratory motion artifacts. Contrast- enhanced MRA may more accurately quantify stenosis and identify ostial stenoses. In the setting of cryptogenic stroke, MRA can be useful to identify unstable plaque or other culprit lesions [83-85].

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Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional at-risk regions not demonstrated by DWI in some patients presenting with stroke beyond the 24-hour period. In patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. However, this procedure is more useful as a problem-solving tool and is not considered standard as surveillance imaging in the setting of prior infarct. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62]. MRI Head Without IV Contrast MRI of the head may be a useful initial test in evaluation of the extent of completed ischemic infarct in the setting of late presenting strokes owing to the relatively rapid noninvasive nature of the examination, the lack of need for IV contrast, and the high sensitivity of DWI for concurrent acute ischemic change. Although often performed as part of the initial evaluation of late presenting strokes to delineate the extent of completed ischemic infarct, evaluate potential underlying etiology, and identify any complications, the value of the information provided by MRI over initial CT for improving patient outcome is unclear, as are the circumstances in which it is useful [74-79]. Current AHA guidelines only specify MRI in 2 circumstances: evaluation for wake-up strokes and evaluation for patent foramen ovale closure [12,13].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may detect additional at-risk regions not demonstrated by DWI in some patients presenting with stroke beyond the 24-hour period. In patients with complete extracranial internal carotid artery occlusion in whom MR perfusion can be used to determine its hemodynamic effect [31-33]. However, selection of patients with carotid occlusion for revascularization based on hemodynamic compromise does not improve outcome [18]. However, this procedure is more useful as a problem-solving tool and is not considered standard as surveillance imaging in the setting of prior infarct. MRI Head Without and With IV Contrast Rarely, brain tumors or other conditions can mimic ischemic stroke. MRI without and with IV contrast may be helpful in the secondary workup of patients presenting with stroke-like symptoms [62]. MRI Head Without IV Contrast MRI of the head may be a useful initial test in evaluation of the extent of completed ischemic infarct in the setting of late presenting strokes owing to the relatively rapid noninvasive nature of the examination, the lack of need for IV contrast, and the high sensitivity of DWI for concurrent acute ischemic change. Although often performed as part of the initial evaluation of late presenting strokes to delineate the extent of completed ischemic infarct, evaluate potential underlying etiology, and identify any complications, the value of the information provided by MRI over initial CT for improving patient outcome is unclear, as are the circumstances in which it is useful [74-79]. Current AHA guidelines only specify MRI in 2 circumstances: evaluation for wake-up strokes and evaluation for patent foramen ovale closure [12,13].

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acrac_3149012_29

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head without and with IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head without IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT. Cerebrovascular Diseases-Stroke US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very useful screening test in the evaluation of the extracranial vasculature for carotid stenosis in delayed presenting strokes, due to the high degree of accuracy in evaluating the degree of carotid stenosis in the absence of multifocal disease and the absence of time pressure of EVT candidacy associated with delayed presenting strokes [38]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke. Variant 6: Adult. Known intraparenchymal hemorrhage. No history of trauma. Follow-up imaging study. IPH may complicate many cerebrovascular and systemic conditions including hypertension, cerebral amyloid angiopathy, coagulopathy, arteriovenous malformation, dural arteriovenous fistula, CVT, cortical venous thrombosis, aneurysm, certain primary central nervous system neoplasms, cerebral hyperperfusion syndromes in the setting of carotid revascularization, metastatic disease, cavernous malformations, prior ischemic infarct, and Moyamoya disease [86].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head without and with IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head without IV contrast in the evaluation of ischemic stroke in the absence of suspicion for CVT. Cerebrovascular Diseases-Stroke US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very useful screening test in the evaluation of the extracranial vasculature for carotid stenosis in delayed presenting strokes, due to the high degree of accuracy in evaluating the degree of carotid stenosis in the absence of multifocal disease and the absence of time pressure of EVT candidacy associated with delayed presenting strokes [38]. Current AHA guidelines recommend noninvasive imaging of the cervical carotid arteries for patients with minor stroke who are candidates for CEA or stenting, within 24 hours of hospitalization or 48 hours of onset due to the high early risk of recurrent stroke in patients with symptomatic carotid stenosis [12,13]. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in the detection of intracranial vascular pathology. However, this is typically not an initial imaging test in the setting of stroke. Variant 6: Adult. Known intraparenchymal hemorrhage. No history of trauma. Follow-up imaging study. IPH may complicate many cerebrovascular and systemic conditions including hypertension, cerebral amyloid angiopathy, coagulopathy, arteriovenous malformation, dural arteriovenous fistula, CVT, cortical venous thrombosis, aneurysm, certain primary central nervous system neoplasms, cerebral hyperperfusion syndromes in the setting of carotid revascularization, metastatic disease, cavernous malformations, prior ischemic infarct, and Moyamoya disease [86].

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Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Hypertensive hemorrhage is the most common etiology for atraumatic IPH and is often supported by clinical history of hypertension and associated imaging findings of a single deep IPH in the basal ganglia, thalamus, pons, or cerebellum. Cerebral amyloid angiopathy is the second most common cause of IPH. Without pathological conformation, it can be diagnosed with acceptable accuracy based on MRI [87]. Diagnostic evaluation of IPH is directed at determining causes for IPH that may require specific interventions beyond supportive care for the IPH itself. These include arteriovenous malformation, dural arteriovenous fistula, CVT, cortical venous thrombosis, aneurysm, central nervous system neoplasms, cerebral hyperperfusion syndromes in the setting of carotid revascularization, metastatic disease, cavernous malformations, and Moyamoya disease. In cases of typical hypertensive hemorrhage or cerebral amyloid angiopathy, additional imaging may not even be warranted [87,88]. This variant focuses on imaging follow-up of patients previously diagnosed with IPH. Patients with IPH may require advanced monitoring or undergo emergent neurosurgical intervention depending on the degree of associated mass effect, edema, and the rate of expansion associated with the hemorrhage. Many potential etiologies for IPH may require both vascular imaging and advanced parenchymal imaging for full evaluation, if not previously performed during initial imaging triage. Arteriography Cervicocerebral Catheter-directed arteriography is the reference standard for identifying vascular lesions in patients with IPH. However, catheter angiography is an invasive procedure, and noninvasive vascular imaging studies are typically preferable as first-line vascular imaging once hemorrhage is identified. Catheter angiography is useful to further characterize vascular malformations, particularly if suggested by noninvasive testing.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Hypertensive hemorrhage is the most common etiology for atraumatic IPH and is often supported by clinical history of hypertension and associated imaging findings of a single deep IPH in the basal ganglia, thalamus, pons, or cerebellum. Cerebral amyloid angiopathy is the second most common cause of IPH. Without pathological conformation, it can be diagnosed with acceptable accuracy based on MRI [87]. Diagnostic evaluation of IPH is directed at determining causes for IPH that may require specific interventions beyond supportive care for the IPH itself. These include arteriovenous malformation, dural arteriovenous fistula, CVT, cortical venous thrombosis, aneurysm, central nervous system neoplasms, cerebral hyperperfusion syndromes in the setting of carotid revascularization, metastatic disease, cavernous malformations, and Moyamoya disease. In cases of typical hypertensive hemorrhage or cerebral amyloid angiopathy, additional imaging may not even be warranted [87,88]. This variant focuses on imaging follow-up of patients previously diagnosed with IPH. Patients with IPH may require advanced monitoring or undergo emergent neurosurgical intervention depending on the degree of associated mass effect, edema, and the rate of expansion associated with the hemorrhage. Many potential etiologies for IPH may require both vascular imaging and advanced parenchymal imaging for full evaluation, if not previously performed during initial imaging triage. Arteriography Cervicocerebral Catheter-directed arteriography is the reference standard for identifying vascular lesions in patients with IPH. However, catheter angiography is an invasive procedure, and noninvasive vascular imaging studies are typically preferable as first-line vascular imaging once hemorrhage is identified. Catheter angiography is useful to further characterize vascular malformations, particularly if suggested by noninvasive testing.

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Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Although CTA and MRI/MRA have a high sensitivity and specificity compared with catheter arteriography (see below), they may miss important lesions. In one series of 89 patients with IPH not in the typical hypertensive locations who had negative CTA and MRI/MRA, catheter arteriography identified 7 arteriovenous malformations and 3 dural arteriovenous fistulas [89]. In the acute period, catheter arteriography may miss vascular lesions that are detected by repeat arteriography several weeks later [90]. In addition, catheter arteriography is usually performed in patients with pure intraventricular hemorrhage, due to the high prevalence of vascular lesions [88]. Cerebrovascular Diseases-Stroke CT Head With IV Contrast Contrast-enhanced CT is typically not helpful in the setting of typical hypertensive hemorrhage or in serial follow- up, except in cases in which underlying metastatic disease is suspected and MRI is not feasible for a specific patient. CT Head Without and With IV Contrast Contrast-enhanced CT is typically not helpful in the setting of typical hypertensive hemorrhage or in serial follow- up, except in cases in which underlying metastatic disease is suspected and MRI is not feasible for a specific patient. CT Head Without IV Contrast In the setting of IPH, noncontrast CT examinations of the head is essential, both for the initial diagnosis and, if clinically indicated, for follow-up examinations to evaluate for expansion and worsening mass effect. Additional noncontrast CT imaging may not be warranted when the patient is stable. CTA Neck With IV Contrast In the setting of IPH, CTA of the neck is not supported by the literature. CTA of the neck may be useful for treatment planning when endovascular management is expected. CTV Head With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support CTV of the head. However, CTV of the head may be useful to exclude CVT as a potential etiology.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Although CTA and MRI/MRA have a high sensitivity and specificity compared with catheter arteriography (see below), they may miss important lesions. In one series of 89 patients with IPH not in the typical hypertensive locations who had negative CTA and MRI/MRA, catheter arteriography identified 7 arteriovenous malformations and 3 dural arteriovenous fistulas [89]. In the acute period, catheter arteriography may miss vascular lesions that are detected by repeat arteriography several weeks later [90]. In addition, catheter arteriography is usually performed in patients with pure intraventricular hemorrhage, due to the high prevalence of vascular lesions [88]. Cerebrovascular Diseases-Stroke CT Head With IV Contrast Contrast-enhanced CT is typically not helpful in the setting of typical hypertensive hemorrhage or in serial follow- up, except in cases in which underlying metastatic disease is suspected and MRI is not feasible for a specific patient. CT Head Without and With IV Contrast Contrast-enhanced CT is typically not helpful in the setting of typical hypertensive hemorrhage or in serial follow- up, except in cases in which underlying metastatic disease is suspected and MRI is not feasible for a specific patient. CT Head Without IV Contrast In the setting of IPH, noncontrast CT examinations of the head is essential, both for the initial diagnosis and, if clinically indicated, for follow-up examinations to evaluate for expansion and worsening mass effect. Additional noncontrast CT imaging may not be warranted when the patient is stable. CTA Neck With IV Contrast In the setting of IPH, CTA of the neck is not supported by the literature. CTA of the neck may be useful for treatment planning when endovascular management is expected. CTV Head With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support CTV of the head. However, CTV of the head may be useful to exclude CVT as a potential etiology.

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acrac_3149012_32

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Imaging features on noncontrast CT suggesting venous infarction with hemorrhage may include atypical distributions not matching arterial vascular territories, infarcts with cortical sparing, typical parasagittal or temporoparietal location, or dural venous/cortical venous hyperdensity suggestive of thrombus. For further discussion of the evaluation of CVT, see Variant 7. MRA Head Without and With IV Contrast There is a limited role for MRA of the head with IV contrast except when dynamic imaging is performed, such as in the setting of known arteriovenous malformations. MRA Head Without IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRA of the head. However, MRA of the head may be useful in advanced workups to exclude underlying vascular malformations if the etiology is uncertain. In a 2014 review, MRA had a reported sensitivity and specificity exceeding 90% compared with catheter arteriography for detecting intracranial vascular malformations [93]. More recently, MRA was shown to be useful in identifying macrovascular causes such of IPH as aneurysms or arteriovenous malformations [95]. MRA Neck Without and With IV Contrast In the setting of IPH, MRA of the neck is not supported by the literature. MRA of the neck may be useful for treatment planning when endovascular management is expected. MRA Neck Without IV Contrast In the setting of IPH, MRA of the neck is not supported by the literature. MRA of the neck may be useful for treatment planning when endovascular management is expected. MRI Head Perfusion With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRI perfusion of the head as a follow-up imaging study.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Imaging features on noncontrast CT suggesting venous infarction with hemorrhage may include atypical distributions not matching arterial vascular territories, infarcts with cortical sparing, typical parasagittal or temporoparietal location, or dural venous/cortical venous hyperdensity suggestive of thrombus. For further discussion of the evaluation of CVT, see Variant 7. MRA Head Without and With IV Contrast There is a limited role for MRA of the head with IV contrast except when dynamic imaging is performed, such as in the setting of known arteriovenous malformations. MRA Head Without IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRA of the head. However, MRA of the head may be useful in advanced workups to exclude underlying vascular malformations if the etiology is uncertain. In a 2014 review, MRA had a reported sensitivity and specificity exceeding 90% compared with catheter arteriography for detecting intracranial vascular malformations [93]. More recently, MRA was shown to be useful in identifying macrovascular causes such of IPH as aneurysms or arteriovenous malformations [95]. MRA Neck Without and With IV Contrast In the setting of IPH, MRA of the neck is not supported by the literature. MRA of the neck may be useful for treatment planning when endovascular management is expected. MRA Neck Without IV Contrast In the setting of IPH, MRA of the neck is not supported by the literature. MRA of the neck may be useful for treatment planning when endovascular management is expected. MRI Head Perfusion With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRI perfusion of the head as a follow-up imaging study.

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Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI perfusion of the head may be useful in evaluating for secondary etiologies such as hyperperfusion associated with carotid revascularization, tumors, prior ischemic strokes, arteriovenous shunt lesions, or other cerebrovascular malformations, particularly if clinically suspected or suggested on prior imaging. Recommendations for imaging in the setting of suspected aneurysm, arteriovenous shunt lesion, or MRI Head Without and With IV Contrast MRI of the head is a useful test for evaluating alternative etiologies in patients <55 years of age who do not have typical hypertensive hemorrhage [96]. MRI without and with IV contrast can be useful in evaluating for cerebral amyloid angiopathy, tumor, vasculitis, dural venous sinus thrombosis, vascular shunt lesions, and in further characterizing other etiologies seen on noncontrast imaging [97,98]. MRI Head Without IV Contrast MRI of the head is a useful test for evaluating alternative etiologies when the diagnosis of hypertensive hemorrhage is in doubt. Noncontrast MRI can exclude stroke and may suggest certain etiologies including cerebral amyloid angiopathy and cavernous malformations [97,98]. MRV Head Without and With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRV of the head. However, MRV of the head may be useful to exclude CVT as an etiology, particularly if suggested by features of hemorrhage on initial CT imaging or the diagnosis is in doubt based on contrast-enhanced MRI. MRV Head Without IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRV of the head. However, MRV of the head may be useful to exclude CVT as an etiology, particularly if suggested by features of hemorrhage on initial CT imaging or the diagnosis is in doubt based on contrast-enhanced MRI.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI perfusion of the head may be useful in evaluating for secondary etiologies such as hyperperfusion associated with carotid revascularization, tumors, prior ischemic strokes, arteriovenous shunt lesions, or other cerebrovascular malformations, particularly if clinically suspected or suggested on prior imaging. Recommendations for imaging in the setting of suspected aneurysm, arteriovenous shunt lesion, or MRI Head Without and With IV Contrast MRI of the head is a useful test for evaluating alternative etiologies in patients <55 years of age who do not have typical hypertensive hemorrhage [96]. MRI without and with IV contrast can be useful in evaluating for cerebral amyloid angiopathy, tumor, vasculitis, dural venous sinus thrombosis, vascular shunt lesions, and in further characterizing other etiologies seen on noncontrast imaging [97,98]. MRI Head Without IV Contrast MRI of the head is a useful test for evaluating alternative etiologies when the diagnosis of hypertensive hemorrhage is in doubt. Noncontrast MRI can exclude stroke and may suggest certain etiologies including cerebral amyloid angiopathy and cavernous malformations [97,98]. MRV Head Without and With IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRV of the head. However, MRV of the head may be useful to exclude CVT as an etiology, particularly if suggested by features of hemorrhage on initial CT imaging or the diagnosis is in doubt based on contrast-enhanced MRI. MRV Head Without IV Contrast In the setting of typical hypertensive hemorrhage, there is no relevant literature to support MRV of the head. However, MRV of the head may be useful to exclude CVT as an etiology, particularly if suggested by features of hemorrhage on initial CT imaging or the diagnosis is in doubt based on contrast-enhanced MRI.

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acrac_3149012_34

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

US Duplex Doppler Carotid Artery In the setting of IPH, US duplex Doppler carotid of the neck is not supported by the literature. US Duplex Doppler Transcranial In the setting of suspected hypertensive hemorrhage, there is no relevant literature to support transcranial Doppler. Variant 7: Adult. Suspected venous sinus thrombosis. Initial imaging. CVT is an uncommon cause for stroke, accounting for approximately 1% to 2% of all strokes [99]. The patients often have hypercoagulable risk factors (cancer, recent oral contraceptive use, and pregnancy) and may present with headaches, seizures, or decreased level of consciousness due to either venous ischemic or hemorrhagic complications. Unlike other stroke etiologies, the presence of ICH is often not a contraindication to anticoagulation but necessitates serial assessment for hematoma expansion in this patient population. Venous infarction and hemorrhage may complicate venous thrombosis, particularly cortical venous thrombosis. Imaging features suggesting venous infarction with hemorrhage may include atypical distributions not matching arterial vascular territories, infarcts with cortical sparing, typical parasagittal or temporoparietal location, or dural venous/cortical venous hyperdensity on noncontrast CT suggestive of thrombus. Arteriography Cervicocerebral Catheter-directed cerebral angiography and runoff venography are infrequently necessary in the setting of dural venous sinus thrombosis due to the sensitivity and specificity of CTV and MRV. In the setting of progressive infarct despite adequate medical therapy, catheter-directed angiography and venography may be useful to assess potential endovascular treatment targets. CT Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. However, perfusion imaging is typically a follow-up imaging study after the diagnosis of CVT.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. US Duplex Doppler Carotid Artery In the setting of IPH, US duplex Doppler carotid of the neck is not supported by the literature. US Duplex Doppler Transcranial In the setting of suspected hypertensive hemorrhage, there is no relevant literature to support transcranial Doppler. Variant 7: Adult. Suspected venous sinus thrombosis. Initial imaging. CVT is an uncommon cause for stroke, accounting for approximately 1% to 2% of all strokes [99]. The patients often have hypercoagulable risk factors (cancer, recent oral contraceptive use, and pregnancy) and may present with headaches, seizures, or decreased level of consciousness due to either venous ischemic or hemorrhagic complications. Unlike other stroke etiologies, the presence of ICH is often not a contraindication to anticoagulation but necessitates serial assessment for hematoma expansion in this patient population. Venous infarction and hemorrhage may complicate venous thrombosis, particularly cortical venous thrombosis. Imaging features suggesting venous infarction with hemorrhage may include atypical distributions not matching arterial vascular territories, infarcts with cortical sparing, typical parasagittal or temporoparietal location, or dural venous/cortical venous hyperdensity on noncontrast CT suggestive of thrombus. Arteriography Cervicocerebral Catheter-directed cerebral angiography and runoff venography are infrequently necessary in the setting of dural venous sinus thrombosis due to the sensitivity and specificity of CTV and MRV. In the setting of progressive infarct despite adequate medical therapy, catheter-directed angiography and venography may be useful to assess potential endovascular treatment targets. CT Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. However, perfusion imaging is typically a follow-up imaging study after the diagnosis of CVT.

3149012

acrac_3149012_35

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Moreover, the requirement for iodinated contrast may limit use of CTP in patients with acute or severe chronic renal insufficiency. Cerebrovascular Diseases-Stroke head without and with IV contrast specifically for the evaluation of venous sinus thrombosis unless noncontrast CT is otherwise indicated for parenchymal assessment. CT Head Without IV Contrast Noncontrast CT of the head is essential in the initial evaluation of CVT. The primary usefulness of noncontrast CT of the head in the initial evaluation of CVT is to evaluate for hemorrhagic complication and alternative etiologies. Noncontrast CT may show sinus hyperdensity. However, only 30% of noncontrast head CT examinations are abnormal in the setting of CVT [99]. CTA Neck With IV Contrast There is no relevant literature to support the use of CTA of the neck in the initial evaluation of CVT. CTA of the neck may be useful for endovascular surgical planning for venous sinus thrombectomy, if clinically relevant. CTV Head With IV Contrast CTV of the head is a useful, rapid initial evaluation with a high sensitivity and specificity for detection of CVT. CT is particularly useful when MRI is contraindicated or when MRI artifacts are suspected that could obscure the diagnosis. Specifically, CTV is as accurate in diagnosis of CVT as MRV [101]. MRA Head Without and With IV Contrast There is no relevant literature to support the use of MRA of the head in the initial evaluation of CVT. MRA Head Without IV Contrast There is no relevant literature to support the use of MRA of the head in the initial evaluation of CVT. MRA Neck Without and With IV Contrast There is no relevant literature to support the use of MRA of the neck in the initial evaluation of CVT. MRA Neck Without IV Contrast There is no relevant literature to support the use of MRA of the neck in the initial evaluation of CVT.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Moreover, the requirement for iodinated contrast may limit use of CTP in patients with acute or severe chronic renal insufficiency. Cerebrovascular Diseases-Stroke head without and with IV contrast specifically for the evaluation of venous sinus thrombosis unless noncontrast CT is otherwise indicated for parenchymal assessment. CT Head Without IV Contrast Noncontrast CT of the head is essential in the initial evaluation of CVT. The primary usefulness of noncontrast CT of the head in the initial evaluation of CVT is to evaluate for hemorrhagic complication and alternative etiologies. Noncontrast CT may show sinus hyperdensity. However, only 30% of noncontrast head CT examinations are abnormal in the setting of CVT [99]. CTA Neck With IV Contrast There is no relevant literature to support the use of CTA of the neck in the initial evaluation of CVT. CTA of the neck may be useful for endovascular surgical planning for venous sinus thrombectomy, if clinically relevant. CTV Head With IV Contrast CTV of the head is a useful, rapid initial evaluation with a high sensitivity and specificity for detection of CVT. CT is particularly useful when MRI is contraindicated or when MRI artifacts are suspected that could obscure the diagnosis. Specifically, CTV is as accurate in diagnosis of CVT as MRV [101]. MRA Head Without and With IV Contrast There is no relevant literature to support the use of MRA of the head in the initial evaluation of CVT. MRA Head Without IV Contrast There is no relevant literature to support the use of MRA of the head in the initial evaluation of CVT. MRA Neck Without and With IV Contrast There is no relevant literature to support the use of MRA of the neck in the initial evaluation of CVT. MRA Neck Without IV Contrast There is no relevant literature to support the use of MRA of the neck in the initial evaluation of CVT.

3149012

acrac_3149012_36

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. Although perfusion imaging is not the most appropriate initial imaging study, ASL perfusion is often acquired with conventional brain MRI as part of the diagnostic workup. MRI Head Without and With IV Contrast MRI of the head is a useful initial examination in the workup of CVT. MRI of the head is useful not only for evaluation of the extent of cytotoxic and vasogenic edema but also in the initial detection of petechial hemorrhage and the actual thrombus in many cases. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103]. MRI Head Without IV Contrast MRI of the head is a useful initial examination in the workup of CVT. MRI of the head is useful not only for evaluation of the extent of cytotoxic and vasogenic edema but also in the initial detection of petechial hemorrhage and the actual thrombus in many cases. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103]. Cerebrovascular Diseases-Stroke MRV Head Without and With IV Contrast MRV of the head along with MRI of the head is an essential component of the workup of CVT in most cases.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. Although perfusion imaging is not the most appropriate initial imaging study, ASL perfusion is often acquired with conventional brain MRI as part of the diagnostic workup. MRI Head Without and With IV Contrast MRI of the head is a useful initial examination in the workup of CVT. MRI of the head is useful not only for evaluation of the extent of cytotoxic and vasogenic edema but also in the initial detection of petechial hemorrhage and the actual thrombus in many cases. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103]. MRI Head Without IV Contrast MRI of the head is a useful initial examination in the workup of CVT. MRI of the head is useful not only for evaluation of the extent of cytotoxic and vasogenic edema but also in the initial detection of petechial hemorrhage and the actual thrombus in many cases. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103]. Cerebrovascular Diseases-Stroke MRV Head Without and With IV Contrast MRV of the head along with MRI of the head is an essential component of the workup of CVT in most cases.

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acrac_3149012_37

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

The MRV of the head is useful for confirming the presence of thrombus and ideally consists of both noncontrast TOF and contrast-enhanced MRV. Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], contrast-enhanced and TOF MRV imaging techniques are complementary in that a contrast- enhanced MRV may provide a better assessment of a hypoplastic dural venous sinus with slow flow and TOF MRV mitigates against T1 isointense thrombus, which may mimic normal opacification of the sinus on contrast-enhanced MRV. Additionally, T1 hyperintense thrombus can mimic normal flow and enhancement patterns, which necessitates evaluation with noncontrast MRI. Volumetric MRI sequences are essential for contrast-enhanced MRV. Delayed postcontrast imaging can further increase the sensitivity for detection of T1 isointense thrombus. MRV Head Without IV Contrast MRV of the head along with MRI of the head is an essential component of the workup of CVT in most cases. Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], TOF and phase- contrast MRV are noncontrast alternatives for the diagnosis of CVT. If the findings on noncontrast MRV are unclear, then further imaging with contrast-enhanced CTV or MRV should be considered. US Duplex Doppler Carotid Artery There is no relevant literature to support the use of carotid Doppler in the setting of CVT. However, US assessment of the adjacent venous structures could yield useful information about the extent of the thrombus if extending into the neck. US Duplex Doppler Transcranial There is no relevant literature to support the use of transcranial Doppler in the setting of CVT. Variant 8: Adult. Known venous sinus thrombosis. Surveillance imaging. CVT is an uncommon cause for stroke, accounting for approximately 1% to 2% of all strokes [99].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. The MRV of the head is useful for confirming the presence of thrombus and ideally consists of both noncontrast TOF and contrast-enhanced MRV. Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], contrast-enhanced and TOF MRV imaging techniques are complementary in that a contrast- enhanced MRV may provide a better assessment of a hypoplastic dural venous sinus with slow flow and TOF MRV mitigates against T1 isointense thrombus, which may mimic normal opacification of the sinus on contrast-enhanced MRV. Additionally, T1 hyperintense thrombus can mimic normal flow and enhancement patterns, which necessitates evaluation with noncontrast MRI. Volumetric MRI sequences are essential for contrast-enhanced MRV. Delayed postcontrast imaging can further increase the sensitivity for detection of T1 isointense thrombus. MRV Head Without IV Contrast MRV of the head along with MRI of the head is an essential component of the workup of CVT in most cases. Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], TOF and phase- contrast MRV are noncontrast alternatives for the diagnosis of CVT. If the findings on noncontrast MRV are unclear, then further imaging with contrast-enhanced CTV or MRV should be considered. US Duplex Doppler Carotid Artery There is no relevant literature to support the use of carotid Doppler in the setting of CVT. However, US assessment of the adjacent venous structures could yield useful information about the extent of the thrombus if extending into the neck. US Duplex Doppler Transcranial There is no relevant literature to support the use of transcranial Doppler in the setting of CVT. Variant 8: Adult. Known venous sinus thrombosis. Surveillance imaging. CVT is an uncommon cause for stroke, accounting for approximately 1% to 2% of all strokes [99].

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acrac_3149012_38

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

The patients often have hypercoagulable risk factors (cancer, recent oral contraceptive use, and pregnancy) and may present with headaches, seizures, or decreased level of consciousness due to either venous ischemic or hemorrhagic complications. Unlike other stroke etiologies, the presence of ICH is often not a contraindication to anticoagulation but necessitates serial assessment for hematoma development and/or expansion in the acute and early subacute phases in this patient population. An early follow-up is recommended in patients with CVT with persistent or evolving symptoms despite medical treatment or with symptoms suggestive of propagation of thrombus. In patients with previous CVT who present with recurrent symptoms suggestive of CVT, repeat imaging is also recommended. Serial follow-up at 3 to 6 months after diagnosis is used to assess for recanalization of the occluded cortical vein/sinuses in stable patients. However, recommendations for duration of anticoagulation are not based on the presence or absence of recanalization [99,105]. In the delayed setting, CVT may be complicated by dural arteriovenous fistula, which may necessitate delayed arterial imaging. Arteriography Cervicocerebral Catheter-directed cerebral angiography and venography are infrequently necessary in the setting of dural venous sinus thrombosis due to the sensitivity and specificity of CTV and MRV. In the setting of progressive infarct despite adequate medical therapy, catheter-directed angiography and venography may be useful for the identification of endovascular treatment targets or definitive evaluation for dural arteriovenous fistula development, which may complicate CVT. CT Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. In ongoing surveillance, however, the role for perfusion imaging is limited.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. The patients often have hypercoagulable risk factors (cancer, recent oral contraceptive use, and pregnancy) and may present with headaches, seizures, or decreased level of consciousness due to either venous ischemic or hemorrhagic complications. Unlike other stroke etiologies, the presence of ICH is often not a contraindication to anticoagulation but necessitates serial assessment for hematoma development and/or expansion in the acute and early subacute phases in this patient population. An early follow-up is recommended in patients with CVT with persistent or evolving symptoms despite medical treatment or with symptoms suggestive of propagation of thrombus. In patients with previous CVT who present with recurrent symptoms suggestive of CVT, repeat imaging is also recommended. Serial follow-up at 3 to 6 months after diagnosis is used to assess for recanalization of the occluded cortical vein/sinuses in stable patients. However, recommendations for duration of anticoagulation are not based on the presence or absence of recanalization [99,105]. In the delayed setting, CVT may be complicated by dural arteriovenous fistula, which may necessitate delayed arterial imaging. Arteriography Cervicocerebral Catheter-directed cerebral angiography and venography are infrequently necessary in the setting of dural venous sinus thrombosis due to the sensitivity and specificity of CTV and MRV. In the setting of progressive infarct despite adequate medical therapy, catheter-directed angiography and venography may be useful for the identification of endovascular treatment targets or definitive evaluation for dural arteriovenous fistula development, which may complicate CVT. CT Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of CVT [100]. In ongoing surveillance, however, the role for perfusion imaging is limited.

3149012

acrac_3149012_39

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CT Head Without IV Contrast Serial follow-up noncontrast CT of the head is useful in the patient with persistent or evolving symptoms despite medical treatment or with symptoms suggestive of propagation of thrombus. This is particularly useful in the late acute and subacute phases following initial presentation. Noncontrast CT may show sinus hyperdensity, which may be useful in early evaluation of thrombus extent; however, only 30% of noncontrast head CT examinations are abnormal in the setting of CVT [99]. CTA Neck With IV Contrast There is no relevant literature to support the use of CTA of the neck in the setting of known CVT. CTV Head With IV Contrast In the setting of known CVT, CTV of the head may be useful in assessing thrombus burden; however, there are no data to support its use in determining the duration of anticoagulation. CTV is as accurate in evaluation of CVT as MRV [101,106]. CTV has high spatial resolution and is not affected by typical MRI artifacts that may complicate thrombus imaging. CTV may be useful when MRV is degraded and accurate measurement of thrombus extent is desired or when thrombus involves hypoplastic dural sinuses or cortical branches. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the setting of known CVT. MRA Neck Without and With IV Contrast There is no relevant literature to support the use of MRA of the neck in the setting of known CVT. MRA Neck With IV Contrast There is no relevant literature to support the use of MRA of the neck in the setting of known CVT. MRI Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of known CVT [100]. CTP is not typically performed, however, in ongoing surveillance imaging in the absence of changes in clinical status.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without IV Contrast Serial follow-up noncontrast CT of the head is useful in the patient with persistent or evolving symptoms despite medical treatment or with symptoms suggestive of propagation of thrombus. This is particularly useful in the late acute and subacute phases following initial presentation. Noncontrast CT may show sinus hyperdensity, which may be useful in early evaluation of thrombus extent; however, only 30% of noncontrast head CT examinations are abnormal in the setting of CVT [99]. CTA Neck With IV Contrast There is no relevant literature to support the use of CTA of the neck in the setting of known CVT. CTV Head With IV Contrast In the setting of known CVT, CTV of the head may be useful in assessing thrombus burden; however, there are no data to support its use in determining the duration of anticoagulation. CTV is as accurate in evaluation of CVT as MRV [101,106]. CTV has high spatial resolution and is not affected by typical MRI artifacts that may complicate thrombus imaging. CTV may be useful when MRV is degraded and accurate measurement of thrombus extent is desired or when thrombus involves hypoplastic dural sinuses or cortical branches. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the setting of known CVT. MRA Neck Without and With IV Contrast There is no relevant literature to support the use of MRA of the neck in the setting of known CVT. MRA Neck With IV Contrast There is no relevant literature to support the use of MRA of the neck in the setting of known CVT. MRI Head Perfusion With IV Contrast Some studies demonstrate a possible role for perfusion imaging in prognostic evaluation of the ischemic penumbra in the setting of known CVT [100]. CTP is not typically performed, however, in ongoing surveillance imaging in the absence of changes in clinical status.

3149012

acrac_3149012_40

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI Head Without and With IV Contrast MRI of the head is useful in the ongoing evaluation of CVT in evaluating for progressive ischemic and hemorrhagic venous infarct. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Delayed postcontrast imaging can further improve assessment of T1 hyperintense thrombus burden. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103]. MRI Head Without IV Contrast MRI of the head is useful in the ongoing evaluation of CVT in evaluating for progressive ischemic and hemorrhagic venous infarct. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation Cerebrovascular Diseases-Stroke of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Delayed postcontrast imaging can further improve assessment of T1 hyperintense thrombus burden. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103]. MRV Head Without and With IV Contrast Although contrast-enhanced venography is the most accurate means of assessment for CVT, contrast-enhanced and TOF MRV imaging techniques are complementary, in that a contrast-enhanced MRV may provide a better assessment of a hypoplastic dural venous sinus with slow flow and TOF MRV mitigates against T1 isointense thrombus, which may mimic a normal opacification of the sinus on contrast-enhanced MRV [104].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without and With IV Contrast MRI of the head is useful in the ongoing evaluation of CVT in evaluating for progressive ischemic and hemorrhagic venous infarct. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Delayed postcontrast imaging can further improve assessment of T1 hyperintense thrombus burden. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103]. MRI Head Without IV Contrast MRI of the head is useful in the ongoing evaluation of CVT in evaluating for progressive ischemic and hemorrhagic venous infarct. Contrast is not always required for structural brain imaging but adds to the overall MRI evaluation Cerebrovascular Diseases-Stroke of venous sinus thrombosis [102] and is commonly administered when MRI is performed together with MRV. Delayed postcontrast imaging can further improve assessment of T1 hyperintense thrombus burden. Noncontrast black blood thrombus imaging may approach the accuracy of contrast-enhanced MRV and negate the need for either MRV or contrast-enhanced examination, but it is less well-validated in clinical practice [103]. MRV Head Without and With IV Contrast Although contrast-enhanced venography is the most accurate means of assessment for CVT, contrast-enhanced and TOF MRV imaging techniques are complementary, in that a contrast-enhanced MRV may provide a better assessment of a hypoplastic dural venous sinus with slow flow and TOF MRV mitigates against T1 isointense thrombus, which may mimic a normal opacification of the sinus on contrast-enhanced MRV [104].

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acrac_3149012_41

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Additionally, T1 hyperintense thrombus can mimic normal flow and enhancement patterns, which necessitates evaluation with noncontrast MRI imaging. Volumetric MRI sequences are essential for contrast-enhanced MRV. Delayed postcontrast imaging can further increase the sensitivity for detection of T1 isointense thrombus. MRV Head Without IV Contrast Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], TOF and phase- contrast MRV are noncontrast alternatives for the diagnosis of CVT. If the findings on noncontrast MRV are unclear, then further imaging with contrast-enhanced CTV or MRV should be considered. US Duplex Doppler Carotid Artery There is no relevant literature to support the use of carotid Doppler in the setting of CVT. However, US assessment of the adjacent venous structures could yield useful information about the extent of the thrombus if extending into the neck. US Duplex Doppler Transcranial There is no relevant literature to support the use of transcranial Doppler in the setting of CVT. Variant 9: Adult. Asymptomatic cervical bruit. Initial imaging. Cervical carotid bruit is an important diagnostic sign of potential underlying carotid stenosis because patients with carotid bruit are >50% more likely to harbor hemodynamically significant internal carotid stenosis. Although the advent of electronic auscultation has driven the negative predictive value to an all-time high, the positive predictive value is now at an all-time low, in the 30% range, which increases the importance of radiographic evaluation following detection of carotid bruit [107]. In the patient with recent TIA or minor stroke who is a candidate for CEA or stenting, the presence or absence of carotid bruit does not alter the necessity or urgency of evaluating the degree of carotid stenosis (see Variants 1-5).

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Additionally, T1 hyperintense thrombus can mimic normal flow and enhancement patterns, which necessitates evaluation with noncontrast MRI imaging. Volumetric MRI sequences are essential for contrast-enhanced MRV. Delayed postcontrast imaging can further increase the sensitivity for detection of T1 isointense thrombus. MRV Head Without IV Contrast Although contrast-enhanced venography is the most accurate means of assessment for CVT [104], TOF and phase- contrast MRV are noncontrast alternatives for the diagnosis of CVT. If the findings on noncontrast MRV are unclear, then further imaging with contrast-enhanced CTV or MRV should be considered. US Duplex Doppler Carotid Artery There is no relevant literature to support the use of carotid Doppler in the setting of CVT. However, US assessment of the adjacent venous structures could yield useful information about the extent of the thrombus if extending into the neck. US Duplex Doppler Transcranial There is no relevant literature to support the use of transcranial Doppler in the setting of CVT. Variant 9: Adult. Asymptomatic cervical bruit. Initial imaging. Cervical carotid bruit is an important diagnostic sign of potential underlying carotid stenosis because patients with carotid bruit are >50% more likely to harbor hemodynamically significant internal carotid stenosis. Although the advent of electronic auscultation has driven the negative predictive value to an all-time high, the positive predictive value is now at an all-time low, in the 30% range, which increases the importance of radiographic evaluation following detection of carotid bruit [107]. In the patient with recent TIA or minor stroke who is a candidate for CEA or stenting, the presence or absence of carotid bruit does not alter the necessity or urgency of evaluating the degree of carotid stenosis (see Variants 1-5).

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acrac_3149012_42

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

For asymptomatic patients, advances in medical therapy have rendered data from older clinical trials on the benefit of endarterectomy out of date, and thus the value of determining the degree of stenosis in these patients is less clear and currently the subject of a large randomized clinical trial [108- 110]. Currently, guidelines from professional societies continue to recommend CEA for certain selected patients with asymptomatic stenosis in which the degree of stenosis is an important deciding factor [111,112]. Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. Catheter-directed angiography is the most accurate means of delineating the degree of vascular stenosis and can also be useful in the evaluation of collateral circulation. However, the usefulness of this technique for screening is obviated by the invasive nature of the examination. Moreover, there is no literature supporting cerebral angiography as the initial imaging test in evaluation of a carotid bruit. Nonetheless, cerebral angiography may be necessary in some cases after the initial diagnosis of hemodynamically significant carotid stenosis is made on noninvasive imaging. CT Head Perfusion With IV Contrast CT head perfusion imaging may help delineate the hemodynamic significance of a known carotid lesion and the collateral support in each distribution. However, there is no literature to support the use of CTP for the initial detection of hemodynamically significant carotid disease in the asymptomatic patient with a carotid bruit. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of the asymptomatic patient with a carotid bruit. Cerebrovascular Diseases-Stroke

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. For asymptomatic patients, advances in medical therapy have rendered data from older clinical trials on the benefit of endarterectomy out of date, and thus the value of determining the degree of stenosis in these patients is less clear and currently the subject of a large randomized clinical trial [108- 110]. Currently, guidelines from professional societies continue to recommend CEA for certain selected patients with asymptomatic stenosis in which the degree of stenosis is an important deciding factor [111,112]. Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. Catheter-directed angiography is the most accurate means of delineating the degree of vascular stenosis and can also be useful in the evaluation of collateral circulation. However, the usefulness of this technique for screening is obviated by the invasive nature of the examination. Moreover, there is no literature supporting cerebral angiography as the initial imaging test in evaluation of a carotid bruit. Nonetheless, cerebral angiography may be necessary in some cases after the initial diagnosis of hemodynamically significant carotid stenosis is made on noninvasive imaging. CT Head Perfusion With IV Contrast CT head perfusion imaging may help delineate the hemodynamic significance of a known carotid lesion and the collateral support in each distribution. However, there is no literature to support the use of CTP for the initial detection of hemodynamically significant carotid disease in the asymptomatic patient with a carotid bruit. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of the asymptomatic patient with a carotid bruit. Cerebrovascular Diseases-Stroke

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acrac_3149012_43

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of the asymptomatic patient with a carotid bruit. CT Head Without IV Contrast There is no literature to support noncontrast CT of the head in the initial workup of the asymptomatic patient with a carotid bruit. Noncontrast CT of the head is useful in evaluating for the sequela of known asymptomatic carotid stenosis such as clinically silent strokes or microvascular ischemic changes. However, MRI is much more sensitive in evaluating microvascular ischemic changes or recent strokes. Symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging. CTA Head With IV Contrast CTA of the head may be useful in treatment planning for patients with an established diagnosis of asymptomatic carotid stenosis. However, there is no literature to support CTA of the head in the initial workup for the asymptomatic patient with a carotid bruit. CTA Neck With IV Contrast CTA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis as well as status of the other cervical vessels. Specifically, CTA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. CTA of the neck is also useful for treatment planning [114]. However, CTA of the neck may also underestimate the degree of stenosis in the setting of tortuosity or calcifications similar in density to contrast media [24]. Conversely, CTA may overestimate stenosis in the setting of very severe near occlusive stenosis [115]. Dual-energy CT may help limit overestimation of stenosis in some instances [116].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the evaluation of the asymptomatic patient with a carotid bruit. CT Head Without IV Contrast There is no literature to support noncontrast CT of the head in the initial workup of the asymptomatic patient with a carotid bruit. Noncontrast CT of the head is useful in evaluating for the sequela of known asymptomatic carotid stenosis such as clinically silent strokes or microvascular ischemic changes. However, MRI is much more sensitive in evaluating microvascular ischemic changes or recent strokes. Symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging. CTA Head With IV Contrast CTA of the head may be useful in treatment planning for patients with an established diagnosis of asymptomatic carotid stenosis. However, there is no literature to support CTA of the head in the initial workup for the asymptomatic patient with a carotid bruit. CTA Neck With IV Contrast CTA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis as well as status of the other cervical vessels. Specifically, CTA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. CTA of the neck is also useful for treatment planning [114]. However, CTA of the neck may also underestimate the degree of stenosis in the setting of tortuosity or calcifications similar in density to contrast media [24]. Conversely, CTA may overestimate stenosis in the setting of very severe near occlusive stenosis [115]. Dual-energy CT may help limit overestimation of stenosis in some instances [116].

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acrac_3149012_44

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

However, the requirement for iodinated contrast detracts from this examination in comparison to Doppler and MRA. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the evaluation of the asymptomatic patient with a carotid bruit. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of the asymptomatic patient with a carotid bruit. MRA Head Without IV Contrast There is no literature to support MRA of the head in the initial workup of the asymptomatic patient with a carotid bruit. MRA of the head may be useful in treatment planning for patients with an established diagnosis of carotid stenosis. Intracranial collateral characterization may be important when considering proximal embolic protection strategies. MRA Neck Without and With IV Contrast MRA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis, which will limit both false-positives and false-negatives. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over- or underestimation of the degree of disease by carotid Doppler, respectively [113]. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast- enhanced MRA of the neck has a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. However, the requirement for iodinated contrast detracts from this examination in comparison to Doppler and MRA. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the evaluation of the asymptomatic patient with a carotid bruit. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the evaluation of the asymptomatic patient with a carotid bruit. MRA Head Without IV Contrast There is no literature to support MRA of the head in the initial workup of the asymptomatic patient with a carotid bruit. MRA of the head may be useful in treatment planning for patients with an established diagnosis of carotid stenosis. Intracranial collateral characterization may be important when considering proximal embolic protection strategies. MRA Neck Without and With IV Contrast MRA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis, which will limit both false-positives and false-negatives. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over- or underestimation of the degree of disease by carotid Doppler, respectively [113]. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast- enhanced MRA of the neck has a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114].

3149012

acrac_3149012_45

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Additionally, composition of carotid plaque including intraplaque hemorrhage on magnetization-prepared rapid acquisition gradient echo images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [118,119]. MRA Neck Without IV Contrast MRA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis, which will limit both false-positives and false-negatives. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result Cerebrovascular Diseases-Stroke in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast- enhanced MRA of the neck has a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, composition of carotid plaque including intraplaque hemorrhage on magnetization-prepared rapid acquisition gradient echo images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [118,119]. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Additionally, composition of carotid plaque including intraplaque hemorrhage on magnetization-prepared rapid acquisition gradient echo images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [118,119]. MRA Neck Without IV Contrast MRA of the neck is useful in the initial workup of the asymptomatic patient with a carotid bruit owing to the anatomic assessment of stenosis, which will limit both false-positives and false-negatives. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result Cerebrovascular Diseases-Stroke in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast- enhanced MRA of the neck has a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, composition of carotid plaque including intraplaque hemorrhage on magnetization-prepared rapid acquisition gradient echo images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [118,119]. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution.

3149012

acrac_3149012_46

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

However, there is no literature to support the use of MRI perfusion in the initial evaluation of the asymptomatic patient with a carotid bruit. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the evaluation of the asymptomatic patient with a carotid bruit. MRI Head Without IV Contrast There is no literature to support MRI of the head in the initial workup for the asymptomatic patient with a carotid bruit. MRI of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of asymptomatic carotid stenosis. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of the asymptomatic patient with a carotid bruit. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of the asymptomatic patient with a carotid bruit. US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very accurate and useful screening test in the evaluation of the extracranial vasculature for carotid stenosis in the asymptomatic patient with a carotid bruit, which stratifies patients into groups of mild (<50%), moderate (50%-69%), and severe (>70%) stenosis. Specifically, carotid Doppler has a 90% sensitivity and a 94% specificity in the identification of clinically significant >70% stenosis, which might warrant surgical intervention [111,112,120]. The lack of need for IV contrast decreases the risk to the patient.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. However, there is no literature to support the use of MRI perfusion in the initial evaluation of the asymptomatic patient with a carotid bruit. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the evaluation of the asymptomatic patient with a carotid bruit. MRI Head Without IV Contrast There is no literature to support MRI of the head in the initial workup for the asymptomatic patient with a carotid bruit. MRI of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of asymptomatic carotid stenosis. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of the asymptomatic patient with a carotid bruit. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the evaluation of the asymptomatic patient with a carotid bruit. US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very accurate and useful screening test in the evaluation of the extracranial vasculature for carotid stenosis in the asymptomatic patient with a carotid bruit, which stratifies patients into groups of mild (<50%), moderate (50%-69%), and severe (>70%) stenosis. Specifically, carotid Doppler has a 90% sensitivity and a 94% specificity in the identification of clinically significant >70% stenosis, which might warrant surgical intervention [111,112,120]. The lack of need for IV contrast decreases the risk to the patient.

3149012

acrac_3149012_47

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

However, caution must be observed when evaluating patients with either extremely severe stenosis or multivessel involvement because Doppler can overestimate the degree of stenosis in the setting of contralateral disease or multivessel disease or underestimate the stenosis in the setting of critical high-grade stenosis, which may result in artifactual elevation of velocity or reduction in velocity, respectively. Clinically significant carotid disease may trigger further anatomic imaging to characterize stenosis and exclude confounding multivessel disease; however, there is no consensus on this matter. In otherwise uncomplicated cases, US imaging alone may be the only necessary examination in a patient with carotid bruit. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in determining the hemodynamic significance of a known carotid stenosis. However, there is no literature to support transcranial Doppler in the initial workup of the asymptomatic patient with a carotid bruit. Variant 10: Adult. Asymptomatic carotid stenosis. Surveillance imaging. Asymptomatic carotid stenosis is an important diagnostic finding, which may progress to symptomatic stenosis. For asymptomatic patients, advances in medical therapy have rendered data from older clinical trials on the benefit of endarterectomy out of date, and thus the value of determining the degree of stenosis in these patients is less clear and currently the subject of a large randomized clinical trial [108-110]. Currently, guidelines from professional societies continue to recommend CEA for certain selected patients with asymptomatic stenosis in which the degree of stenosis is an important deciding factor [111,112]. Surveillance imaging is an important tool in the management Cerebrovascular Diseases-Stroke of asymptomatic carotid stenosis.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. However, caution must be observed when evaluating patients with either extremely severe stenosis or multivessel involvement because Doppler can overestimate the degree of stenosis in the setting of contralateral disease or multivessel disease or underestimate the stenosis in the setting of critical high-grade stenosis, which may result in artifactual elevation of velocity or reduction in velocity, respectively. Clinically significant carotid disease may trigger further anatomic imaging to characterize stenosis and exclude confounding multivessel disease; however, there is no consensus on this matter. In otherwise uncomplicated cases, US imaging alone may be the only necessary examination in a patient with carotid bruit. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in determining the hemodynamic significance of a known carotid stenosis. However, there is no literature to support transcranial Doppler in the initial workup of the asymptomatic patient with a carotid bruit. Variant 10: Adult. Asymptomatic carotid stenosis. Surveillance imaging. Asymptomatic carotid stenosis is an important diagnostic finding, which may progress to symptomatic stenosis. For asymptomatic patients, advances in medical therapy have rendered data from older clinical trials on the benefit of endarterectomy out of date, and thus the value of determining the degree of stenosis in these patients is less clear and currently the subject of a large randomized clinical trial [108-110]. Currently, guidelines from professional societies continue to recommend CEA for certain selected patients with asymptomatic stenosis in which the degree of stenosis is an important deciding factor [111,112]. Surveillance imaging is an important tool in the management Cerebrovascular Diseases-Stroke of asymptomatic carotid stenosis.

3149012

acrac_3149012_48

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

From a management prospective, carotid stenosis is divided into 3 categories based on the degree of stenosis including mild (<50%), moderate (50%-69%), and severe (>70%) stenosis, with the latter 2 categories having a higher probability of hemodynamic significance subsequent ipsilateral stroke [121,122]. The risk for progression of carotid stenosis is poorly characterized. In small case-controlled studies, the risk of mild or moderate stenosis to progress is between 30% and 40% within the ensuing 3 years [123]. The type of surveillance imaging indicated is informed by the degree of stenosis and, thereby, concern of the hemodynamic significance of the stenosis. In most cases, surveillance imaging of asymptomatic carotid disease focuses on the area of stenosis guided by the character of the stenosis and presence of involvement of the other cerebrovascular territories. However, if hemodynamically significant stenosis is suspected, parenchymal imaging, physiologic imaging, and invasive imaging may be useful to guide management of asymptomatic carotid disease [112]. For symptomatic carotid disease, please see Variants 1 to 5 for indicated imaging procedures. Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. Catheter-directed angiography accurately measures the degree of vascular stenosis and can also be useful in the evaluation of collateral circulation. However, the usefulness of this technique for surveillance imaging is obviated by the invasive nature of the examination and availability of both sensitive and specific noninvasive tests. Although cerebral angiography is not used as routine surveillance imaging for asymptomatic carotid disease, angiography can be useful in some cases of known, hemodynamically significant stenosis to determine appropriate treatment options.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. From a management prospective, carotid stenosis is divided into 3 categories based on the degree of stenosis including mild (<50%), moderate (50%-69%), and severe (>70%) stenosis, with the latter 2 categories having a higher probability of hemodynamic significance subsequent ipsilateral stroke [121,122]. The risk for progression of carotid stenosis is poorly characterized. In small case-controlled studies, the risk of mild or moderate stenosis to progress is between 30% and 40% within the ensuing 3 years [123]. The type of surveillance imaging indicated is informed by the degree of stenosis and, thereby, concern of the hemodynamic significance of the stenosis. In most cases, surveillance imaging of asymptomatic carotid disease focuses on the area of stenosis guided by the character of the stenosis and presence of involvement of the other cerebrovascular territories. However, if hemodynamically significant stenosis is suspected, parenchymal imaging, physiologic imaging, and invasive imaging may be useful to guide management of asymptomatic carotid disease [112]. For symptomatic carotid disease, please see Variants 1 to 5 for indicated imaging procedures. Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. Catheter-directed angiography accurately measures the degree of vascular stenosis and can also be useful in the evaluation of collateral circulation. However, the usefulness of this technique for surveillance imaging is obviated by the invasive nature of the examination and availability of both sensitive and specific noninvasive tests. Although cerebral angiography is not used as routine surveillance imaging for asymptomatic carotid disease, angiography can be useful in some cases of known, hemodynamically significant stenosis to determine appropriate treatment options.

3149012

acrac_3149012_49

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CT Head Perfusion With IV Contrast CT head perfusion imaging may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution. More specifically, perfusion imaging may be helpful in cases of moderate stenosis, approaching 70% or severe stenosis [124]. However, there is no literature to support the use of CTP as the initial imaging test in surveillance imaging of asymptomatic carotid disease. The need for IV contrast and relative lack of sensitivity for white matter ischemic changes detracts from the routine use of this study in surveillance imaging. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the surveillance imaging of asymptomatic carotid stenosis. CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the surveillance imaging of asymptomatic carotid stenosis. CT Head Without IV Contrast There is no literature to support noncontrast CT of the head in the routine surveillance imaging of asymptomatic carotid disease. Noncontrast CT of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of carotid stenosis, which is particularly important in cases of hemodynamically significant stenosis. However, MRI is much more sensitive in evaluating microvascular ischemic changes or recent strokes. Symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging. CTA Head With IV Contrast There is no literature to support CTA of the head in routine surveillance imaging of known asymptomatic carotid disease with no future treatment plans.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast CT head perfusion imaging may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution. More specifically, perfusion imaging may be helpful in cases of moderate stenosis, approaching 70% or severe stenosis [124]. However, there is no literature to support the use of CTP as the initial imaging test in surveillance imaging of asymptomatic carotid disease. The need for IV contrast and relative lack of sensitivity for white matter ischemic changes detracts from the routine use of this study in surveillance imaging. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the surveillance imaging of asymptomatic carotid stenosis. CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the surveillance imaging of asymptomatic carotid stenosis. CT Head Without IV Contrast There is no literature to support noncontrast CT of the head in the routine surveillance imaging of asymptomatic carotid disease. Noncontrast CT of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of carotid stenosis, which is particularly important in cases of hemodynamically significant stenosis. However, MRI is much more sensitive in evaluating microvascular ischemic changes or recent strokes. Symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging. CTA Head With IV Contrast There is no literature to support CTA of the head in routine surveillance imaging of known asymptomatic carotid disease with no future treatment plans.

3149012

acrac_3149012_50

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CTA of the head may be useful in treatment planning for patients with an established diagnosis of hemodynamically significant asymptomatic carotid stenosis. Specifically, intracranial collateral characterization may be important when considering both the initial decision to treat and treatment involving proximal embolic protection strategies. CTA Neck With IV Contrast CTA of the neck is useful in the surveillance imaging of some patients with asymptomatic carotid stenosis owing to the anatomic assessment of stenosis. Specifically, CTA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. CTA of the neck is also useful for treatment planning [114]. However, CTA of the neck may also underestimate the degree of stenosis in the setting of tortuosity or calcifications similar in density to contrast media [80]. Conversely, CTA may overestimate stenosis in the setting of very severe Cerebrovascular Diseases-Stroke near occlusive stenosis [115]. Dual-energy CT may help limit the overestimation of stenosis in some instances [116]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the surveillance imaging of asymptomatic carotid stenosis. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the surveillance imaging of asymptomatic carotid stenosis. MRA Head Without IV Contrast There is no literature to support MRA of the head as in ongoing routine surveillance imaging of known asymptomatic carotid disease. MRA of the head may be useful in treatment planning for patients with an established diagnosis of asymptomatic carotid stenosis.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA of the head may be useful in treatment planning for patients with an established diagnosis of hemodynamically significant asymptomatic carotid stenosis. Specifically, intracranial collateral characterization may be important when considering both the initial decision to treat and treatment involving proximal embolic protection strategies. CTA Neck With IV Contrast CTA of the neck is useful in the surveillance imaging of some patients with asymptomatic carotid stenosis owing to the anatomic assessment of stenosis. Specifically, CTA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. CTA of the neck is also useful for treatment planning [114]. However, CTA of the neck may also underestimate the degree of stenosis in the setting of tortuosity or calcifications similar in density to contrast media [80]. Conversely, CTA may overestimate stenosis in the setting of very severe Cerebrovascular Diseases-Stroke near occlusive stenosis [115]. Dual-energy CT may help limit the overestimation of stenosis in some instances [116]. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the surveillance imaging of asymptomatic carotid stenosis. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the surveillance imaging of asymptomatic carotid stenosis. MRA Head Without IV Contrast There is no literature to support MRA of the head as in ongoing routine surveillance imaging of known asymptomatic carotid disease. MRA of the head may be useful in treatment planning for patients with an established diagnosis of asymptomatic carotid stenosis.

3149012

acrac_3149012_51

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Specifically, intracranial collateral characterization may be important when considering both the initial decision to treat and treatment involving proximal embolic protection strategies. MRA Neck Without and With IV Contrast MRA of the neck is useful in the surveillance imaging of some patients with asymptomatic carotid stenosis owing to the anatomic assessment of stenosis and can be useful for treatment planning. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast-enhanced and TOF MRA of the neck have similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, anatomical features of carotid plaque including intraplaque high-intensity signal on 3-D TOF source images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [85,118,119]. MRA Neck Without IV Contrast MRA of the neck is useful in the surveillance imaging of some patients with asymptomatic carotid stenosis owing to the anatomic assessment of stenosis and can be useful for treatment planning. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over- or underestimation of the degree of disease by carotid Doppler, respectively [113].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Specifically, intracranial collateral characterization may be important when considering both the initial decision to treat and treatment involving proximal embolic protection strategies. MRA Neck Without and With IV Contrast MRA of the neck is useful in the surveillance imaging of some patients with asymptomatic carotid stenosis owing to the anatomic assessment of stenosis and can be useful for treatment planning. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over or underestimation of the degree of disease by carotid Doppler, respectively [113]. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast-enhanced and TOF MRA of the neck have similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, anatomical features of carotid plaque including intraplaque high-intensity signal on 3-D TOF source images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [85,118,119]. MRA Neck Without IV Contrast MRA of the neck is useful in the surveillance imaging of some patients with asymptomatic carotid stenosis owing to the anatomic assessment of stenosis and can be useful for treatment planning. Specifically, MRA of the neck is helpful when multivessel cerebrovascular disease or very severe stenosis is present, which might result in artifactual over- or underestimation of the degree of disease by carotid Doppler, respectively [113].

3149012

acrac_3149012_52

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast-enhanced and TOF MRA of the neck have a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, anatomical features of carotid plaque including intraplaque high-intensity signal on 3-D TOF source images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [85,118,119]. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution. More specifically, perfusion imaging may be helpful in cases of moderate stenosis, approaching 70% or severe stenosis [124]. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the surveillance imaging of asymptomatic carotid stenosis. MRI Head Without IV Contrast MRI of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of carotid stenosis, which is particularly important in cases of hemodynamically significant stenosis. There may be a role for noncontrast MRI of the head Cerebrovascular Diseases-Stroke when monitoring patients with risk factors for stroke or known carotid stenosis.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Noncontrast MRA of the neck may overestimate the degree of stenosis when severe and/or near occlusive. Contrast administration can reduce the degree of overestimation of the degree of stenosis in some cases. However, contrast-enhanced and TOF MRA of the neck have a similar sensitivity for the detection of >70% stenosis of the carotid when 2-D and 3-D techniques of TOF are combined [27,117]. MRA of the neck may also be useful for treatment planning. However, the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used [114]. Additionally, anatomical features of carotid plaque including intraplaque high-intensity signal on 3-D TOF source images can be useful predictors of future stroke risk, beyond assessing the degree of luminal narrowing [85,118,119]. MRI Head Perfusion With IV Contrast Contrast-enhanced MRI head perfusion imaging (or, if available, noncontrast ASL perfusion) may help delineate the hemodynamic significance of a known asymptomatic carotid lesion and the collateral support in each distribution. More specifically, perfusion imaging may be helpful in cases of moderate stenosis, approaching 70% or severe stenosis [124]. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the surveillance imaging of asymptomatic carotid stenosis. MRI Head Without IV Contrast MRI of the head is useful in evaluating for the sequela of carotid stenosis such as clinically silent strokes or microvascular ischemic changes in the setting of an established diagnosis of carotid stenosis, which is particularly important in cases of hemodynamically significant stenosis. There may be a role for noncontrast MRI of the head Cerebrovascular Diseases-Stroke when monitoring patients with risk factors for stroke or known carotid stenosis.

3149012

acrac_3149012_53

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

However, symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the surveillance imaging of asymptomatic carotid stenosis. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the surveillance imaging of asymptomatic carotid stenosis. US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very accurate and useful test in the evaluation of the extracranial vasculature in the setting of carotid stenosis, which stratifies patients into groups of mild (<50%), moderate (50%-69%), and severe (>70%) stenosis. Specifically, carotid Doppler has a 90% sensitivity and a 94% specificity in the identification of clinically significant >70% stenosis, which might warrant surgical intervention [120]. The lack of need for IV contrast decreases the risk to the patient. However, caution must be observed when evaluating patients with either extremely severe stenosis or multivessel involvement because Doppler can overestimate the degree of stenosis in the setting of contralateral disease or multivessel disease or underestimate the stenosis in the setting of critical high- grade stenosis, which may result in artifactual elevation of velocity or reduction in velocity, respectively. In the absence of suspected confounding factors that might result in Doppler error or active treatment plan, US imaging may be the only indicated examination in a patient with carotid bruit. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in determining the hemodynamic significance of a known carotid stenosis. However, there is no literature to support transcranial Doppler in the surveillance imaging of asymptomatic carotid stenosis.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. However, symptomatic carotid disease should be evaluated relative to the underlying symptoms. Please see Variants 1 to 5 for a discussion of appropriate imaging. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the surveillance imaging of asymptomatic carotid stenosis. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the surveillance imaging of asymptomatic carotid stenosis. US Duplex Doppler Carotid Artery Duplex carotid Doppler is a very accurate and useful test in the evaluation of the extracranial vasculature in the setting of carotid stenosis, which stratifies patients into groups of mild (<50%), moderate (50%-69%), and severe (>70%) stenosis. Specifically, carotid Doppler has a 90% sensitivity and a 94% specificity in the identification of clinically significant >70% stenosis, which might warrant surgical intervention [120]. The lack of need for IV contrast decreases the risk to the patient. However, caution must be observed when evaluating patients with either extremely severe stenosis or multivessel involvement because Doppler can overestimate the degree of stenosis in the setting of contralateral disease or multivessel disease or underestimate the stenosis in the setting of critical high- grade stenosis, which may result in artifactual elevation of velocity or reduction in velocity, respectively. In the absence of suspected confounding factors that might result in Doppler error or active treatment plan, US imaging may be the only indicated examination in a patient with carotid bruit. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in determining the hemodynamic significance of a known carotid stenosis. However, there is no literature to support transcranial Doppler in the surveillance imaging of asymptomatic carotid stenosis.

3149012

acrac_3149012_54

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. As such, catheter-directed angiography is the most accurate means of grading a cervical dissection, delineating the degree of associated stenosis, and may also be useful in assessment of collateral circulation. Additionally, some subtle dissections may be more apparent due to higher spatial resolution. However, the usefulness of this technique in screening for dissection is obviated by the invasive nature of the test. There is no literature supporting cerebral angiography as the initial imaging test for suspected cervical vascular dissection. Cervicocerebral angiography may influence treatment options after the initial diagnosis of dissection in patients with severe presenting symptoms such as focal neurological deficits [126]; however, the degree of stenosis may not influence the rate of further stroke [127,128]. Cerebrovascular Diseases-Stroke CT Head Perfusion With IV Contrast There is no literature to support the use of CTP in the initial imaging of suspected cervical vascular dissection or injury. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the initial imaging of suspected cervical vascular dissection or injury. CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the initial imaging of suspected cervical vascular dissection or injury. CT Head Without IV Contrast Noncontrast CT may be useful in the setting of a known dissection to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation or in the exclusion of ICH before the initiation of anticoagulation or antiplatelet therapy for a known dissection. However, MRI is much more sensitive in evaluating recent strokes.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Arteriography Cervicocerebral Catheter-directed cerebral angiography has the highest spatial resolution and temporal resolution of any vascular study. As such, catheter-directed angiography is the most accurate means of grading a cervical dissection, delineating the degree of associated stenosis, and may also be useful in assessment of collateral circulation. Additionally, some subtle dissections may be more apparent due to higher spatial resolution. However, the usefulness of this technique in screening for dissection is obviated by the invasive nature of the test. There is no literature supporting cerebral angiography as the initial imaging test for suspected cervical vascular dissection. Cervicocerebral angiography may influence treatment options after the initial diagnosis of dissection in patients with severe presenting symptoms such as focal neurological deficits [126]; however, the degree of stenosis may not influence the rate of further stroke [127,128]. Cerebrovascular Diseases-Stroke CT Head Perfusion With IV Contrast There is no literature to support the use of CTP in the initial imaging of suspected cervical vascular dissection or injury. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the initial imaging of suspected cervical vascular dissection or injury. CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the initial imaging of suspected cervical vascular dissection or injury. CT Head Without IV Contrast Noncontrast CT may be useful in the setting of a known dissection to evaluate for complications such as hemorrhagic conversion, mass effect, and herniation or in the exclusion of ICH before the initiation of anticoagulation or antiplatelet therapy for a known dissection. However, MRI is much more sensitive in evaluating recent strokes.

3149012

acrac_3149012_55

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CTA Head With IV Contrast CTA of the head may be useful in the evaluation for intracranial extension of a known cervical dissection. CTA of the head may also be useful for evaluation of intracranial collaterals of the circle of Willis and excluding associated intracranial LVO, which is important in stroke risk stratification and treatment strategies. As such, although a CTA of the head may be necessary in the workup of a known cervical artery dissection, there is no literature to support CTA of the head in the initial screening examination for a suspected cervical artery dissection. CTA Neck With IV Contrast CTA of the neck is useful in the initial screening examination for suspected cervical vascular dissection owing to rapid acquisition and high spatial resolution of the examination. Rapid examination is important in the evaluation for suspected cervical dissection due to the stroke risk associated with treatment delays. The high resolution of CTA neck allows for the detection of fairly subtle dissections with high sensitivity for both cervical carotid and vertebral artery dissections with a sensitivity and specificity approaching 98% [129]. CTA neck can rapidly and accurately grade the degree of luminal narrowing, vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap, which may make it preferable to MRA [130]. CTA neck also allows for fairly accurate grading of dissections comparable to digital subtraction angiography, which may be helpful in clinical management [131]. The potential detractors from CTA of the neck are the requirements for iodinated contrast and ionizing radiation. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the initial imaging of suspected cervical vascular dissection or injury.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Head With IV Contrast CTA of the head may be useful in the evaluation for intracranial extension of a known cervical dissection. CTA of the head may also be useful for evaluation of intracranial collaterals of the circle of Willis and excluding associated intracranial LVO, which is important in stroke risk stratification and treatment strategies. As such, although a CTA of the head may be necessary in the workup of a known cervical artery dissection, there is no literature to support CTA of the head in the initial screening examination for a suspected cervical artery dissection. CTA Neck With IV Contrast CTA of the neck is useful in the initial screening examination for suspected cervical vascular dissection owing to rapid acquisition and high spatial resolution of the examination. Rapid examination is important in the evaluation for suspected cervical dissection due to the stroke risk associated with treatment delays. The high resolution of CTA neck allows for the detection of fairly subtle dissections with high sensitivity for both cervical carotid and vertebral artery dissections with a sensitivity and specificity approaching 98% [129]. CTA neck can rapidly and accurately grade the degree of luminal narrowing, vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap, which may make it preferable to MRA [130]. CTA neck also allows for fairly accurate grading of dissections comparable to digital subtraction angiography, which may be helpful in clinical management [131]. The potential detractors from CTA of the neck are the requirements for iodinated contrast and ionizing radiation. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the initial imaging of suspected cervical vascular dissection or injury.

3149012

acrac_3149012_56

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the initial imaging of suspected cervical vascular dissection or injury. MRA Head Without IV Contrast MRA of the head may be useful in evaluation for intracranial extension of a known cervical dissection. MRA of the head may also be useful for evaluation of intracranial collaterals of the circle of Willis, which is important in stroke risk stratification and treatment strategies. As such, although an MRA of the head may be useful in the workup of a known cervical dissection, there is no literature to support MRA of the head in the initial imaging of suspected cervical arterial dissection. MRA Neck Without and With IV Contrast MRA of the neck is useful in the initial screening examination for suspected cervical vascular dissection owing to high tissue contrast, especially incorporating fat-saturated T1-weighted sequences, which may be helpful in delineation of subtle intramural hematomas improving visibility to the examiner. The sensitivity of MRI neck is similar to CTA neck for cervical carotid dissections. However, the sensitivity for detection of cervical vertebral artery dissections is significantly reduced compared with CTA neck to as low as 60%, with some variability depending on the technique and sequences employed [129]. Limitations of MRA neck include longer acquisition times and lower spatial resolution, which may delay care or miss subtle intimal irregularities associated with suspected cervical vascular dissections, particularly those involving the vertebral artery. Additionally, an Cerebrovascular Diseases-Stroke unenhanced MRA of the neck may also overestimate the degree of stenosis in more severe dissections, and the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the initial imaging of suspected cervical vascular dissection or injury. MRA Head Without IV Contrast MRA of the head may be useful in evaluation for intracranial extension of a known cervical dissection. MRA of the head may also be useful for evaluation of intracranial collaterals of the circle of Willis, which is important in stroke risk stratification and treatment strategies. As such, although an MRA of the head may be useful in the workup of a known cervical dissection, there is no literature to support MRA of the head in the initial imaging of suspected cervical arterial dissection. MRA Neck Without and With IV Contrast MRA of the neck is useful in the initial screening examination for suspected cervical vascular dissection owing to high tissue contrast, especially incorporating fat-saturated T1-weighted sequences, which may be helpful in delineation of subtle intramural hematomas improving visibility to the examiner. The sensitivity of MRI neck is similar to CTA neck for cervical carotid dissections. However, the sensitivity for detection of cervical vertebral artery dissections is significantly reduced compared with CTA neck to as low as 60%, with some variability depending on the technique and sequences employed [129]. Limitations of MRA neck include longer acquisition times and lower spatial resolution, which may delay care or miss subtle intimal irregularities associated with suspected cervical vascular dissections, particularly those involving the vertebral artery. Additionally, an Cerebrovascular Diseases-Stroke unenhanced MRA of the neck may also overestimate the degree of stenosis in more severe dissections, and the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used.

3149012

acrac_3149012_57

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Contrast administration can reduce the degree of overestimation of the degree of stenosis in many cases [132]. MRA Neck Without IV Contrast MRA of the neck is useful in the initial screening examination for suspected cervical vascular dissection owing to high tissue contrast, especially incorporating fat-saturated T1-weighted sequences, which may be helpful in the delineation of subtle intramural hematomas, improving visibility to the examiner. The sensitivity of MRI neck is similar to CTA neck for cervical carotid dissections. However, the sensitivity for the detection of cervical vertebral artery dissections is significantly reduced compared with CTA neck to as low as 60%, with some variability depending on the technique and sequences employed [129]. Limitations of MRA neck include longer acquisition times and lower spatial resolution, which may delay care or miss subtle intimal irregularities associated with suspected cervical vascular dissections, particularly those involving the vertebral artery. Additionally, an unenhanced MRA of the neck may also overestimate the degree of stenosis in more severe dissections, and the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used. Contrast administration can reduce the degree of overestimation of the degree of stenosis in many cases [132]. MRI Head Perfusion With IV Contrast There is no literature to support the use of MRI head perfusion as the initial imaging test in the detection of a suspected cervical artery dissection. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the initial imaging of suspected cervical vascular dissection or injury.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Contrast administration can reduce the degree of overestimation of the degree of stenosis in many cases [132]. MRA Neck Without IV Contrast MRA of the neck is useful in the initial screening examination for suspected cervical vascular dissection owing to high tissue contrast, especially incorporating fat-saturated T1-weighted sequences, which may be helpful in the delineation of subtle intramural hematomas, improving visibility to the examiner. The sensitivity of MRI neck is similar to CTA neck for cervical carotid dissections. However, the sensitivity for the detection of cervical vertebral artery dissections is significantly reduced compared with CTA neck to as low as 60%, with some variability depending on the technique and sequences employed [129]. Limitations of MRA neck include longer acquisition times and lower spatial resolution, which may delay care or miss subtle intimal irregularities associated with suspected cervical vascular dissections, particularly those involving the vertebral artery. Additionally, an unenhanced MRA of the neck may also overestimate the degree of stenosis in more severe dissections, and the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used. Contrast administration can reduce the degree of overestimation of the degree of stenosis in many cases [132]. MRI Head Perfusion With IV Contrast There is no literature to support the use of MRI head perfusion as the initial imaging test in the detection of a suspected cervical artery dissection. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the initial imaging of suspected cervical vascular dissection or injury.

3149012

acrac_3149012_58

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRI Head Without IV Contrast MRI of the head may be useful in evaluating strokes in the setting of a known dissection or in the exclusion of ICH before the initiation of anticoagulation or antiplatelet therapy for a known dissection. As such, although an MRI of the head may be useful in the workup of a known dissection, there is no literature to support an MRI of the head in the initial screening examination for a suspected cervical artery dissection. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the initial imaging of suspected cervical vascular dissection or injury. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the initial imaging of suspected cervical vascular dissection or injury. US Duplex Doppler Carotid Artery There is no literature that supports duplex Doppler examination of the carotid in the initial imaging of suspected cervical vascular dissection or injury. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in determining the hemodynamic significance of a known cervical vascular dissection. However, there is no literature to support transcranial Doppler in the initial imaging of suspected cervical vascular dissection or injury. Variant 12: Adult. Known cervical vascular dissection or injury. Surveillance imaging. Cervical cerebrovascular dissections are an important stroke etiology across all age ranges with an incidence of 2 per 100,000, accounting for 15% of all strokes [125]. The indications for neurologic imaging in the surveillance of vascular dissection vary based on the cause and severity of dissection, stability of the patient, and presence of ongoing or worsening symptoms.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRI Head Without IV Contrast MRI of the head may be useful in evaluating strokes in the setting of a known dissection or in the exclusion of ICH before the initiation of anticoagulation or antiplatelet therapy for a known dissection. As such, although an MRI of the head may be useful in the workup of a known dissection, there is no literature to support an MRI of the head in the initial screening examination for a suspected cervical artery dissection. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV of the head in the initial imaging of suspected cervical vascular dissection or injury. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV of the head in the initial imaging of suspected cervical vascular dissection or injury. US Duplex Doppler Carotid Artery There is no literature that supports duplex Doppler examination of the carotid in the initial imaging of suspected cervical vascular dissection or injury. US Duplex Doppler Transcranial Transcranial Doppler may be useful, both in the detection of microembolic events and in determining the hemodynamic significance of a known cervical vascular dissection. However, there is no literature to support transcranial Doppler in the initial imaging of suspected cervical vascular dissection or injury. Variant 12: Adult. Known cervical vascular dissection or injury. Surveillance imaging. Cervical cerebrovascular dissections are an important stroke etiology across all age ranges with an incidence of 2 per 100,000, accounting for 15% of all strokes [125]. The indications for neurologic imaging in the surveillance of vascular dissection vary based on the cause and severity of dissection, stability of the patient, and presence of ongoing or worsening symptoms.

3149012

acrac_3149012_59

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Cerebrovascular dissections associated with major nonpenetrating trauma are typically graded on the Biffl scale, which is in most cases colloquially referred to as the Denver grading scale. Higher-grade dissections are more likely to result in ischemic complications [126]. For these dissections associated with major nonpenetrating trauma, repeat imaging with CTA neck is recommend at 7 days and again at 3 months [133]. For patients with minor or no trauma, outcome is not correlated with the degree of subsequent recanalization Cerebrovascular Diseases-Stroke so a role of follow-up imaging has not been established [134-136]. The subsequent surveillance imaging of cervical vascular dissections centers on the evaluation of healing of the dissection, risk stratification, and development for ongoing ischemic and hemorrhagic complications. Surveillance imaging is less focused on screening for intracranial complication of known dissection beyond the early stages of vascular injury. For indicated imaging in patients with focal neurological deficits relative to cervicocerebral dissections, please see Variants 1 to 5 for additional indicated imaging procedures. Dissection may also be the result of suspected connective tissue disorder, which may also warrant further imaging workup. Arteriography Cervicocerebral Catheter-directed cerebral angiography may be useful in the surveillance imaging of some selected cases of known vascular dissection. Specifically, assessment for complete healing of a previously symptomatic dissection or assessment of progression of a known dissection with new or ongoing focal neurological symptom may be more completely assessed by catheter-directed angiography owing to higher spatial and temporal resolution compared with other vascular studies.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Cerebrovascular dissections associated with major nonpenetrating trauma are typically graded on the Biffl scale, which is in most cases colloquially referred to as the Denver grading scale. Higher-grade dissections are more likely to result in ischemic complications [126]. For these dissections associated with major nonpenetrating trauma, repeat imaging with CTA neck is recommend at 7 days and again at 3 months [133]. For patients with minor or no trauma, outcome is not correlated with the degree of subsequent recanalization Cerebrovascular Diseases-Stroke so a role of follow-up imaging has not been established [134-136]. The subsequent surveillance imaging of cervical vascular dissections centers on the evaluation of healing of the dissection, risk stratification, and development for ongoing ischemic and hemorrhagic complications. Surveillance imaging is less focused on screening for intracranial complication of known dissection beyond the early stages of vascular injury. For indicated imaging in patients with focal neurological deficits relative to cervicocerebral dissections, please see Variants 1 to 5 for additional indicated imaging procedures. Dissection may also be the result of suspected connective tissue disorder, which may also warrant further imaging workup. Arteriography Cervicocerebral Catheter-directed cerebral angiography may be useful in the surveillance imaging of some selected cases of known vascular dissection. Specifically, assessment for complete healing of a previously symptomatic dissection or assessment of progression of a known dissection with new or ongoing focal neurological symptom may be more completely assessed by catheter-directed angiography owing to higher spatial and temporal resolution compared with other vascular studies.

3149012

acrac_3149012_60

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CT Head Perfusion With IV Contrast For indicated imaging in patients with focal neurological deficits relative to cervicocerebral cervical dissections, please see Variants 1 to 5 for additional indicated imaging procedures. However, there is no literature to support the use of CTP as a routine surveillance imaging test in the ongoing evaluation of cervical artery dissections. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the surveillance imaging of cervical vascular dissection. CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the surveillance imaging of cervical vascular dissection. CT Head Without IV Contrast In the absence of ongoing symptoms, there is no literature to support routine surveillance imaging of the brain parenchyma in the setting of cervical vascular dissection. Noncontrast CT may be useful in the setting of a known dissection in the patient with ongoing or new symptoms to evaluate for new ischemic stroke and complications such as hemorrhagic conversion, mass effect, and herniation or in the exclusion of ICH in the setting of ongoing medical treatment of vascular dissections. However, MRI is much more sensitive in evaluating recent strokes. CTA Head With IV Contrast There is no literature to support CTA of the head in the routine surveillance of known dissections isolated to the cervical vasculature. CTA of the head may be useful in the surveillance of cervical vascular dissections that are known to extend into the intracranial vasculature. CTA of the head may also be useful for the evaluation of intracranial collaterals of the circle of Willis and excluding associated intracranial LVO in patients with ongoing symptoms, which is important in stroke risk stratification and treatment strategies.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CT Head Perfusion With IV Contrast For indicated imaging in patients with focal neurological deficits relative to cervicocerebral cervical dissections, please see Variants 1 to 5 for additional indicated imaging procedures. However, there is no literature to support the use of CTP as a routine surveillance imaging test in the ongoing evaluation of cervical artery dissections. CT Head With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the surveillance imaging of cervical vascular dissection. CT Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced CT of the head in the surveillance imaging of cervical vascular dissection. CT Head Without IV Contrast In the absence of ongoing symptoms, there is no literature to support routine surveillance imaging of the brain parenchyma in the setting of cervical vascular dissection. Noncontrast CT may be useful in the setting of a known dissection in the patient with ongoing or new symptoms to evaluate for new ischemic stroke and complications such as hemorrhagic conversion, mass effect, and herniation or in the exclusion of ICH in the setting of ongoing medical treatment of vascular dissections. However, MRI is much more sensitive in evaluating recent strokes. CTA Head With IV Contrast There is no literature to support CTA of the head in the routine surveillance of known dissections isolated to the cervical vasculature. CTA of the head may be useful in the surveillance of cervical vascular dissections that are known to extend into the intracranial vasculature. CTA of the head may also be useful for the evaluation of intracranial collaterals of the circle of Willis and excluding associated intracranial LVO in patients with ongoing symptoms, which is important in stroke risk stratification and treatment strategies.

3149012

acrac_3149012_61

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

CTA Neck With IV Contrast CTA of the neck is useful in ongoing surveillance imaging of cervical vascular dissection owing to high spatial resolution of the examination. The high resolution of CTA allows for the detection of subtle dissections with high sensitivity for both cervical carotid and vertebral artery dissections with a sensitivity and specificity approaching 98%, which informs the usefulness of CTA in follow-up surveillance imaging [129]. CTA can rapidly and accurately grade the degree of luminal narrowing, vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap, which may make it preferable to MRA [130]. CTA also allows for accurate grading of dissections comparable to digital subtraction angiography, which may be helpful in clinical management [131]. The potential detractors from CTA of the neck are the requirements for iodinated contrast and ionizing radiation. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the surveillance imaging of cervical vascular dissection. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the surveillance imaging of cervical vascular dissection. Cerebrovascular Diseases-Stroke MRA Head Without IV Contrast There is no literature to support MRA of the head in the routine surveillance of known dissections isolated to the cervical vasculature. MRA of the head may be useful in the surveillance of cervical vascular dissections that are known to extend into the intracranial vasculature. MRA of the head may also be useful for the evaluation of intracranial collaterals of the circle of Willis and excluding associated intracranial LVO in patients with ongoing symptoms, which is important in stroke risk stratification and treatment strategies.

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. CTA Neck With IV Contrast CTA of the neck is useful in ongoing surveillance imaging of cervical vascular dissection owing to high spatial resolution of the examination. The high resolution of CTA allows for the detection of subtle dissections with high sensitivity for both cervical carotid and vertebral artery dissections with a sensitivity and specificity approaching 98%, which informs the usefulness of CTA in follow-up surveillance imaging [129]. CTA can rapidly and accurately grade the degree of luminal narrowing, vessel irregularity, wall thickening/hematoma, pseudoaneurysm, and intimal flap, which may make it preferable to MRA [130]. CTA also allows for accurate grading of dissections comparable to digital subtraction angiography, which may be helpful in clinical management [131]. The potential detractors from CTA of the neck are the requirements for iodinated contrast and ionizing radiation. CTV Head With IV Contrast There is no relevant literature to support the use of CTV of the head in the surveillance imaging of cervical vascular dissection. MRA Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRA of the head in the surveillance imaging of cervical vascular dissection. Cerebrovascular Diseases-Stroke MRA Head Without IV Contrast There is no literature to support MRA of the head in the routine surveillance of known dissections isolated to the cervical vasculature. MRA of the head may be useful in the surveillance of cervical vascular dissections that are known to extend into the intracranial vasculature. MRA of the head may also be useful for the evaluation of intracranial collaterals of the circle of Willis and excluding associated intracranial LVO in patients with ongoing symptoms, which is important in stroke risk stratification and treatment strategies.

3149012

acrac_3149012_62

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

MRA Neck Without and With IV Contrast MRA of the neck may be useful in the surveillance imaging of known cervical vascular dissections owing to high tissue contrast, especially incorporating fat-saturated T1-weighted sequences, which may better demonstrate subtler intramural hematomas that may not be visible on other noninvasive studies. However, some dissections may be too subtle to follow by MRA of the neck due to lower spatial resolution compared with CTA. Specifically, the sensitivity of MRI is similar to CTA for cervical carotid dissections; however, the sensitivity for the detection of cervical vertebral artery dissections is significantly reduced compared with CTA to as low as 60% with some variability depending on the technique and sequences employed [129]. Unenhanced MRA of the neck may also overestimate the degree of stenosis in more severe dissections, and the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used. Contrast administration can reduce the degree of overestimation of the degree of stenosis in many cases [132]. MRA Neck Without IV Contrast MRA of the neck may be useful in the surveillance imaging of known cervical vascular dissections owing to high tissue contrast, especially incorporating fat-saturated T1-weighted sequences, which may better demonstrate subtler intramural hematomas that may not be visible on other noninvasive studies. However, some dissections may be too subtle to follow by MRA of the neck due to lower spatial resolution compared with CTA. Specifically, the sensitivity of MRI is similar to CTA for cervical carotid dissections; however, the sensitivity for detection of cervical vertebral artery dissections is significantly reduced compared with CTA to as low as 60% with some variability depending on the technique and sequences employed [129].

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. MRA Neck Without and With IV Contrast MRA of the neck may be useful in the surveillance imaging of known cervical vascular dissections owing to high tissue contrast, especially incorporating fat-saturated T1-weighted sequences, which may better demonstrate subtler intramural hematomas that may not be visible on other noninvasive studies. However, some dissections may be too subtle to follow by MRA of the neck due to lower spatial resolution compared with CTA. Specifically, the sensitivity of MRI is similar to CTA for cervical carotid dissections; however, the sensitivity for the detection of cervical vertebral artery dissections is significantly reduced compared with CTA to as low as 60% with some variability depending on the technique and sequences employed [129]. Unenhanced MRA of the neck may also overestimate the degree of stenosis in more severe dissections, and the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used. Contrast administration can reduce the degree of overestimation of the degree of stenosis in many cases [132]. MRA Neck Without IV Contrast MRA of the neck may be useful in the surveillance imaging of known cervical vascular dissections owing to high tissue contrast, especially incorporating fat-saturated T1-weighted sequences, which may better demonstrate subtler intramural hematomas that may not be visible on other noninvasive studies. However, some dissections may be too subtle to follow by MRA of the neck due to lower spatial resolution compared with CTA. Specifically, the sensitivity of MRI is similar to CTA for cervical carotid dissections; however, the sensitivity for detection of cervical vertebral artery dissections is significantly reduced compared with CTA to as low as 60% with some variability depending on the technique and sequences employed [129].

3149012

acrac_3149012_63

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs

Unenhanced MRA of the neck may also overestimate the degree of stenosis in more severe dissections, and the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used. Contrast administration can reduce the degree of overestimation of the degree of stenosis in many cases [132]. MRI Head Perfusion With IV Contrast There is no literature to support the use of MRI head perfusion in the surveillance imaging of cervical vascular dissection. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the surveillance imaging of cervical vascular dissection. MRI Head Without IV Contrast There is no literature to support an MRI of the head in the surveillance imaging of cervical vascular dissection. MRI of the head may be useful in the setting of a known dissection in the patient with ongoing or new symptoms to evaluate for new ischemic stroke and complications such as hemorrhagic conversion, mass effect, and herniation or in the exclusion of ICH in the setting of ongoing medical treatment of vascular dissections. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV head in the surveillance imaging of cervical vascular dissection. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV head in the surveillance imaging of cervical vascular dissection. US Duplex Doppler Carotid Artery Limited studies have used US in follow-up of known cervical carotid dissection [137]. There is no relevant literature to support the use of US duplex Doppler examination of the carotid in the surveillance imaging of cervical vascular dissection. Cerebrovascular Diseases-Stroke

Cerebrovascular Diseases Stroke and Stroke Related Conditions PCAs. Unenhanced MRA of the neck may also overestimate the degree of stenosis in more severe dissections, and the anatomic definition of the surrounding structures may be inadequate for treatment planning in some cases depending on the sequences used. Contrast administration can reduce the degree of overestimation of the degree of stenosis in many cases [132]. MRI Head Perfusion With IV Contrast There is no literature to support the use of MRI head perfusion in the surveillance imaging of cervical vascular dissection. MRI Head Without and With IV Contrast There is no relevant literature to support the use of contrast-enhanced MRI of the head in the surveillance imaging of cervical vascular dissection. MRI Head Without IV Contrast There is no literature to support an MRI of the head in the surveillance imaging of cervical vascular dissection. MRI of the head may be useful in the setting of a known dissection in the patient with ongoing or new symptoms to evaluate for new ischemic stroke and complications such as hemorrhagic conversion, mass effect, and herniation or in the exclusion of ICH in the setting of ongoing medical treatment of vascular dissections. MRV Head Without and With IV Contrast There is no relevant literature to support the use of MRV head in the surveillance imaging of cervical vascular dissection. MRV Head Without IV Contrast There is no relevant literature to support the use of MRV head in the surveillance imaging of cervical vascular dissection. US Duplex Doppler Carotid Artery Limited studies have used US in follow-up of known cervical carotid dissection [137]. There is no relevant literature to support the use of US duplex Doppler examination of the carotid in the surveillance imaging of cervical vascular dissection. Cerebrovascular Diseases-Stroke

3149012

acrac_69492_0

Renal Failure

AKI is common, affecting up to 20% of hospital inpatients and between 30% to 60% of critically ill patients [3] with a rising incidence worldwide. Hospital-acquired AKI is 5 to 10 times more common than community-acquired AKI. AKI has a significant impact on patient morbidity and mortality with increased health care costs. AKI may be reversible or can lead to CKD. AKI is often multifactorial but generally categorized as prerenal, renal, or postrenal. Prerenal factors include impaired blood flow from any cause including hypotension, hypovolemia, decreased cardiac output, or renal artery occlusion. Renal causes include any disease that damages renal parenchyma, such as vasculitis, acute tubular necrosis, glomerulonephritis, interstitial nephritis, renal infection or infiltration, drugs, and toxins. Postrenal AKI results from ureteral, bladder, or urethral obstruction. Renal and prerenal etiologies far outweigh obstruction as a cause of AKI, accounting for >97% of AKI [4]. For appropriate intervention, identification of the specific cause of AKI is critical, as there are different treatments for diseases such as glomerulonephritis, vasculitis, and ureteral obstruction. Evaluation of the patient with AKI includes a thorough history, physical examination, and laboratory analysis of blood (for serum creatinine, blood urea nitrogen, complete blood count, and differential) and urine (microscopy for casts and epithelial cells, chemistry, and biomarkers) [3]. Renal biopsy may be indicated for differentiation of nephritic and nephrotic syndromes [3]. CKD is common, affecting 10% of the world population. It is defined as an abnormality of kidney structure or function, present for >3 months, with health consequences [5]. The definition requires knowledge of laboratory values in the preceding 3 months. Hypertension and diabetes are the predominant risk factors for CKD [6].

Renal Failure. AKI is common, affecting up to 20% of hospital inpatients and between 30% to 60% of critically ill patients [3] with a rising incidence worldwide. Hospital-acquired AKI is 5 to 10 times more common than community-acquired AKI. AKI has a significant impact on patient morbidity and mortality with increased health care costs. AKI may be reversible or can lead to CKD. AKI is often multifactorial but generally categorized as prerenal, renal, or postrenal. Prerenal factors include impaired blood flow from any cause including hypotension, hypovolemia, decreased cardiac output, or renal artery occlusion. Renal causes include any disease that damages renal parenchyma, such as vasculitis, acute tubular necrosis, glomerulonephritis, interstitial nephritis, renal infection or infiltration, drugs, and toxins. Postrenal AKI results from ureteral, bladder, or urethral obstruction. Renal and prerenal etiologies far outweigh obstruction as a cause of AKI, accounting for >97% of AKI [4]. For appropriate intervention, identification of the specific cause of AKI is critical, as there are different treatments for diseases such as glomerulonephritis, vasculitis, and ureteral obstruction. Evaluation of the patient with AKI includes a thorough history, physical examination, and laboratory analysis of blood (for serum creatinine, blood urea nitrogen, complete blood count, and differential) and urine (microscopy for casts and epithelial cells, chemistry, and biomarkers) [3]. Renal biopsy may be indicated for differentiation of nephritic and nephrotic syndromes [3]. CKD is common, affecting 10% of the world population. It is defined as an abnormality of kidney structure or function, present for >3 months, with health consequences [5]. The definition requires knowledge of laboratory values in the preceding 3 months. Hypertension and diabetes are the predominant risk factors for CKD [6].

69492

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Renal Failure

Five stages of CKD are based on estimated GFR calculated using serum creatinine and standard equations such as the Modification of Diet in Renal Disease study equation or CKD Epidemiology Collaboration equation [7]. Stage 5 with a GFR <15 mL/min per 1.73 m2 body surface area is considered kidney failure [5]. CKD may be silent, progressing through stages of CKD to renal failure. Patients with CKD are at increased risk for hypertension, cardiovascular disease, bone disease, and anemia with increased morbidity and mortality. Evaluation of the patient with CKD will include a thorough history, physical examination, laboratory, and serologic workups. Markers of kidney damage include measurement of albuminuria and urinary sediment; urinary albumin- aUniversity of Maryland School of Medicine, Baltimore, Maryland. bPanel Chair, Northwestern University, Chicago, Illinois. cPanel Vice-Chair, UT Southwestern Medical Center, Dallas, Texas. dUniversity of Rochester Medical Center, Rochester, New York. eThe University of Texas MD Anderson Cancer Center, Houston, Texas. fUniversity of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; American Society of Nephrology. gUniversity of Washington, Seattle, Washington; American Urological Association. hDuke University Medical Center, Durham, North Carolina. iEmory University School of Medicine, Atlanta, Georgia. jThomas Jefferson University Hospital, Philadelphia, Pennsylvania. kUT Health San Antonio, San Antonio, Texas. lCleveland Clinic, Cleveland, Ohio. mMedical University of South Carolina, Charleston, South Carolina; American Urological Association. nUniversity of Alabama at Birmingham, Birmingham, Alabama. oUniversity of California San Francisco School of Medicine, San Francisco, California. pJohns Hopkins University School of Medicine, Washington, District of Columbia. qSpecialty Chair, University of Alabama at Birmingham, Birmingham, Alabama.

Renal Failure. Five stages of CKD are based on estimated GFR calculated using serum creatinine and standard equations such as the Modification of Diet in Renal Disease study equation or CKD Epidemiology Collaboration equation [7]. Stage 5 with a GFR <15 mL/min per 1.73 m2 body surface area is considered kidney failure [5]. CKD may be silent, progressing through stages of CKD to renal failure. Patients with CKD are at increased risk for hypertension, cardiovascular disease, bone disease, and anemia with increased morbidity and mortality. Evaluation of the patient with CKD will include a thorough history, physical examination, laboratory, and serologic workups. Markers of kidney damage include measurement of albuminuria and urinary sediment; urinary albumin- aUniversity of Maryland School of Medicine, Baltimore, Maryland. bPanel Chair, Northwestern University, Chicago, Illinois. cPanel Vice-Chair, UT Southwestern Medical Center, Dallas, Texas. dUniversity of Rochester Medical Center, Rochester, New York. eThe University of Texas MD Anderson Cancer Center, Houston, Texas. fUniversity of Pennsylvania School of Medicine, Philadelphia, Pennsylvania; American Society of Nephrology. gUniversity of Washington, Seattle, Washington; American Urological Association. hDuke University Medical Center, Durham, North Carolina. iEmory University School of Medicine, Atlanta, Georgia. jThomas Jefferson University Hospital, Philadelphia, Pennsylvania. kUT Health San Antonio, San Antonio, Texas. lCleveland Clinic, Cleveland, Ohio. mMedical University of South Carolina, Charleston, South Carolina; American Urological Association. nUniversity of Alabama at Birmingham, Birmingham, Alabama. oUniversity of California San Francisco School of Medicine, San Francisco, California. pJohns Hopkins University School of Medicine, Washington, District of Columbia. qSpecialty Chair, University of Alabama at Birmingham, Birmingham, Alabama.

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Renal Failure

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] Renal Failure to-creatinine ratio is a sensitive and specific marker for CKD. Abnormal histology on kidney biopsy or structural abnormalities on imaging (small echogenic kidneys, dysplastic or polycystic kidneys, renal scarring, hydronephrosis) will also qualify as CKD [8]. Special Imaging Considerations The use of iodinated contrast or gadolinium-based contrast agents merits special discussion in the context of renal failure. Generally, iodinated contrast is avoided in AKI unless there is an over-riding clinical question that cannot be answered with an alternative imaging modality or when an intravascular intervention is required [9]. Avoidance of other nephrotoxic drugs, adequate hydration, and close assessment are part of the management. In CKD, the risk- benefit ratio is determined by the level and acuity of kidney disease, specifically weighing the benefits versus risks of any contrast agent. Patients already on hemodialysis or peritoneal dialysis may undergo contrast-enhanced CT if there is no residual renal function. For MRI, there are risk-benefit considerations with respect to the type of gadolinium-based contrast agents. Unenhanced MR angiography (MRA) techniques may be diagnostic. Group II gadolinium-based contrast agents, and lowest diagnostic contrast dose should be standard for contrast-enhanced MRA. Patients already on hemodialysis may undergo contrast-enhanced MRI with group II agents if safety guidelines are followed. For more details please refer to the ACR Manual on Contrast Media [9].

Renal Failure. 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] Renal Failure to-creatinine ratio is a sensitive and specific marker for CKD. Abnormal histology on kidney biopsy or structural abnormalities on imaging (small echogenic kidneys, dysplastic or polycystic kidneys, renal scarring, hydronephrosis) will also qualify as CKD [8]. Special Imaging Considerations The use of iodinated contrast or gadolinium-based contrast agents merits special discussion in the context of renal failure. Generally, iodinated contrast is avoided in AKI unless there is an over-riding clinical question that cannot be answered with an alternative imaging modality or when an intravascular intervention is required [9]. Avoidance of other nephrotoxic drugs, adequate hydration, and close assessment are part of the management. In CKD, the risk- benefit ratio is determined by the level and acuity of kidney disease, specifically weighing the benefits versus risks of any contrast agent. Patients already on hemodialysis or peritoneal dialysis may undergo contrast-enhanced CT if there is no residual renal function. For MRI, there are risk-benefit considerations with respect to the type of gadolinium-based contrast agents. Unenhanced MR angiography (MRA) techniques may be diagnostic. Group II gadolinium-based contrast agents, and lowest diagnostic contrast dose should be standard for contrast-enhanced MRA. Patients already on hemodialysis may undergo contrast-enhanced MRI with group II agents if safety guidelines are followed. For more details please refer to the ACR Manual on Contrast Media [9].

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Ultrasound (US) contrast media are not nephrotoxic, which makes these potentially ideal agents for microvascular imaging in AKI or CKD [10]. Contrast-enhanced US has the potential to provide dynamic quantitative information about renal perfusion and can diagnose acute cortical necrosis and infarction in allografts and native kidneys [11- 13]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/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. CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Oral hydration, IV saline hydration, compression bands, and low- dose furosemide have all been reported as methods to improve urinary distension. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system.

Renal Failure. Ultrasound (US) contrast media are not nephrotoxic, which makes these potentially ideal agents for microvascular imaging in AKI or CKD [10]. Contrast-enhanced US has the potential to provide dynamic quantitative information about renal perfusion and can diagnose acute cortical necrosis and infarction in allografts and native kidneys [11- 13]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/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. CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Oral hydration, IV saline hydration, compression bands, and low- dose furosemide have all been reported as methods to improve urinary distension. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system.

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Renal Failure

Unenhanced MRU relies upon heavily T2-weighted imaging of the intrinsic high signal from urine for evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. Contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phase. Thin-slice acquisition and multiplanar imaging should be obtained. MRU is most commonly performed on a 1.5T machine, but imaging at 3T has become more widely used; however, comparison of 3T MRU and CTU has not been published in the literature. For the purposes of this document, we make a distinction between MRU and MR abdomen and pelvis without and with IV contrast. MR abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases and without heavily T2-weighted images of the urinary tract. Renal Failure OR Discussion of Procedures by Variant Variant 1: Renal failure. Acute kidney injury (AKI), unspecified. Initial imaging. Arteriography Kidney Arteriography is reserved for intervention rather than for the initial diagnosis of AKI. Renal revascularization may be considered in a very select group of patients with AKI. There is no relevant literature regarding the use of arteriography in the evaluation of AKI. CT Abdomen and Pelvis Unenhanced CT abdomen and pelvis is useful for further evaluation of US-detected hydronephrosis by determining level and cause of obstruction. CT is the most sensitive modality for urinary tract calculi and more sensitive than US for retroperitoneal pathology [15]. Although CT can also provide an assessment of renal size and volume, it is generally not considered the first-line imaging modality for AKI [16]. CT may be considered if US is not feasible or is nondiagnostic because body habitus.

Renal Failure. Unenhanced MRU relies upon heavily T2-weighted imaging of the intrinsic high signal from urine for evaluation of the urinary tract. IV contrast is administered to provide additional information regarding obstruction, urothelial thickening, focal lesions, and stones. Contrast-enhanced T1-weighted series should include corticomedullary, nephrographic, and excretory phase. Thin-slice acquisition and multiplanar imaging should be obtained. MRU is most commonly performed on a 1.5T machine, but imaging at 3T has become more widely used; however, comparison of 3T MRU and CTU has not been published in the literature. For the purposes of this document, we make a distinction between MRU and MR abdomen and pelvis without and with IV contrast. MR abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts, without both the precontrast and excretory phases and without heavily T2-weighted images of the urinary tract. Renal Failure OR Discussion of Procedures by Variant Variant 1: Renal failure. Acute kidney injury (AKI), unspecified. Initial imaging. Arteriography Kidney Arteriography is reserved for intervention rather than for the initial diagnosis of AKI. Renal revascularization may be considered in a very select group of patients with AKI. There is no relevant literature regarding the use of arteriography in the evaluation of AKI. CT Abdomen and Pelvis Unenhanced CT abdomen and pelvis is useful for further evaluation of US-detected hydronephrosis by determining level and cause of obstruction. CT is the most sensitive modality for urinary tract calculi and more sensitive than US for retroperitoneal pathology [15]. Although CT can also provide an assessment of renal size and volume, it is generally not considered the first-line imaging modality for AKI [16]. CT may be considered if US is not feasible or is nondiagnostic because body habitus.

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Renal Failure

The use of iodinated contrast hinges on renal function and specific indication. CT with IV contrast is not appropriate for the diagnosis of and determination of the cause of AKI. There is no relevant literature regarding the use of CT abdomen and pelvis with IV contrast in the evaluation of AKI. CT abdomen and pelvis without and with IV contrast is not appropriate for the diagnosis of and determination of the cause of AKI. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast in the evaluation of AKI. CT Abdomen There is no relevant literature regarding the use of CT abdomen in the evaluation of AKI. CTA Abdomen and Pelvis Contrast-enhanced CTA is very rarely indicated for initial diagnosis of AKI given the potential nephrotoxicity. The risk-benefit ratio should be carefully evaluated if CTA is necessary to diagnose vascular thrombosis or stenosis. The lowest dose of contrast needed for a diagnostic study should be used and supplemented with adequate volume expansion [9]. There is no relevant literature regarding the use of CTA in the evaluation of AKI. CTU There is no relevant literature regarding the use of CTU in the evaluation of AKI. The requirement for IV contrast limits its utility. MRA Abdomen MRA may be considered when there is a high suspicion of a renovascular cause of AKI such as renal artery stenosis, thrombosis, or arterial injury after trauma, all of which are rare [4,17]. However, there is no relevant literature regarding the use of MRA abdomen without and with IV contrast in the evaluation of AKI. If contrast-enhanced MRA is needed after consideration of the risks and benefits, group II contrast agents should be used [9]. Contrast-enhanced MRA has a sensitivity of 93% and a specificity of 93% compared with 85% and 84%, respectively, for Doppler US for diagnosis of >60% stenosis [18]. Unenhanced MRA techniques, such as time-spatial labeling inversion pulse or steady-state free precession, may be considered in AKI.

Renal Failure. The use of iodinated contrast hinges on renal function and specific indication. CT with IV contrast is not appropriate for the diagnosis of and determination of the cause of AKI. There is no relevant literature regarding the use of CT abdomen and pelvis with IV contrast in the evaluation of AKI. CT abdomen and pelvis without and with IV contrast is not appropriate for the diagnosis of and determination of the cause of AKI. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast in the evaluation of AKI. CT Abdomen There is no relevant literature regarding the use of CT abdomen in the evaluation of AKI. CTA Abdomen and Pelvis Contrast-enhanced CTA is very rarely indicated for initial diagnosis of AKI given the potential nephrotoxicity. The risk-benefit ratio should be carefully evaluated if CTA is necessary to diagnose vascular thrombosis or stenosis. The lowest dose of contrast needed for a diagnostic study should be used and supplemented with adequate volume expansion [9]. There is no relevant literature regarding the use of CTA in the evaluation of AKI. CTU There is no relevant literature regarding the use of CTU in the evaluation of AKI. The requirement for IV contrast limits its utility. MRA Abdomen MRA may be considered when there is a high suspicion of a renovascular cause of AKI such as renal artery stenosis, thrombosis, or arterial injury after trauma, all of which are rare [4,17]. However, there is no relevant literature regarding the use of MRA abdomen without and with IV contrast in the evaluation of AKI. If contrast-enhanced MRA is needed after consideration of the risks and benefits, group II contrast agents should be used [9]. Contrast-enhanced MRA has a sensitivity of 93% and a specificity of 93% compared with 85% and 84%, respectively, for Doppler US for diagnosis of >60% stenosis [18]. Unenhanced MRA techniques, such as time-spatial labeling inversion pulse or steady-state free precession, may be considered in AKI.

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Renal Failure

These techniques have a sensitivity of 73% to 100%, specificity of 82% to 99%, and negative predictive value of 88% to 100% for the diagnosis of >50% renal artery stenosis [19,20]. Renal Failure MRI Abdomen and Pelvis MRI with IV contrast is generally not indicated in AKI. Unenhanced MRI may be used to evaluate extent and cause of suspected distal urinary tract obstruction. However, there is no relevant literature regarding the use of MRI abdomen and pelvis without IV contrast in the evaluation of AKI. There is no relevant literature regarding the use of MRI abdomen and pelvis without and with IV contrast in the evaluation of AKI. MRI with IV contrast is generally no t indicated in AKI. However, acute cortical necrosis can be specifically diagnosed when there is a low T2 signal rim at the corticomedullary junction and absence of cortical enhancement [23]. MR Urography There is no relevant literature regarding the use of MRU in the evaluation of AKI. However, a nonenhanced contrast MRU may provide additional information in patients with renal failure secondary to obstruction. Radiography Abdomen and Pelvis There is no role for radiography in AKI, other than for evaluation of renal stone disease, which acknowledges that radiography is less sensitive than CT for stone disease [24]. DMSA Renal Scan Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy is ideal for functional renal cortical imaging and is most useful for detection of focal renal parenchymal abnormalities and scars in the setting of acute or chronic pyelonephritis or for differential renal function. There is no relevant literature regarding its use in the evaluation of AKI. MAG3 Renal Scan Tc-99m mercaptoacetyltriglycine (MAG3) is the most frequently used renal tubular agent, specifically to quantify renal tubular extraction. Its rate of clearance can be used as an independent measure of renal function.

Renal Failure. These techniques have a sensitivity of 73% to 100%, specificity of 82% to 99%, and negative predictive value of 88% to 100% for the diagnosis of >50% renal artery stenosis [19,20]. Renal Failure MRI Abdomen and Pelvis MRI with IV contrast is generally not indicated in AKI. Unenhanced MRI may be used to evaluate extent and cause of suspected distal urinary tract obstruction. However, there is no relevant literature regarding the use of MRI abdomen and pelvis without IV contrast in the evaluation of AKI. There is no relevant literature regarding the use of MRI abdomen and pelvis without and with IV contrast in the evaluation of AKI. MRI with IV contrast is generally no t indicated in AKI. However, acute cortical necrosis can be specifically diagnosed when there is a low T2 signal rim at the corticomedullary junction and absence of cortical enhancement [23]. MR Urography There is no relevant literature regarding the use of MRU in the evaluation of AKI. However, a nonenhanced contrast MRU may provide additional information in patients with renal failure secondary to obstruction. Radiography Abdomen and Pelvis There is no role for radiography in AKI, other than for evaluation of renal stone disease, which acknowledges that radiography is less sensitive than CT for stone disease [24]. DMSA Renal Scan Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy is ideal for functional renal cortical imaging and is most useful for detection of focal renal parenchymal abnormalities and scars in the setting of acute or chronic pyelonephritis or for differential renal function. There is no relevant literature regarding its use in the evaluation of AKI. MAG3 Renal Scan Tc-99m mercaptoacetyltriglycine (MAG3) is the most frequently used renal tubular agent, specifically to quantify renal tubular extraction. Its rate of clearance can be used as an independent measure of renal function.

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Renal Failure

The Tc-99m MAG3 radionuclide angiogram assesses renal perfusion, and the following scintigraphic renogram can quantity split renal function. Diuretic furosemide renography can help to confirm a dilated obstructed versus a dilated nonobstructed renal collecting system. A persistent nephrogram without excretion suggests acute tubular necrosis [25]. Measurement of effective renal plasma flow may provide prognostic information. However, Tc-99m MAG3 is not widely used in the differentiation of causes of AKI. US Kidneys Retroperitoneum US has the greatest diagnostic value in the detection of hydronephrosis associated with acute urinary tract obstruction [4]. Grayscale US is highly sensitive (>90%) for hydronephrosis and bladder distension, allowing localization of the level of obstruction and guiding intervention such as Foley catheter placement or nephrostomy/stenting [26]. However, even in hospitalized patients with AKI, the prevalence of hydronephrosis is low, ranging from 5% to 10%, with obstruction being the cause of AKI in <45.2% of patients with hydronephrosis [4,27-29]. The highest yield for US is in patients with risk factors for urinary obstruction, such as pelvic tumors, bladder disorders, prostate hypertrophy, stone disease, and pelvic surgery. In patients without risk factors for obstruction, <1% of patients had US-detected obstruction [4]. Hydronephrosis does not necessarily indicate obstruction; a distended bladder, reflux, pregnancy, postobstructive dilation, or diuresis may cause ureteral and collecting system dilatation. When the bladder is distended, the patient should be re-evaluated after the bladder has been decompressed by voiding or catheterization. False-negative US studies may be secondary to suboptimal image quality, dehydration, early obstruction, or compression of the renal pelvis or ureters by tumor or fibrosis. A secondary role of US is the evaluation of renal size, echogenicity, and morphology to differentiate AKI from CKD and allow determination of prognosis.

Renal Failure. The Tc-99m MAG3 radionuclide angiogram assesses renal perfusion, and the following scintigraphic renogram can quantity split renal function. Diuretic furosemide renography can help to confirm a dilated obstructed versus a dilated nonobstructed renal collecting system. A persistent nephrogram without excretion suggests acute tubular necrosis [25]. Measurement of effective renal plasma flow may provide prognostic information. However, Tc-99m MAG3 is not widely used in the differentiation of causes of AKI. US Kidneys Retroperitoneum US has the greatest diagnostic value in the detection of hydronephrosis associated with acute urinary tract obstruction [4]. Grayscale US is highly sensitive (>90%) for hydronephrosis and bladder distension, allowing localization of the level of obstruction and guiding intervention such as Foley catheter placement or nephrostomy/stenting [26]. However, even in hospitalized patients with AKI, the prevalence of hydronephrosis is low, ranging from 5% to 10%, with obstruction being the cause of AKI in <45.2% of patients with hydronephrosis [4,27-29]. The highest yield for US is in patients with risk factors for urinary obstruction, such as pelvic tumors, bladder disorders, prostate hypertrophy, stone disease, and pelvic surgery. In patients without risk factors for obstruction, <1% of patients had US-detected obstruction [4]. Hydronephrosis does not necessarily indicate obstruction; a distended bladder, reflux, pregnancy, postobstructive dilation, or diuresis may cause ureteral and collecting system dilatation. When the bladder is distended, the patient should be re-evaluated after the bladder has been decompressed by voiding or catheterization. False-negative US studies may be secondary to suboptimal image quality, dehydration, early obstruction, or compression of the renal pelvis or ureters by tumor or fibrosis. A secondary role of US is the evaluation of renal size, echogenicity, and morphology to differentiate AKI from CKD and allow determination of prognosis.

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Renal Failure

Normal renal length is >10 cm in the third decade, but renal length correlates with height, sex, age (negative correlation), and weight in normal patients and varies with the state of hydration or presence of an obstruction [3]. Renal size/volume correlates with creatinine clearance [30]. Both kidney Renal Failure size and parenchymal thickness decrease in CKD [31]. Therefore, a normal kidney size suggests AKI rather than CKD. However, infiltrative and inflammatory diseases, as well as renal vein thrombosis, may increase kidney size and parenchymal thickness in AKI or CKD. Increased renal echogenicity is associated with acute and chronic medical renal disease, but this is nonspecific and does not correlate well with renal function. Patients with AKI have only a 30% to 40% chance of increased echogenicity [4,28]. Alternatively, small echogenic kidneys are diagnostic of CKD. Color Doppler is routinely used to assess global perfusion and confirm arterial and venous patency. Color Doppler will differentiate a dilated pelvis from prominent renal veins in the renal sinus and can confirm presence or absence of ureteral jets in the bladder. If there is contemporaneous imaging such as CT or MRI showing normal kidneys and no new risk factors for obstruction, additional US is not indicated. US Duplex Doppler Kidneys Retroperitoneal Renovascular causes of AKI are rare; renal artery stenosis was found in 1.5% of cases with AKI even when it was not the cause of AKI [4]. In an older series of intensive care patients, AKI was attributed to renal artery thrombosis, stenosis, or trauma in 1% [17]. The diagnosis of significant renal artery stenosis can be made by obtaining angle- corrected measurements of the peak systolic velocities in the aorta and main renal arteries. Using a cutoff value of 285 cm/s achieved sensitivity, specificity, and overall accuracy of 67%, 90%, and 81%, respectively, for >60% stenosis [32].

Renal Failure. Normal renal length is >10 cm in the third decade, but renal length correlates with height, sex, age (negative correlation), and weight in normal patients and varies with the state of hydration or presence of an obstruction [3]. Renal size/volume correlates with creatinine clearance [30]. Both kidney Renal Failure size and parenchymal thickness decrease in CKD [31]. Therefore, a normal kidney size suggests AKI rather than CKD. However, infiltrative and inflammatory diseases, as well as renal vein thrombosis, may increase kidney size and parenchymal thickness in AKI or CKD. Increased renal echogenicity is associated with acute and chronic medical renal disease, but this is nonspecific and does not correlate well with renal function. Patients with AKI have only a 30% to 40% chance of increased echogenicity [4,28]. Alternatively, small echogenic kidneys are diagnostic of CKD. Color Doppler is routinely used to assess global perfusion and confirm arterial and venous patency. Color Doppler will differentiate a dilated pelvis from prominent renal veins in the renal sinus and can confirm presence or absence of ureteral jets in the bladder. If there is contemporaneous imaging such as CT or MRI showing normal kidneys and no new risk factors for obstruction, additional US is not indicated. US Duplex Doppler Kidneys Retroperitoneal Renovascular causes of AKI are rare; renal artery stenosis was found in 1.5% of cases with AKI even when it was not the cause of AKI [4]. In an older series of intensive care patients, AKI was attributed to renal artery thrombosis, stenosis, or trauma in 1% [17]. The diagnosis of significant renal artery stenosis can be made by obtaining angle- corrected measurements of the peak systolic velocities in the aorta and main renal arteries. Using a cutoff value of 285 cm/s achieved sensitivity, specificity, and overall accuracy of 67%, 90%, and 81%, respectively, for >60% stenosis [32].

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Renal Failure

In a smaller series, using a cutoff value of 180 cm/s, the sensitivity and specificity of US were 85% and 84%, respectively, for >60% stenosis [18]. Renal artery duplex Doppler studies may be appropriate in selected patients with a high clinical suspicion of renal artery stenosis. Resistive index (RI) has been studied in patients with AKI as a means to detect intrarenal vasoconstriction and differentiate renal from prerenal AKI. An elevated RI has been reported to be an early predictor of early or persistent postoperative AKI after cardiac or hip surgery [33,34] or persistent AKI in critically ill patients [35] and is associated with intensive care unit mortality [36]. An elevated RI can predict progression to CKD [37]. However, an elevated intrarenal RI is not specific to the cause of AKI as RI depends on multiple physiologic and pathologic factors, including vascular compliance, age, atherosclerosis, renal damage, hypertension, heart rate, as well as intrinsic renal disease [33,37]. Serial RI measurement is largely a research tool at this time. Variant 2: Renal failure. Chronic kidney disease (CKD). Initial imaging. Arteriography Kidney Arteriography is reserved for intervention rather than for initial diagnosis. Treatment of renal artery stenosis may be considered, but a recent meta-analysis does not indicate a benefit in the preservation of renal function [38]. CT Abdomen and Pelvis Unenhanced CT is useful for further evaluation of US-detected hydronephrosis by determining level and cause of obstruction. CT is the most sensitive modality for urinary tract calculi [15]. Although CT can determine if there is hydronephrosis and assess renal size/volume, it is generally not considered the first-line imaging modality [16]. CT may be considered if US is not feasible or is nondiagnostic because of body habitus. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast for initial evaluation of CKD.

Renal Failure. In a smaller series, using a cutoff value of 180 cm/s, the sensitivity and specificity of US were 85% and 84%, respectively, for >60% stenosis [18]. Renal artery duplex Doppler studies may be appropriate in selected patients with a high clinical suspicion of renal artery stenosis. Resistive index (RI) has been studied in patients with AKI as a means to detect intrarenal vasoconstriction and differentiate renal from prerenal AKI. An elevated RI has been reported to be an early predictor of early or persistent postoperative AKI after cardiac or hip surgery [33,34] or persistent AKI in critically ill patients [35] and is associated with intensive care unit mortality [36]. An elevated RI can predict progression to CKD [37]. However, an elevated intrarenal RI is not specific to the cause of AKI as RI depends on multiple physiologic and pathologic factors, including vascular compliance, age, atherosclerosis, renal damage, hypertension, heart rate, as well as intrinsic renal disease [33,37]. Serial RI measurement is largely a research tool at this time. Variant 2: Renal failure. Chronic kidney disease (CKD). Initial imaging. Arteriography Kidney Arteriography is reserved for intervention rather than for initial diagnosis. Treatment of renal artery stenosis may be considered, but a recent meta-analysis does not indicate a benefit in the preservation of renal function [38]. CT Abdomen and Pelvis Unenhanced CT is useful for further evaluation of US-detected hydronephrosis by determining level and cause of obstruction. CT is the most sensitive modality for urinary tract calculi [15]. Although CT can determine if there is hydronephrosis and assess renal size/volume, it is generally not considered the first-line imaging modality [16]. CT may be considered if US is not feasible or is nondiagnostic because of body habitus. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast for initial evaluation of CKD.

69492

acrac_69492_10

Renal Failure

Although CT with IV contrast may be feasible depending on the stage of CKD, it is not appropriate for the diagnosis of and determination of the cause of CKD. There is no relevant literature regarding the use of CT abdomen and pelvis with IV contrast for initial evaluation of CKD. CT Abdomen There is no relevant literature regarding the use of CT abdomen in the initial evaluation of CKD. CTA Abdomen and Pelvis In CKD, contrast-enhanced CTA might be carefully considered for vascular thrombosis or stenosis depending on the GFR and risk-benefit ratio. In one study of 1,007 patients with CKD undergoing US, renal artery stenosis was found in 4.3% of patients [39]. There is no relevant literature regarding the use of CTA abdomen and pelvis for initial evaluation of CKD. Renal Failure CT Urography There is no relevant literature regarding the use of CTU in the initial evaluation of CKD. MRA Abdomen MRA is indicated when there is a high suspicion of a renovascular cause of CKD, which is rare. In one study of 1,007 patients with CKD undergoing US, renal artery stenosis was found in 4.3% of patients [39]. Unenhanced MRA techniques may be an option. When compared with contrast-enhanced CTA in the detection of <50% or >50% renal artery stenosis, an unenhanced MRA was reported to have a sensitivity, specificity, and accuracy of 74%, 93%, and 90%, respectively [19]. For contrast-enhanced MRA, a group II contrast agent using lowest dose that obtains a diagnostic study should be used [9]. In the detection o f >60% renal artery stenosis, c ontrast-enhanced MRA has a sensitivity of 93% and specificity of 93% compared to 85% and 84%, respectively, for Doppler US [18]. MRI Abdomen and Pelvis There is no relevant literature regarding the use of MRI abdomen and pelvis without and with IV contrast in the initial evaluation of CKD. MRI Abdomen Unenhanced MRI may be used for characterization of level and cause of obstruction or evaluation of renal morphologic abnormalities.

Renal Failure. Although CT with IV contrast may be feasible depending on the stage of CKD, it is not appropriate for the diagnosis of and determination of the cause of CKD. There is no relevant literature regarding the use of CT abdomen and pelvis with IV contrast for initial evaluation of CKD. CT Abdomen There is no relevant literature regarding the use of CT abdomen in the initial evaluation of CKD. CTA Abdomen and Pelvis In CKD, contrast-enhanced CTA might be carefully considered for vascular thrombosis or stenosis depending on the GFR and risk-benefit ratio. In one study of 1,007 patients with CKD undergoing US, renal artery stenosis was found in 4.3% of patients [39]. There is no relevant literature regarding the use of CTA abdomen and pelvis for initial evaluation of CKD. Renal Failure CT Urography There is no relevant literature regarding the use of CTU in the initial evaluation of CKD. MRA Abdomen MRA is indicated when there is a high suspicion of a renovascular cause of CKD, which is rare. In one study of 1,007 patients with CKD undergoing US, renal artery stenosis was found in 4.3% of patients [39]. Unenhanced MRA techniques may be an option. When compared with contrast-enhanced CTA in the detection of <50% or >50% renal artery stenosis, an unenhanced MRA was reported to have a sensitivity, specificity, and accuracy of 74%, 93%, and 90%, respectively [19]. For contrast-enhanced MRA, a group II contrast agent using lowest dose that obtains a diagnostic study should be used [9]. In the detection o f >60% renal artery stenosis, c ontrast-enhanced MRA has a sensitivity of 93% and specificity of 93% compared to 85% and 84%, respectively, for Doppler US [18]. MRI Abdomen and Pelvis There is no relevant literature regarding the use of MRI abdomen and pelvis without and with IV contrast in the initial evaluation of CKD. MRI Abdomen Unenhanced MRI may be used for characterization of level and cause of obstruction or evaluation of renal morphologic abnormalities.

69492

acrac_69492_11

Renal Failure

Functional MRI techniques such as BOLD, ASL, DWI, and DKI that provide information on renal perfusion, oxygenation, and diffusion are still the subject of active research [21,22]. The use of contrast should be considered only after evaluation of the risk-benefit ratio and degree of renal function [9]. There is no literature to support any added diagnostic value of the use of IV contrast and its attendant risks, and it is not appropriate for the diagnosis of and determination of the cause of CKD. There is no relevant literature regarding the use of MRI abdomen without and with IV contrast in the initial evaluation of CKD. MR Urography There is no relevant literature regarding the use of MRU in the initial evaluation of CKD. Radiography Abdomen and Pelvis The role of abdominal radiography in CKD is limited to evaluation of renal stone disease, which acknowledges that radiography is less sensitive than CT for stone disease [24]. Signs of renal osteodystrophy confirm the presence of CKD. DMSA Renal Scan Tc-99m DMSA scintigraphy is ideal for functional renal cortical imaging and is most useful for detection of focal renal parenchymal abnormalities and scars in the setting of acute or chronic pyelonephritis or for differential renal function. Serial imaging may be useful for monitoring renal cortical scarring. The literature search did not identify any studies regarding the use of Tc-99m DMSA as a first-line test in the evaluation of CKD. MAG3 Renal Scan The literature search did not identify any studies regarding the use of Tc-99m MAG3 as a first-line test in the evaluation of CKD. US Kidneys Retroperitoneum US can differentiate AKI from CKD by determining renal size and volume. Renal length correlates with renal function in CKD [30,40-42]. Renal volume may be less useful given the contribution of renal sinus fat. In CKD, the kidneys are typically small with loss of global parenchymal and cortical thickness [42,43]. Renal length <9 cm in an adult is definitely abnormal [44].

Renal Failure. Functional MRI techniques such as BOLD, ASL, DWI, and DKI that provide information on renal perfusion, oxygenation, and diffusion are still the subject of active research [21,22]. The use of contrast should be considered only after evaluation of the risk-benefit ratio and degree of renal function [9]. There is no literature to support any added diagnostic value of the use of IV contrast and its attendant risks, and it is not appropriate for the diagnosis of and determination of the cause of CKD. There is no relevant literature regarding the use of MRI abdomen without and with IV contrast in the initial evaluation of CKD. MR Urography There is no relevant literature regarding the use of MRU in the initial evaluation of CKD. Radiography Abdomen and Pelvis The role of abdominal radiography in CKD is limited to evaluation of renal stone disease, which acknowledges that radiography is less sensitive than CT for stone disease [24]. Signs of renal osteodystrophy confirm the presence of CKD. DMSA Renal Scan Tc-99m DMSA scintigraphy is ideal for functional renal cortical imaging and is most useful for detection of focal renal parenchymal abnormalities and scars in the setting of acute or chronic pyelonephritis or for differential renal function. Serial imaging may be useful for monitoring renal cortical scarring. The literature search did not identify any studies regarding the use of Tc-99m DMSA as a first-line test in the evaluation of CKD. MAG3 Renal Scan The literature search did not identify any studies regarding the use of Tc-99m MAG3 as a first-line test in the evaluation of CKD. US Kidneys Retroperitoneum US can differentiate AKI from CKD by determining renal size and volume. Renal length correlates with renal function in CKD [30,40-42]. Renal volume may be less useful given the contribution of renal sinus fat. In CKD, the kidneys are typically small with loss of global parenchymal and cortical thickness [42,43]. Renal length <9 cm in an adult is definitely abnormal [44].

69492

acrac_69492_12

Renal Failure

It should be emphasized that normal-sized kidneys do not exclude CKD as renal size is initially preserved in diabetic nephropathy or infiltrative disorders. Increase in renal echogenicity is a nonspecific subjective manifestation of renal disease. In a series of 1,007 patients with CKD, abnormalities were detected in 26.8% of patients at initial US evaluation [39]. The most common US findings were increased echogenicity in 10.3%, cortical t hinning in 4 . 3%, renal artery stenosis in 4. 3%, and hydronephrosis in 1.9% of patients [39]. However, these findings contributed to the diagnosis in only 5 . 9% o f patients and affected management in 3.3% of patients [39]. Renal Failure The low impact on management does not support the use of US for routine surveillance of CKD. US may be indicated when there is a prior history of stones or obstruction, renal artery stenosis, frequent urinary tract infections, or family history of autosomal dominant polycystic kidney disease [39]. In patients with CKD and diabetes or hypertension, US has minimal impact on diagnosis and management [6,8]. US Duplex Doppler Kidneys Retroperitoneal A high RI can be a predictor of progression of CKD, but an elevated RI is not specific to renal disease [37], and threshold values vary in the literature. The literature search did not identify any studies regarding the use of RIs US in the initial evaluation of CKD. For renovascular disease, US is a low-yield test unless the patient has a history of renal artery stenosis [39]. Variant 3: Renal failure. Kidney disease of unknown duration. Initial imaging. Some patients will present without prior laboratory results and cannot be definitively categorized into AKI or CKD. In these patients, a detailed history, physical examination, and laboratory analysis of blood (for serum creatinine, blood urea nitrogen, complete blood count, and differential) and urine (microscopy for casts and epithelial cells, chemistry, and biomarkers) will be obtained in addition to imaging.

Renal Failure. It should be emphasized that normal-sized kidneys do not exclude CKD as renal size is initially preserved in diabetic nephropathy or infiltrative disorders. Increase in renal echogenicity is a nonspecific subjective manifestation of renal disease. In a series of 1,007 patients with CKD, abnormalities were detected in 26.8% of patients at initial US evaluation [39]. The most common US findings were increased echogenicity in 10.3%, cortical t hinning in 4 . 3%, renal artery stenosis in 4. 3%, and hydronephrosis in 1.9% of patients [39]. However, these findings contributed to the diagnosis in only 5 . 9% o f patients and affected management in 3.3% of patients [39]. Renal Failure The low impact on management does not support the use of US for routine surveillance of CKD. US may be indicated when there is a prior history of stones or obstruction, renal artery stenosis, frequent urinary tract infections, or family history of autosomal dominant polycystic kidney disease [39]. In patients with CKD and diabetes or hypertension, US has minimal impact on diagnosis and management [6,8]. US Duplex Doppler Kidneys Retroperitoneal A high RI can be a predictor of progression of CKD, but an elevated RI is not specific to renal disease [37], and threshold values vary in the literature. The literature search did not identify any studies regarding the use of RIs US in the initial evaluation of CKD. For renovascular disease, US is a low-yield test unless the patient has a history of renal artery stenosis [39]. Variant 3: Renal failure. Kidney disease of unknown duration. Initial imaging. Some patients will present without prior laboratory results and cannot be definitively categorized into AKI or CKD. In these patients, a detailed history, physical examination, and laboratory analysis of blood (for serum creatinine, blood urea nitrogen, complete blood count, and differential) and urine (microscopy for casts and epithelial cells, chemistry, and biomarkers) will be obtained in addition to imaging.

69492

acrac_69492_13

Renal Failure

More frequent measurement of serum creatinine will detect the more rapid deterioration of AKI. The imaging workup is similar to patients with AKI. Arteriography Kidney Arteriography is reserved for intervention rather than for the initial diagnosis of renal failure. Renal revascularization may be considered in a very select group of patients with AKI. There is no relevant literature regarding the use of arteriography in the evaluation of renal failure of unknown duration. CT Abdomen and Pelvis Unenhanced CT of the abdomen and pelvis is useful for characterization of US-detected hydronephrosis by determining level and cause of obstruction. CT is the most sensitive modality for urinary tract calculi and more sensitive than US for retroperitoneal pathology [15]. Although CT can determine whether there is hydronephrosis and measure renal size/volume, it is generally not considered a first-line imaging modality [16]. CT may be considered if US is not feasible or is nondiagnostic because body habitus. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast in the evaluation of renal failure of unknown duration. Iodinated contrast may be administered to patients established on dialysis without residual renal function. However, CT with IV contrast is not appropriate for the diagnosis of and determination of the cause of kidney failure. CT Abdomen There is no relevant literature regarding the use of CT abdomen in the initial evaluation of renal failure of unknown duration. CTA Abdomen and Pelvis Contrast-enhanced CTA abdomen and pelvis is very rarely indicated in these patients, given the potential nephrotoxicity. The risk-benefit ratio should be carefully evaluated if CTA is necessary to diagnose vascular thrombosis or stenosis. The lowest dose of contrast needed for a diagnostic study should be used and supplemented with adequate volume expansion [9].

Renal Failure. More frequent measurement of serum creatinine will detect the more rapid deterioration of AKI. The imaging workup is similar to patients with AKI. Arteriography Kidney Arteriography is reserved for intervention rather than for the initial diagnosis of renal failure. Renal revascularization may be considered in a very select group of patients with AKI. There is no relevant literature regarding the use of arteriography in the evaluation of renal failure of unknown duration. CT Abdomen and Pelvis Unenhanced CT of the abdomen and pelvis is useful for characterization of US-detected hydronephrosis by determining level and cause of obstruction. CT is the most sensitive modality for urinary tract calculi and more sensitive than US for retroperitoneal pathology [15]. Although CT can determine whether there is hydronephrosis and measure renal size/volume, it is generally not considered a first-line imaging modality [16]. CT may be considered if US is not feasible or is nondiagnostic because body habitus. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast in the evaluation of renal failure of unknown duration. Iodinated contrast may be administered to patients established on dialysis without residual renal function. However, CT with IV contrast is not appropriate for the diagnosis of and determination of the cause of kidney failure. CT Abdomen There is no relevant literature regarding the use of CT abdomen in the initial evaluation of renal failure of unknown duration. CTA Abdomen and Pelvis Contrast-enhanced CTA abdomen and pelvis is very rarely indicated in these patients, given the potential nephrotoxicity. The risk-benefit ratio should be carefully evaluated if CTA is necessary to diagnose vascular thrombosis or stenosis. The lowest dose of contrast needed for a diagnostic study should be used and supplemented with adequate volume expansion [9].

69492

acrac_69492_14

Renal Failure

There is no relevant literature regarding the use of CTA abdomen and pelvis in the evaluation of renal failure of unknown duration. CT Urography There is no relevant literature regarding the use of CTU in the evaluation of renal failure of unknown duration and the requirement for IV contrast limits its applicability. MRA Abdomen and Pelvis There is no relevant literature regarding the use of MRA abdomen and pelvis without and with IV contrast in the evaluation of renal failure of unknown duration. MRA may be indicated when there is a high suspicion of a renovascular cause of AKI/CKD, such as renal artery stenosis, thrombosis, or arterial injury after trauma, all of which are rare [4,17]. Unenhanced MRA techniques, such as time-spatial labeling inversion pulse or steady-state free precession, have a sensitivity of 73% to 100%, specificity of 82% to 99%, and negative predictive value of 88% to 100% in the diagnosis of >50% renal artery stenosis [19,20]. Renal Failure There is no relevant literature regarding the use of MRA abdomen without IV contrast in the evaluation of renal failure of unknown duration. For contrast-enhanced MRA, a group II contrast agent should be used [9]. For the detection of >60% renal artery stenosis, an contrast-enhanced MRA has a sensitivity of 93% and a specificity of 93% compared with 85% and 84%, respectively, for Doppler US [18]. MRI Abdomen and Pelvis Unenhanced MRI of the abdomen and pelvis may be used to evaluate extent and cause of suspected urinary tract obstruction. However, there is no relevant literature regarding the use of MRI abdomen and pelvis in the initial evaluation of renal failure of unknown duration. MRI Abdomen There is no relevant literature regarding the use of MRI abdomen without and with IV contrast in the initial evaluation of renal failure of unknown duration. MRI performed without IV contrast can be used for further characterization of the cause and level of obstruction and for evaluation of some renal morphologic abnormalities.

Renal Failure. There is no relevant literature regarding the use of CTA abdomen and pelvis in the evaluation of renal failure of unknown duration. CT Urography There is no relevant literature regarding the use of CTU in the evaluation of renal failure of unknown duration and the requirement for IV contrast limits its applicability. MRA Abdomen and Pelvis There is no relevant literature regarding the use of MRA abdomen and pelvis without and with IV contrast in the evaluation of renal failure of unknown duration. MRA may be indicated when there is a high suspicion of a renovascular cause of AKI/CKD, such as renal artery stenosis, thrombosis, or arterial injury after trauma, all of which are rare [4,17]. Unenhanced MRA techniques, such as time-spatial labeling inversion pulse or steady-state free precession, have a sensitivity of 73% to 100%, specificity of 82% to 99%, and negative predictive value of 88% to 100% in the diagnosis of >50% renal artery stenosis [19,20]. Renal Failure There is no relevant literature regarding the use of MRA abdomen without IV contrast in the evaluation of renal failure of unknown duration. For contrast-enhanced MRA, a group II contrast agent should be used [9]. For the detection of >60% renal artery stenosis, an contrast-enhanced MRA has a sensitivity of 93% and a specificity of 93% compared with 85% and 84%, respectively, for Doppler US [18]. MRI Abdomen and Pelvis Unenhanced MRI of the abdomen and pelvis may be used to evaluate extent and cause of suspected urinary tract obstruction. However, there is no relevant literature regarding the use of MRI abdomen and pelvis in the initial evaluation of renal failure of unknown duration. MRI Abdomen There is no relevant literature regarding the use of MRI abdomen without and with IV contrast in the initial evaluation of renal failure of unknown duration. MRI performed without IV contrast can be used for further characterization of the cause and level of obstruction and for evaluation of some renal morphologic abnormalities.

69492

acrac_69492_15

Renal Failure

Alterations in corticomedullary differentiation are recognized but are nonspecific. Acute cortical necrosis can be specifically diagnosed when there is a low T2 signal rim at the corticomedullary junction and absence of cortical enhancement following contrast administration [23]. Functional MRI techniques , such as BOLD, AS L, DWI , and DKI that p rovide information on renal p erfusion, oxygenation, and diffusion are still the subject of active research [21,22]. MR Urography There is no relevant literature regarding the use of MRU in the initial evaluation of renal failure of unknown duration. However, nonenhanced contrast MRU may provide additional information in patients with renal failure secondary to obstruction. Radiography Abdomen and Pelvis There is no role for radiography in AKI/CKD other than for evaluation of renal stone disease, which acknowledges that radiography is less sensitive than CT for stone disease [24]. DMSA Renal Scan Tc-99m DMSA scintigraphy is ideal for functional renal cortical imaging and is most useful for detection of focal renal parenchymal abnormalities and scars in the setting of acute or chronic pyelonephritis or for differential renal function. The literature search did not identify any studies regarding the use of Tc-99m DMSA as a first-line test in the evaluation of renal failure of unknown duration. MAG3 Renal Scan The literature search did not identify any studies regarding the use of Tc-99m MAG3 as a first-line test in the evaluation of renal failure of unknown duration. US Kidneys Retroperitoneum US has greatest diagnostic value in the detection of hydronephrosis associated with urinary tract obstruction [4] with a sensitivity >90% for hydronephrosis and bladder distension [26]. However, even in hospitalized patients with AKI, the prevalence of hydronephrosis is low, ranging from 5% to 10%, with obstruction the cause of AKI in <45.2% of patients with hydronephrosis [4,27-29].

Renal Failure. Alterations in corticomedullary differentiation are recognized but are nonspecific. Acute cortical necrosis can be specifically diagnosed when there is a low T2 signal rim at the corticomedullary junction and absence of cortical enhancement following contrast administration [23]. Functional MRI techniques , such as BOLD, AS L, DWI , and DKI that p rovide information on renal p erfusion, oxygenation, and diffusion are still the subject of active research [21,22]. MR Urography There is no relevant literature regarding the use of MRU in the initial evaluation of renal failure of unknown duration. However, nonenhanced contrast MRU may provide additional information in patients with renal failure secondary to obstruction. Radiography Abdomen and Pelvis There is no role for radiography in AKI/CKD other than for evaluation of renal stone disease, which acknowledges that radiography is less sensitive than CT for stone disease [24]. DMSA Renal Scan Tc-99m DMSA scintigraphy is ideal for functional renal cortical imaging and is most useful for detection of focal renal parenchymal abnormalities and scars in the setting of acute or chronic pyelonephritis or for differential renal function. The literature search did not identify any studies regarding the use of Tc-99m DMSA as a first-line test in the evaluation of renal failure of unknown duration. MAG3 Renal Scan The literature search did not identify any studies regarding the use of Tc-99m MAG3 as a first-line test in the evaluation of renal failure of unknown duration. US Kidneys Retroperitoneum US has greatest diagnostic value in the detection of hydronephrosis associated with urinary tract obstruction [4] with a sensitivity >90% for hydronephrosis and bladder distension [26]. However, even in hospitalized patients with AKI, the prevalence of hydronephrosis is low, ranging from 5% to 10%, with obstruction the cause of AKI in <45.2% of patients with hydronephrosis [4,27-29].

69492

acrac_69492_16

Renal Failure

The highest yield for US is in patients with risk factors for urinary obstruction, such as pelvic tumors, bladder disorders, prostate hypertrophy, stone disease, and pelvic surgery. In patients without risk factors for obstruction, <1% of patients had US-detected obstruction [4]. Hydronephrosis does not necessarily indicate obstruction; a distended bladder, reflux, pregnancy, postobstructive dilation, or diuresis may cause ureteral and collecting system dilatation. A distended bladder should be decompressed, and the patient should be revaluated. False-negative US studies may be secondary to suboptimal quality, dehydration, early obstruction, or compression of the renal pelvis or ureters by tumors or fibrosis. A secondary role of US is the evaluation of renal size, echogenicity, and morphology to differentiate AKI from CKD and allow determination of prognosis. Normal renal length is >10 cm in the third decade, but renal length correlates with height, sex, age (negative correlation), and weight in normal patients and varies with the state of hydration or presence of an obstruction [3]. Renal size/volume correlates with creatinine clearance [30]. Both kidney size and parenchymal thickness decrease in CKD [31]. Therefore, a normal kidney size suggests AKI rather than CKD. However, infiltrative and inflammatory diseases, as well as renal vein thrombosis, may increase kidney size Renal Failure and parenchymal thickness in AKI or CKD. Increased renal echogenicity is associated with acute and chronic medical renal disease, but this is nonspecific and does not correlate well with renal function. Patients with AKI have only a 30% to 40% chance of increased echogenicity [4,28]. Alternatively, small echogenic kidneys are diagnostic of CKD. Color Doppler is routinely used to assess global perfusion and confirm arterial and venous patency. Color Doppler will differentiate a dilated pelvis from prominent renal veins in the renal sinus and can confirm presence or absence of ureteral jets in the bladder.

Renal Failure. The highest yield for US is in patients with risk factors for urinary obstruction, such as pelvic tumors, bladder disorders, prostate hypertrophy, stone disease, and pelvic surgery. In patients without risk factors for obstruction, <1% of patients had US-detected obstruction [4]. Hydronephrosis does not necessarily indicate obstruction; a distended bladder, reflux, pregnancy, postobstructive dilation, or diuresis may cause ureteral and collecting system dilatation. A distended bladder should be decompressed, and the patient should be revaluated. False-negative US studies may be secondary to suboptimal quality, dehydration, early obstruction, or compression of the renal pelvis or ureters by tumors or fibrosis. A secondary role of US is the evaluation of renal size, echogenicity, and morphology to differentiate AKI from CKD and allow determination of prognosis. Normal renal length is >10 cm in the third decade, but renal length correlates with height, sex, age (negative correlation), and weight in normal patients and varies with the state of hydration or presence of an obstruction [3]. Renal size/volume correlates with creatinine clearance [30]. Both kidney size and parenchymal thickness decrease in CKD [31]. Therefore, a normal kidney size suggests AKI rather than CKD. However, infiltrative and inflammatory diseases, as well as renal vein thrombosis, may increase kidney size Renal Failure and parenchymal thickness in AKI or CKD. Increased renal echogenicity is associated with acute and chronic medical renal disease, but this is nonspecific and does not correlate well with renal function. Patients with AKI have only a 30% to 40% chance of increased echogenicity [4,28]. Alternatively, small echogenic kidneys are diagnostic of CKD. Color Doppler is routinely used to assess global perfusion and confirm arterial and venous patency. Color Doppler will differentiate a dilated pelvis from prominent renal veins in the renal sinus and can confirm presence or absence of ureteral jets in the bladder.

69492

acrac_69492_17

Renal Failure

US Duplex Doppler Kidneys Retroperitoneal Renovascular causes of AKI/CKD are rare; renal artery stenosis was found in 1.5% of cases with AKI even when not the cause of AKI [4]. In an older series of intensive care patients, AKI was attributed to renal artery thrombosis, stenosis, or trauma in 1% [17]. The diagnosis of significant renal artery stenosis can be made by obtaining angle- corrected measurements of the peak systolic velocities in the aorta and main renal arteries. Using a cutoff value of 285 cm/s achieved sensitivity, specificity, and overall accuracy of 67%, 90%, and 81%, respectively, for >60% stenosis [32]. In a smaller series, using a cutoff value of 180 cm/s, the sensitivity and specificity of US were 85% and 84%, respectively, for >60% stenosis [18]. Renal artery duplex Doppler studies may be appropriate in selected patients with a high clinical suspicion of renal artery stenosis. RI has been studied in patients with AKI as a means to detect intrarenal vasoconstriction and differentiate renal from prerenal AKI. An elevated RI has been reported to be an early predictor of early or persistent postoperative AKI after cardiac or hip surgery [33,34], or persistent AKI in critically ill patients [35], and is associated with intensive care unit mortality [36]. An elevated RI can predict progression to CKD [37]. However, an elevated intrarenal RI is not specific to the cause of AKI, as RI depends on multiple physiologic and pathologic factors; including vascular compliance, age, atherosclerosis, renal damage, hypertension, heart rate, as well as intrinsic renal disease [33,37]. Serial RI measurement is largely a research tool at this time. Variant 4: Renal failure. Neurogenic bladder. Initial imaging.

Renal Failure. US Duplex Doppler Kidneys Retroperitoneal Renovascular causes of AKI/CKD are rare; renal artery stenosis was found in 1.5% of cases with AKI even when not the cause of AKI [4]. In an older series of intensive care patients, AKI was attributed to renal artery thrombosis, stenosis, or trauma in 1% [17]. The diagnosis of significant renal artery stenosis can be made by obtaining angle- corrected measurements of the peak systolic velocities in the aorta and main renal arteries. Using a cutoff value of 285 cm/s achieved sensitivity, specificity, and overall accuracy of 67%, 90%, and 81%, respectively, for >60% stenosis [32]. In a smaller series, using a cutoff value of 180 cm/s, the sensitivity and specificity of US were 85% and 84%, respectively, for >60% stenosis [18]. Renal artery duplex Doppler studies may be appropriate in selected patients with a high clinical suspicion of renal artery stenosis. RI has been studied in patients with AKI as a means to detect intrarenal vasoconstriction and differentiate renal from prerenal AKI. An elevated RI has been reported to be an early predictor of early or persistent postoperative AKI after cardiac or hip surgery [33,34], or persistent AKI in critically ill patients [35], and is associated with intensive care unit mortality [36]. An elevated RI can predict progression to CKD [37]. However, an elevated intrarenal RI is not specific to the cause of AKI, as RI depends on multiple physiologic and pathologic factors; including vascular compliance, age, atherosclerosis, renal damage, hypertension, heart rate, as well as intrinsic renal disease [33,37]. Serial RI measurement is largely a research tool at this time. Variant 4: Renal failure. Neurogenic bladder. Initial imaging.

69492

acrac_69492_18

Renal Failure

Patients with neurogenic bladder due to disorders affecting the central nervous system typically present with signs of urinary frequency, urgency, and bladder overactivity, but there is little recent peer-reviewed original research on the initial imaging of this condition associated with renal failure. Underactivity of the bladder is less common, and it is characterized by prolonged voiding with a sensation of incomplete emptying and hesitancy; however, imaging is not generally part of the evaluation of underactive bladder [45]. Approximately 26% of patients with neurogenic bladder from spina bifida will develop renal failure, but <2% progress to end-stage renal disease [46]. Nearly all patients with spinal cord injury have historically developed renal dysfunction, which has been a major cause of death until more recent advances in diagnosis and care [47]. Patients with spinal cord injury have a 7% risk of stone development within 10 years, and this can contribute to renal insufficiency [47]. Review of clinical history, physical examination, US and urodynamic studies are the key components of an initial diagnosis of neurogenic bladder in Europe [48], but recommendations vary by country. For example, urodynamic evaluation is not recommended in British guidelines [49]. CT Abdomen and Pelvis Unenhanced CT is useful for characterization of US-detected hydronephrosis by determining the level and cause of obstruction. CT can determine if there is hydronephrosis, measure renal size/volume, and assess urinary bladder distension and wall thickening but it is generally not considered a first-line imaging modality [16]. CT may be considered if US is not feasible or is nondiagnostic because of body habitus. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast in the evaluation of renal failure associated with neurogenic bladder, but CT with IV contrast is not a first-line test for evaluation of kidney failure due to neurogenic bladder.

Renal Failure. Patients with neurogenic bladder due to disorders affecting the central nervous system typically present with signs of urinary frequency, urgency, and bladder overactivity, but there is little recent peer-reviewed original research on the initial imaging of this condition associated with renal failure. Underactivity of the bladder is less common, and it is characterized by prolonged voiding with a sensation of incomplete emptying and hesitancy; however, imaging is not generally part of the evaluation of underactive bladder [45]. Approximately 26% of patients with neurogenic bladder from spina bifida will develop renal failure, but <2% progress to end-stage renal disease [46]. Nearly all patients with spinal cord injury have historically developed renal dysfunction, which has been a major cause of death until more recent advances in diagnosis and care [47]. Patients with spinal cord injury have a 7% risk of stone development within 10 years, and this can contribute to renal insufficiency [47]. Review of clinical history, physical examination, US and urodynamic studies are the key components of an initial diagnosis of neurogenic bladder in Europe [48], but recommendations vary by country. For example, urodynamic evaluation is not recommended in British guidelines [49]. CT Abdomen and Pelvis Unenhanced CT is useful for characterization of US-detected hydronephrosis by determining the level and cause of obstruction. CT can determine if there is hydronephrosis, measure renal size/volume, and assess urinary bladder distension and wall thickening but it is generally not considered a first-line imaging modality [16]. CT may be considered if US is not feasible or is nondiagnostic because of body habitus. There is no relevant literature regarding the use of CT abdomen and pelvis without and with IV contrast in the evaluation of renal failure associated with neurogenic bladder, but CT with IV contrast is not a first-line test for evaluation of kidney failure due to neurogenic bladder.

69492

acrac_69492_19

Renal Failure

Other options that do not use iodinated contrast are available. CT Abdomen Unenhanced CT is useful for characterization of US-detected hydronephrosis by determining the level and cause of obstruction if the pelvis is included. CT can determine if there is hydronephrosis and measure renal size/volume, but it is generally not considered a first-line imaging modality [16]. Renal Failure There is no relevant literature regarding the use of CT abdomen without and with IV contrast in the evaluation of renal failure associated with neurogenic bladder, but CT with IV contrast is not a first-line test for evaluation of kidney failure due to neurogenic bladder. Other options that do not use iodinated contrast are available. CTA Abdomen and Pelvis There is no role for CTA in the initial evaluation of renal failure associated with neurogenic bladder. CT Urography There is no relevant literature for CTU in the initial evaluation of renal failure associated with neurogenic bladder. Fluoroscopy Cystography There is no role for cystography in the evaluation of neurogenic bladder other than as a method of visualization during video urodynamics. Fluoroscopy Voiding Cystourethrography Voiding cystourethrography is used to image the bladder wall and urethra and evaluate for vesicoureteral reflux but is not part of the evaluation of renal failure. There is no relevant literature regarding the use of voiding cystourethrography in the initial renal failure in a patient with neurogenic bladder. MRI Abdomen and Pelvis MRI can show the urinary system well, and T2-weighted imaging can demonstrate hydronephrosis and hydroureter as well as US. Likewise, the urinary bladder can be well-visualized. In one review from Asia, MRI was favored above US for better evaluation of the collecting systems and ureters, which were shown in the coronal plane [50].

Renal Failure. Other options that do not use iodinated contrast are available. CT Abdomen Unenhanced CT is useful for characterization of US-detected hydronephrosis by determining the level and cause of obstruction if the pelvis is included. CT can determine if there is hydronephrosis and measure renal size/volume, but it is generally not considered a first-line imaging modality [16]. Renal Failure There is no relevant literature regarding the use of CT abdomen without and with IV contrast in the evaluation of renal failure associated with neurogenic bladder, but CT with IV contrast is not a first-line test for evaluation of kidney failure due to neurogenic bladder. Other options that do not use iodinated contrast are available. CTA Abdomen and Pelvis There is no role for CTA in the initial evaluation of renal failure associated with neurogenic bladder. CT Urography There is no relevant literature for CTU in the initial evaluation of renal failure associated with neurogenic bladder. Fluoroscopy Cystography There is no role for cystography in the evaluation of neurogenic bladder other than as a method of visualization during video urodynamics. Fluoroscopy Voiding Cystourethrography Voiding cystourethrography is used to image the bladder wall and urethra and evaluate for vesicoureteral reflux but is not part of the evaluation of renal failure. There is no relevant literature regarding the use of voiding cystourethrography in the initial renal failure in a patient with neurogenic bladder. MRI Abdomen and Pelvis MRI can show the urinary system well, and T2-weighted imaging can demonstrate hydronephrosis and hydroureter as well as US. Likewise, the urinary bladder can be well-visualized. In one review from Asia, MRI was favored above US for better evaluation of the collecting systems and ureters, which were shown in the coronal plane [50].

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Renal Failure

However, MRI of the abdomen and pelvis is not routinely used in the evaluation of renal failure associated with neurogenic bladder regardless of whether or not IV contrast is administered. MRI Abdomen There is no relevant literature for MRI abdomen in the initial evaluation of renal failure associated with neurogenic bladder, regardless of whether or not IV contrasted series are included. MR Urography There is no relevant literature for MRU in the initial evaluation of renal failure associated with neurogenic bladder. However, contrast-enhanced MRU is not routinely performed in this setting, and the majority of the information is obtained by unenhanced MRI sequences. Radiography Abdomen and Pelvis There is no role for radiography in initial evaluation of neurogenic bladder. However, it may be used in the long- term surveillance for development of renal stone disease, acknowledging that radiography is less sensitive than CT for detection of stone disease [24]. MAG3 Renal Scan There is no relevant literature regarding the use of Tc-99m MAG3 as a first-line test in the evaluation of renal failure associated with neurogenic bladder. US Kidneys Retroperitoneum The American Urological Association supports clinical evaluation and measurement of postvoid residual but does not specifically endorse US for this measurement. However, US is routinely used by urologists in the initial workup because it can easily measure bladder volume. In patients with neurogenic bladder and lower urinary tract symptoms, US and postvoid residual measurement is also supported by international guidelines [48,49,53]. In a study of 60 patients with neurogenic lower urinary tract dysfunction after spinal cord injury, a distended bladder anterior wall detrusor (hypoechoic layer) with a thickness <0.97 mm on US was 92% sensitive and 63% specific for risk assessment of renal damage [54].

Renal Failure. However, MRI of the abdomen and pelvis is not routinely used in the evaluation of renal failure associated with neurogenic bladder regardless of whether or not IV contrast is administered. MRI Abdomen There is no relevant literature for MRI abdomen in the initial evaluation of renal failure associated with neurogenic bladder, regardless of whether or not IV contrasted series are included. MR Urography There is no relevant literature for MRU in the initial evaluation of renal failure associated with neurogenic bladder. However, contrast-enhanced MRU is not routinely performed in this setting, and the majority of the information is obtained by unenhanced MRI sequences. Radiography Abdomen and Pelvis There is no role for radiography in initial evaluation of neurogenic bladder. However, it may be used in the long- term surveillance for development of renal stone disease, acknowledging that radiography is less sensitive than CT for detection of stone disease [24]. MAG3 Renal Scan There is no relevant literature regarding the use of Tc-99m MAG3 as a first-line test in the evaluation of renal failure associated with neurogenic bladder. US Kidneys Retroperitoneum The American Urological Association supports clinical evaluation and measurement of postvoid residual but does not specifically endorse US for this measurement. However, US is routinely used by urologists in the initial workup because it can easily measure bladder volume. In patients with neurogenic bladder and lower urinary tract symptoms, US and postvoid residual measurement is also supported by international guidelines [48,49,53]. In a study of 60 patients with neurogenic lower urinary tract dysfunction after spinal cord injury, a distended bladder anterior wall detrusor (hypoechoic layer) with a thickness <0.97 mm on US was 92% sensitive and 63% specific for risk assessment of renal damage [54].

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

Aortic dissections are the results of a disruption in the aortic wall with blood flow into the media resulting in a true and false lumen, which may propagate antegrade or retrograde. Aortic dissections are classified by acuity, anatomic location of entry tear, extent of false lumen, and presence or absence of complicating features. The Stanford classification is commonly used to categorize aortic dissections. Type A dissection involves the ascending aorta (and may extend distally), and type B dissection is limited to the aortic arch and descending thoracic aorta. Complicating features include cerebral, coronary, and/or visceral malperfusion syndrome as well as rupture. Aortic dissections may require emergent surgical repair, thoracic endovascular aortic repair (EVAR), or other endovascular interventions to treat malperfusion syndromes following initial medical therapies. Aneurysmal expansion of the false lumen occurs in up to 50% of patients requiring follow-up imaging. Traditionally, treatment for thoracoabdominal aneurysm or dissection has been surgical. Although surgical repair demonstrated a survival benefit over medical management, open TAAA repair carries high mortality and morbidity risks [3-5]. A 2016 analysis of outcomes of more than 3,000 TAAA repairs reports an operative mortality rate of 7.5%, with permanent paraplegia in 2.9%, permanent renal failure in 5.7%, and stroke in 2.2% for a total composite rate of an adverse event of 14.4% [3]. Over the past 10 to 20 years, alternative treatment regimens have been 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]

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. Aortic dissections are the results of a disruption in the aortic wall with blood flow into the media resulting in a true and false lumen, which may propagate antegrade or retrograde. Aortic dissections are classified by acuity, anatomic location of entry tear, extent of false lumen, and presence or absence of complicating features. The Stanford classification is commonly used to categorize aortic dissections. Type A dissection involves the ascending aorta (and may extend distally), and type B dissection is limited to the aortic arch and descending thoracic aorta. Complicating features include cerebral, coronary, and/or visceral malperfusion syndrome as well as rupture. Aortic dissections may require emergent surgical repair, thoracic endovascular aortic repair (EVAR), or other endovascular interventions to treat malperfusion syndromes following initial medical therapies. Aneurysmal expansion of the false lumen occurs in up to 50% of patients requiring follow-up imaging. Traditionally, treatment for thoracoabdominal aneurysm or dissection has been surgical. Although surgical repair demonstrated a survival benefit over medical management, open TAAA repair carries high mortality and morbidity risks [3-5]. A 2016 analysis of outcomes of more than 3,000 TAAA repairs reports an operative mortality rate of 7.5%, with permanent paraplegia in 2.9%, permanent renal failure in 5.7%, and stroke in 2.2% for a total composite rate of an adverse event of 14.4% [3]. Over the past 10 to 20 years, alternative treatment regimens have been 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]

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

Thoracoabdominal Aortic Aneurysm or Dissection developed for some patient groups including hybrid repair and entirely endovascular repair. In hybrid repair, a combination of surgical and endovascular techniques is used, often in a staged format, with techniques including abdominal debranching followed by thoracic endovascular repair. Hybrid repairs showed favorable results in several series, although with aortic related mortality rates of 9%, 14%, and 14% at 1, 2, and 5 years, respectively, in one study [6-8]. More recently, a number of endovascular techniques have been used for repair, including thoracic EVAR, EVAR with parallel (eg, chimney/snorkel) stents into the branch artery, fenestrated EVAR, and branched EVAR [9-12]. Multiple studies have found encouraging results in terms of technical success, intraprocedural mortality, and branch vessel patency, although with high rates of reintervention for endoleaks [10,13-16]. Similarly, techniques for endovascular treatment of type B dissection have also been refined over the past decades, with new innovations in treating type A dissection emerging as well. The decision of surgical versus hybrid or endovascular repair is based on the characteristics of the aneurysm or dissection, along with factors such as suitability for surgery and patient preference. Regardless of type of treatment, postprocedural surveillance is important because patients with poor compliance with follow-up imaging are found to have higher rates of aortic rupture [17]. Special Imaging Considerations As MRI technology and sequences have continued to improve, multiple new sequences and protocols have been developed for assessment of the aorta. In particular, sequences aimed at evaluating flow dynamics and aortic wall stress have been used to predict aneurysm growth [19-24].

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. Thoracoabdominal Aortic Aneurysm or Dissection developed for some patient groups including hybrid repair and entirely endovascular repair. In hybrid repair, a combination of surgical and endovascular techniques is used, often in a staged format, with techniques including abdominal debranching followed by thoracic endovascular repair. Hybrid repairs showed favorable results in several series, although with aortic related mortality rates of 9%, 14%, and 14% at 1, 2, and 5 years, respectively, in one study [6-8]. More recently, a number of endovascular techniques have been used for repair, including thoracic EVAR, EVAR with parallel (eg, chimney/snorkel) stents into the branch artery, fenestrated EVAR, and branched EVAR [9-12]. Multiple studies have found encouraging results in terms of technical success, intraprocedural mortality, and branch vessel patency, although with high rates of reintervention for endoleaks [10,13-16]. Similarly, techniques for endovascular treatment of type B dissection have also been refined over the past decades, with new innovations in treating type A dissection emerging as well. The decision of surgical versus hybrid or endovascular repair is based on the characteristics of the aneurysm or dissection, along with factors such as suitability for surgery and patient preference. Regardless of type of treatment, postprocedural surveillance is important because patients with poor compliance with follow-up imaging are found to have higher rates of aortic rupture [17]. Special Imaging Considerations As MRI technology and sequences have continued to improve, multiple new sequences and protocols have been developed for assessment of the aorta. In particular, sequences aimed at evaluating flow dynamics and aortic wall stress have been used to predict aneurysm growth [19-24].

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

Other authors have advocated for the use of superparamagnetic iron oxide given intravenously to assess for inflammatory changes in the aortic wall [25,26]. Continued innovation has allowed advancement in sequences and techniques such as 4-D MRI for evaluation of TAAA or dissection, most commonly used at academic institutions. Discussion of Procedures by Variant Variant 1: Follow-up of known thoracoabdominal aortic aneurysm or dissection without repair. Without or with new symptoms. Aortography Chest Abdomen Pelvis Aortogram with digital subtraction angiography (DSA) for evaluation of the thoracic and abdominal aorta has a sensitivity of up to 90% and a specificity of 95% for acute aortic pathology [27]. Although it has the advantage of allowing immediate intervention if an abnormality is identified, aortography is an invasive procedure that is now typically performed for treatment after diagnosis of a new or worsening aortic pathology. Additionally, a 2003 study comparing MR angiography (MRA) with angiography suggested increased accuracy of MRA in assessing vessel diameter: a key component of follow-up for TAAA or dissection [28]. CT Chest, Abdomen, and Pelvis With IV Contrast There is no relevant literature regarding venous phase CT chest, abdomen, and pelvis for the follow-up of known thoracoabdominal aneurysm or dissection, because most follow-up imaging for known dissection or aneurysm uses an arterially timed contrast bolus in the form of a CT angiography (CTA) (discussed below). However, contrast- enhanced CT can provide information regarding the size and extent of aortic pathology as well as evaluate for extravascular pathology. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients.

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. Other authors have advocated for the use of superparamagnetic iron oxide given intravenously to assess for inflammatory changes in the aortic wall [25,26]. Continued innovation has allowed advancement in sequences and techniques such as 4-D MRI for evaluation of TAAA or dissection, most commonly used at academic institutions. Discussion of Procedures by Variant Variant 1: Follow-up of known thoracoabdominal aortic aneurysm or dissection without repair. Without or with new symptoms. Aortography Chest Abdomen Pelvis Aortogram with digital subtraction angiography (DSA) for evaluation of the thoracic and abdominal aorta has a sensitivity of up to 90% and a specificity of 95% for acute aortic pathology [27]. Although it has the advantage of allowing immediate intervention if an abnormality is identified, aortography is an invasive procedure that is now typically performed for treatment after diagnosis of a new or worsening aortic pathology. Additionally, a 2003 study comparing MR angiography (MRA) with angiography suggested increased accuracy of MRA in assessing vessel diameter: a key component of follow-up for TAAA or dissection [28]. CT Chest, Abdomen, and Pelvis With IV Contrast There is no relevant literature regarding venous phase CT chest, abdomen, and pelvis for the follow-up of known thoracoabdominal aneurysm or dissection, because most follow-up imaging for known dissection or aneurysm uses an arterially timed contrast bolus in the form of a CT angiography (CTA) (discussed below). However, contrast- enhanced CT can provide information regarding the size and extent of aortic pathology as well as evaluate for extravascular pathology. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients.

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

CT Chest, Abdomen, and Pelvis Without and With IV Contrast There is no relevant literature regarding venous phase CT chest, abdomen, and pelvis for the follow-up of known thoracoabdominal aneurysm or dissection because most follow-up imaging for known dissection or aneurysm uses an arterially timed contrast bolus in the form of a CTA (discussed below). However, contrast-enhanced CT can provide information regarding the size and extent of aortic pathology as well as evaluate for extravascular pathology. Although typically not performed for the purpose of follow-up of thoracoabdominal aortic pathology, multiphase CT performed to evaluate for extravascular pathology can often assess for acute changes in thoracoabdominal Thoracoabdominal Aortic Aneurysm or Dissection dissection or aneurysm, such as intramural hematoma. Unenhanced CT may be able to delineate extravascular complications such as hemorrhage or rupture. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CT Chest, Abdomen, and Pelvis Without IV Contrast There is no relevant literature for CT chest, abdomen, and pelvis without intravenous (IV) contrast for the follow- up of known thoracoabdominal aneurysm or dissection. Although most follow-up of known aortic disease is performed with IV contrast [29-31], select groups of patients may be monitored with unenhanced CT to evaluate measurements of aortic size, which may guide further management [32]. Unenhanced CT may be able to delineate extravascular complications such as hemorrhage or rupture [32]. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients.

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. CT Chest, Abdomen, and Pelvis Without and With IV Contrast There is no relevant literature regarding venous phase CT chest, abdomen, and pelvis for the follow-up of known thoracoabdominal aneurysm or dissection because most follow-up imaging for known dissection or aneurysm uses an arterially timed contrast bolus in the form of a CTA (discussed below). However, contrast-enhanced CT can provide information regarding the size and extent of aortic pathology as well as evaluate for extravascular pathology. Although typically not performed for the purpose of follow-up of thoracoabdominal aortic pathology, multiphase CT performed to evaluate for extravascular pathology can often assess for acute changes in thoracoabdominal Thoracoabdominal Aortic Aneurysm or Dissection dissection or aneurysm, such as intramural hematoma. Unenhanced CT may be able to delineate extravascular complications such as hemorrhage or rupture. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CT Chest, Abdomen, and Pelvis Without IV Contrast There is no relevant literature for CT chest, abdomen, and pelvis without intravenous (IV) contrast for the follow- up of known thoracoabdominal aneurysm or dissection. Although most follow-up of known aortic disease is performed with IV contrast [29-31], select groups of patients may be monitored with unenhanced CT to evaluate measurements of aortic size, which may guide further management [32]. Unenhanced CT may be able to delineate extravascular complications such as hemorrhage or rupture [32]. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients.

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

CT Chest and Abdomen With IV Contrast There is no relevant literature regarding venous phase CT chest and abdomen for the follow-up of known thoracoabdominal aneurysm or dissection because most follow-up imaging uses an arterially timed contrast bolus in the form of a CTA (discussed below). Compared with CT of the chest, abdomen, and pelvis, exclusion of the pelvis may result in incomplete evaluation of the extent of aortic pathology. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CT Chest and Abdomen Without and With IV Contrast There is no relevant literature regarding CT chest and abdomen without and with IV contrast for the follow-up of known thoracoabdominal aneurysm or dissection because most follow-up imaging uses an arterially timed contrast bolus in the form of a CTA (discussed below). Compared with CT of the chest, abdomen, and pelvis, exclusion of the pelvis may result in incomplete evaluation of the extent of aortic pathology. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CT Chest and Abdomen Without IV Contrast There is no relevant literature regarding CT chest and abdomen without IV contrast for the follow-up of known thoracoabdominal aneurysm or dissection because most follow-up imaging uses an arterially timed contrast bolus in the form of a CTA. Compared with CT of the chest, abdomen, and pelvis, exclusion of the pelvis may result in incomplete evaluation of the extent of aortic pathology. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CTA Chest, Abdomen, and Pelvis With IV Contrast CTA of the chest, abdomen, and pelvis with IV contrast uses fast acquisition times to allow for rapid evaluation of the aorta and diagnosis of pathology.

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. CT Chest and Abdomen With IV Contrast There is no relevant literature regarding venous phase CT chest and abdomen for the follow-up of known thoracoabdominal aneurysm or dissection because most follow-up imaging uses an arterially timed contrast bolus in the form of a CTA (discussed below). Compared with CT of the chest, abdomen, and pelvis, exclusion of the pelvis may result in incomplete evaluation of the extent of aortic pathology. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CT Chest and Abdomen Without and With IV Contrast There is no relevant literature regarding CT chest and abdomen without and with IV contrast for the follow-up of known thoracoabdominal aneurysm or dissection because most follow-up imaging uses an arterially timed contrast bolus in the form of a CTA (discussed below). Compared with CT of the chest, abdomen, and pelvis, exclusion of the pelvis may result in incomplete evaluation of the extent of aortic pathology. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CT Chest and Abdomen Without IV Contrast There is no relevant literature regarding CT chest and abdomen without IV contrast for the follow-up of known thoracoabdominal aneurysm or dissection because most follow-up imaging uses an arterially timed contrast bolus in the form of a CTA. Compared with CT of the chest, abdomen, and pelvis, exclusion of the pelvis may result in incomplete evaluation of the extent of aortic pathology. If venous phase or unenhanced CT has already been performed, additional imaging with CTA may not be required in some patients. CTA Chest, Abdomen, and Pelvis With IV Contrast CTA of the chest, abdomen, and pelvis with IV contrast uses fast acquisition times to allow for rapid evaluation of the aorta and diagnosis of pathology.

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

Fast acquisition times are particularly valuable in patients with known TAAA or dissection with new symptoms, given the high acuity of these conditions in the event of disease extension or worsening. The precise and reproducible measurements of the aorta with CTA are valuable for monitoring aortic growth and interval changes [33,34]. Electrocardiographically (ECG)-gated or triggered CTA is an additional option that can be used to evaluate the ascending aorta in patients with concern for conversion of a dissection into a type A dissection or for aneurysmal enlargement of the ascending aorta. With ECG gating, artifact from aortic pulsation is reduced and maximum interobserver variability of 1.2 mm in the ascending aorta has been reported, emphasizing the reproducibility of CTA [31,34]. Acquisition of thin axial slices with subsequent 3-D reconstruction along with homogenous luminal opacification allows for precise measurements and assessment of aortic anatomy, using postprocessing software for vessel analysis. Along with low interobserver variability, this allows for an excellent ability to detect changes in the aortic diameter or extent of dissection [31,33,34]. Furthermore, CTA can readily detect complications including thoracoabdominal aneurysm rupture or dissection extension causing malperfusion of the supra-aortic branch vessels, mesenteric arteries, renal arteries, lower extremities, or coronary arteries [31,35]. CTA has also been used in certain situations to predict enlargement of saccular aneurysms using flow dynamics [36]. Compared with CTA of the chest and abdomen, imaging of the pelvis carries the benefit of evaluation of the iliofemoral vessels to evaluate the extent of dissection or aneurysmal dilatation and suitability for possible endovascular intervention.

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. Fast acquisition times are particularly valuable in patients with known TAAA or dissection with new symptoms, given the high acuity of these conditions in the event of disease extension or worsening. The precise and reproducible measurements of the aorta with CTA are valuable for monitoring aortic growth and interval changes [33,34]. Electrocardiographically (ECG)-gated or triggered CTA is an additional option that can be used to evaluate the ascending aorta in patients with concern for conversion of a dissection into a type A dissection or for aneurysmal enlargement of the ascending aorta. With ECG gating, artifact from aortic pulsation is reduced and maximum interobserver variability of 1.2 mm in the ascending aorta has been reported, emphasizing the reproducibility of CTA [31,34]. Acquisition of thin axial slices with subsequent 3-D reconstruction along with homogenous luminal opacification allows for precise measurements and assessment of aortic anatomy, using postprocessing software for vessel analysis. Along with low interobserver variability, this allows for an excellent ability to detect changes in the aortic diameter or extent of dissection [31,33,34]. Furthermore, CTA can readily detect complications including thoracoabdominal aneurysm rupture or dissection extension causing malperfusion of the supra-aortic branch vessels, mesenteric arteries, renal arteries, lower extremities, or coronary arteries [31,35]. CTA has also been used in certain situations to predict enlargement of saccular aneurysms using flow dynamics [36]. Compared with CTA of the chest and abdomen, imaging of the pelvis carries the benefit of evaluation of the iliofemoral vessels to evaluate the extent of dissection or aneurysmal dilatation and suitability for possible endovascular intervention.

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

Thoracoabdominal Aortic Aneurysm or Dissection CTA Chest and Abdomen With IV Contrast Compared with CTA of the chest, abdomen, and pelvis, the lack of visualization of the iliofemoral vessels precludes evaluation for suitability for possible endovascular intervention or for aneurysm dilation/dissection of the iliac or femoral arteries if pathology extends to the bifurcation. MRA Chest, Abdomen, and Pelvis Without and With IV Contrast Similar to CTA, MRA of the thoracoabdominal aorta allows for precise and reproducible assessment or aortic sac size in aneurysm or extent of dissection in thoracoabdominal aortic dissection [33,37-39]. In patients with new symptoms, MRI has conventionally been used as a secondary imaging modality because of relatively long imaging times [40]. However, MRI can be used to accurately assess for acute aortic pathology in this clinical setting [40- 42]. Use of a contrast agent in MRA allows for 4-D evaluation of flow dynamics, with acquisition of multiple time- points allowing for detailed evaluation of flow dynamics associated with aortic aneurysm or dissection [43]. This can be used with a variety of unenhanced MRA techniques such as time-of-flight and phase-contrast imaging that can also allow for evaluation of aortic dissection and aneurysm [44,45]. Similar to CTA, ECG gating can be used for a more accurate assessment of the ascending thoracic aorta if concern exists for retrograde extension of pathology [46,47]. MRA can allow for the evaluation of aortic valve dysfunction associated with ascending aortic dilation or dissection, which cannot typically be identified on CTA [33,46,47]. MRI also allows evaluation for extravascular pathology. In a 2014 study, more than 80% of patients had at least one extravascular finding, with 6.4% found to have a major extravascular finding including neoplasm, spine infection, or pericardial effusion [48].

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. Thoracoabdominal Aortic Aneurysm or Dissection CTA Chest and Abdomen With IV Contrast Compared with CTA of the chest, abdomen, and pelvis, the lack of visualization of the iliofemoral vessels precludes evaluation for suitability for possible endovascular intervention or for aneurysm dilation/dissection of the iliac or femoral arteries if pathology extends to the bifurcation. MRA Chest, Abdomen, and Pelvis Without and With IV Contrast Similar to CTA, MRA of the thoracoabdominal aorta allows for precise and reproducible assessment or aortic sac size in aneurysm or extent of dissection in thoracoabdominal aortic dissection [33,37-39]. In patients with new symptoms, MRI has conventionally been used as a secondary imaging modality because of relatively long imaging times [40]. However, MRI can be used to accurately assess for acute aortic pathology in this clinical setting [40- 42]. Use of a contrast agent in MRA allows for 4-D evaluation of flow dynamics, with acquisition of multiple time- points allowing for detailed evaluation of flow dynamics associated with aortic aneurysm or dissection [43]. This can be used with a variety of unenhanced MRA techniques such as time-of-flight and phase-contrast imaging that can also allow for evaluation of aortic dissection and aneurysm [44,45]. Similar to CTA, ECG gating can be used for a more accurate assessment of the ascending thoracic aorta if concern exists for retrograde extension of pathology [46,47]. MRA can allow for the evaluation of aortic valve dysfunction associated with ascending aortic dilation or dissection, which cannot typically be identified on CTA [33,46,47]. MRI also allows evaluation for extravascular pathology. In a 2014 study, more than 80% of patients had at least one extravascular finding, with 6.4% found to have a major extravascular finding including neoplasm, spine infection, or pericardial effusion [48].

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

A 2018 comparative study with 45 patients divided into noncontrast-enhanced and blood pool contrast groups was performed to qualitatively and quantitatively evaluate image quality as well as reproducibility [47]. This study concluded that IV contrast allows for higher quality imaging with more reproducible and accurate vessel measurements [47]. The findings were consistent with a 2010 study supporting the use of IV contrast for vascular detail [49]. In contrast to these findings, however, multiple other studies have found similar accuracy and reproducibility in assessing vessel diameter between contrast- and noncontrast-enhanced MRI studies [44,50,51]. MRA Chest, Abdomen, and Pelvis Without IV Contrast Multiple unenhanced MRA techniques such as time-of-flight, phase-contrast imaging, and steady-state free precision (SSFP) have been developed that allow for the evaluation of aortic dissection and aneurysm [44,45]. Even without IV contrast, MRA can be used to precisely evaluate the thoracoabdominal aorta size, as well as for access vessel size, intraluminal thrombus, and branch vessel involvement [37,39]. A 2017 observational study comparing AAA measurements in CTA and noncontrast MRA showed strong agreement, with intraclass coefficient >0.99 and interobserver reproducibility >0.99 for both CTA and MRA [45]. This study also noted a potential benefit of noncontrast MRA allowing evaluation of the composition of intraluminal thrombus, potentially allowing for risk quantification for disease progression [45]. This finding was also supported by a follow-up 2019 article [52]. Although some studies have shown more accurate measurements with contrast-enhanced MRA compared with noncontrast MRA, other studies have shown an equal ability to detect aortic pathology and to measure aortic size [44,50,51].

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. A 2018 comparative study with 45 patients divided into noncontrast-enhanced and blood pool contrast groups was performed to qualitatively and quantitatively evaluate image quality as well as reproducibility [47]. This study concluded that IV contrast allows for higher quality imaging with more reproducible and accurate vessel measurements [47]. The findings were consistent with a 2010 study supporting the use of IV contrast for vascular detail [49]. In contrast to these findings, however, multiple other studies have found similar accuracy and reproducibility in assessing vessel diameter between contrast- and noncontrast-enhanced MRI studies [44,50,51]. MRA Chest, Abdomen, and Pelvis Without IV Contrast Multiple unenhanced MRA techniques such as time-of-flight, phase-contrast imaging, and steady-state free precision (SSFP) have been developed that allow for the evaluation of aortic dissection and aneurysm [44,45]. Even without IV contrast, MRA can be used to precisely evaluate the thoracoabdominal aorta size, as well as for access vessel size, intraluminal thrombus, and branch vessel involvement [37,39]. A 2017 observational study comparing AAA measurements in CTA and noncontrast MRA showed strong agreement, with intraclass coefficient >0.99 and interobserver reproducibility >0.99 for both CTA and MRA [45]. This study also noted a potential benefit of noncontrast MRA allowing evaluation of the composition of intraluminal thrombus, potentially allowing for risk quantification for disease progression [45]. This finding was also supported by a follow-up 2019 article [52]. Although some studies have shown more accurate measurements with contrast-enhanced MRA compared with noncontrast MRA, other studies have shown an equal ability to detect aortic pathology and to measure aortic size [44,50,51].

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Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up

A 2014 study comparing thoracic aortic measurements and pathology in 76 patients undergoing both contrast- and noncontrast-enhanced MRA showed high agreement between study types, with low intra- and interobserver dependency (intraclass correlation coefficient 0.99) [51]. A similar 2017 study comparing thoracic aorta measurements/findings on contrast- and noncontrast-enhanced MRA performed on a group of 50 patients favored noncontrast-enhanced MRA over contrast-enhanced MRA as the technique of choice because of superior image quality and better vessel sharpness in the ascending aorta [44]. Although these existing studies focus on the thoracic or abdominal segments of the aorta rather than the thoracoabdominal aorta, findings can likely be extrapolated to the thoracoabdominal aorta. MRA Chest and Abdomen Without and With IV Contrast Compared with MRA of the chest, abdomen, and pelvis, exclusion of the pelvis carries the benefit of faster acquisition time. However, extension to the abdomen without the pelvis involved, results in limited evaluation of the iliofemoral vessels to evaluate suitability for possible endovascular intervention or for aneurysm dilation/dissection of the iliac or femoral arteries if pathology extends to the bifurcation. Thoracoabdominal Aortic Aneurysm or Dissection MRA Chest and Abdomen Without IV Contrast Compared with MRA of the chest, abdomen, and pelvis, exclusion of the pelvis carries the benefit of faster acquisition time. However, extension to the abdomen without inclusion of the pelvis involved results in limited evaluation of the iliofemoral vessels to evaluate suitability for possible endovascular intervention or for aneurysm dilation/dissection of the iliac or femoral arteries if pathology extends to the bifurcation. Radiography Chest Chest radiographs demonstrate abnormalities in a large percentage of patients with acute thoracoabdominal pathology.

Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. A 2014 study comparing thoracic aortic measurements and pathology in 76 patients undergoing both contrast- and noncontrast-enhanced MRA showed high agreement between study types, with low intra- and interobserver dependency (intraclass correlation coefficient 0.99) [51]. A similar 2017 study comparing thoracic aorta measurements/findings on contrast- and noncontrast-enhanced MRA performed on a group of 50 patients favored noncontrast-enhanced MRA over contrast-enhanced MRA as the technique of choice because of superior image quality and better vessel sharpness in the ascending aorta [44]. Although these existing studies focus on the thoracic or abdominal segments of the aorta rather than the thoracoabdominal aorta, findings can likely be extrapolated to the thoracoabdominal aorta. MRA Chest and Abdomen Without and With IV Contrast Compared with MRA of the chest, abdomen, and pelvis, exclusion of the pelvis carries the benefit of faster acquisition time. However, extension to the abdomen without the pelvis involved, results in limited evaluation of the iliofemoral vessels to evaluate suitability for possible endovascular intervention or for aneurysm dilation/dissection of the iliac or femoral arteries if pathology extends to the bifurcation. Thoracoabdominal Aortic Aneurysm or Dissection MRA Chest and Abdomen Without IV Contrast Compared with MRA of the chest, abdomen, and pelvis, exclusion of the pelvis carries the benefit of faster acquisition time. However, extension to the abdomen without inclusion of the pelvis involved results in limited evaluation of the iliofemoral vessels to evaluate suitability for possible endovascular intervention or for aneurysm dilation/dissection of the iliac or femoral arteries if pathology extends to the bifurcation. Radiography Chest Chest radiographs demonstrate abnormalities in a large percentage of patients with acute thoracoabdominal pathology.

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