Whole-Brain Mesoscale 0.7 millimeter-Isotropic-Resolution Diffusion MRI at Ultra-High Fields: The JETS-NAViEPI Approach.

Motivation: Diffusion weighted MRI (DWI) may blur structures due to limited resolution. Increasing to submillimeter resolution reduces partial volume effects but sacrifices SNR. Goal(s): We seek to demonstrate submillimeter isotropic DWI at 7T in 3 minutes, and enhanced high-resolution DTI maps. Approach: Data acquisition is done via NAViEPI, enforcing consistent echo spacing between the imaging and the navigator echo, rendering minimal distortion mismatch. Image reconstruction is done using JETS, benefiting from complementary k-q-space sampling and regularization. Results: We show a 3-scan trace acquisition with a scan time of 3:19 minutes, and offer high-resolution DTI measurement leading to Mean Diffusivity and colored Fractional Anisotropy maps. Impact: This work demonstrates submillimeter isotropic diffusion MRI at ultra-high field 7T with improved image quality and reduced scan duration. The JETS-NAViEPI method has the potential to advance high-resolution diffusion MRI, enhancing both spatial and temporal resolution.