document: Time-resolved contrast-enhanced imaging with isotropic resolution and broad coverage using an undersampled 3D projection trajectory Time-resolved contrast-enhanced 3D MR angiography -LRB- MRA -RRB- methods have gained in popularity but are still limited by the tradeoff between spatial and temporal resolution . A method is presented that greatly reduces this tradeoff by employing undersampled 3D projection reconstruction trajectories . The variable density k-space sampling intrinsic to this sequence is combined with temporal k-space interpolation to provide time frames as short as 4 s . This time resolution reduces the need for exact contrast timing while also providing dynamic information . Spatial resolution is determined primarily by the projection readout resolution and is thus isotropic across the FOV , which is also isotropic . Although undersampling the outer regions of k-space introduces aliased energy into the image , which may compromise resolution , this is not a limiting factor in high-contrast applications such as MRA . Results from phantom and volunteer studies are presented demonstrating isotropic resolution , broad coverage with an isotropic field of view -LRB- FOV -RRB- , minimal projection reconstruction artifacts , and temporal information . In one application , a single breath-hold exam covering the entire pulmonary vasculature generates high-resolution , isotropic imaging volumes depicting the bolus passage
doc_bio_tags: O O O O B I O B I O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O B I O O B I I I O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O B I
extractive_keyphrases: isotropic resolution broad coverage undersampled 3d projection trajectory isotropic field of view pulmonary vasculature bolus passage
abstractive_keyphrases: time-resolved contrast-enhanced imaging 3d mri angiography variable density k-space sampling temporal k-space interpolation abdomen thorax image artifacts breath-hold imaging