Accelerated Diffusion-Weighted MRI at 7T: Joint Reconstruction for Shift-Encoded Navigated Interleaved Echo Planar Imaging (JETS-NAViEPI)

Motivation: Diffusion-weighted MRI suffers from limited spatial resolution, residual geometric distortion, and long acquisition. Goal(s): To develop high spatial-angular-temporal resolution DW-MRI at 7T. Approach: We developed ky-shift encoding and navigated interleaved EPI (NAViEPI) with consistent echo spacing, enabling efficient sampling and minimal distortion mismatch between echoes. We developed joint reconstruction with locally low-rank regularization, encompassing multi-band slices and multiple diffusion directions. Results: We achieved (1) whole brain 3-scan trace acquisition at a resolution of 0.5 x 0.5 x 2.0 mm3 and 98 seconds, and (2) 3-shell 126 diffusion encodings with 1.0 mm isotropic resolution and 22 minutes scan time. Impact: JETS-NAViEPI enables accelerated submillimeter resolution in vivo brain DW-MRI at 7T, offering both clinically relevant 3-scan trace and neuroscientific DTI protocols.