Vastly undersampled Isotropic Projection Reconstruction and HYPR for Time Resolved CE-MRA of the Peripheral Vessels

Introduction Vastly undersampled Isotropic Projection Reconstruction (VIPR) [1] techniques have been successfully utilized for time-resolved contrast-enhanced MR angiography (CE-MRA) studies. There are several benefits of a VIPR k-space trajectory, including the more benign nature of undersampling artifacts, which can facilitate higher undersampling factors. Due to the geometry of the legs, however, and the fact that the A/P extent of the image object is much smaller than the S/I or L/R extents, it has previously been thought that other k-space trajectories are more valuable for such an application. In this work we apply the VIPR k-space trajectory to peripheral runoff studies and apply HYPR LR [2] reconstruction to obtain images with isotropic spatial resolution and temporal resolution superior to those obtained by conventional time-resolved methods and other k-space trajectories. Materials and Methods Mathematically, the HYPR LR reconstruction algorithm can be represented as: