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.
Li et al. (Tue,) studied this question.