In-vivo submillimeter 3D diffusion MRI for high-resolution, SNR-efficient microstructure imaging

Motivation: Submillimeter diffusion MRI (dMRI) is desirable for neuroscientific research but challenging to achieve in-vivo. Goal(s): To achieve high-quality submillimeter dMRI in-vivo with sufficient SNR and limited blurring and distortion for delineating fine anatomical features. Approach: We use in-plane segmented 3D multi-slab EPI for SNR-efficient dMRI with minimal blurring and distortion, alongside a denoiser-regularized reconstruction that enhances SNR while preserving image fidelity. Results: High-fidelity, high-SNR in-vivo submillimeter whole-brain dMRI at 0.5-0.6mm isotropic resolution is achieved on a 3T clinical scanner. Our experiments demonstrate that the submillimeter data resolve finer microstructure, reduce "gyral bias", and improve U-fiber mapping compared to conventional 1.22mm 3D multi-slab dMRI. Impact: Our study achieves in-vivo submillimeter whole-brain 3D dMRI with minimal blurring, distortion and high SNR. Our approach holds promise in broadly providing more detailed depictions on human brain microstructure and connectivity.