Contrast-enhanced MR angiography using time resolved interleaved projection sampling with three-dimensional Cartesian phase and slice encoding (TRIPPS).

Undersampled projection reconstruction (PR) techniques provide contrast enhanced MR angiography (CE-MRA) with high temporal resolution, but sensitivity to eddy current, gradient error and off-resonance effects. It is desirable to combine the time efficiency of undersampled PR acquisition with the robustness of Cartesian imaging. In this work we present a technique designed to do this termed time resolved projection sampling with three-dimensional (3D) Cartesian phase and slice encoding (TRIPPS), where 3D Cartesian k-space is partitioned into multiple half projections in the ky-kz plane. The phase and slice encoding are performed along predefined center-out radial trajectories. The whole set of half projections is interleaved into multiple groups of half projections, with each group sparsely but uniformly covering the ky-kz space. A view sharing sliding window reconstruction algorithm is adapted to reconstruct the dynamic images. The feasibility of the TRIPPS technique for CE-MRA was demonstrated on the renal, pulmonary, and intracranial vasculatures of healthy volunteers with a high temporal resolution of 2 s/frame.