High-Resolution, Volumetric Diffusion-Weighted MR Spectroscopic Imaging of the Brain

Motivation: Diffusion-weighted MRSI (DW-MRSI) is a potentially powerful microstructural imaging tool. Goal(s): To achieve high-resolution, 3D DW-MRSI of the brain in clinically relevant times. Approach: Novel fast DW-MRSI acquisition, excitation-resolved phase navigation, and computational strategies combining subspace imaging and machine-learning-assisted reconstruction and quantification were proposed and integrated. Results: Experimental results demonstrated the consistency of metabolite-specific diffusion estimates between conventional and our methods, with the latter achieving more than 20X resolution improvement, 3D coverage, and good reproducibility. 3D multi-molecular mean diffusivity maps can be obtained at a 6.9x6.9x7.0mm3 resolution, and high-resolution (4.4x4.4x5.6mm3) metabolite ADC maps can be obtained within 20 mins for the first time. Impact: Our technology enabled an unprecedented capability of high-resolution, 3D metabolite-specific diffusion parameter mapping. This capability has significant potential to offer tissue-compartment- and cell-type-specific microstructural information in vivo for many clinical and neuroscience applications.