Measuring intravoxel incoherent motion (IVIM) using Spherical Tensor Encoding (STE) diffusion MRI

Motivation: The assumption of Gaussian diffusion in the extravascular space in the IVIM model does not necessarily hold, especially for neuronal tissues. Goal(s): To mitigate the impacts on IVIM estimation from complicated extravascular space diffusion such as in the crossing-fiber tissues. Approach: We employed Spherical Tensor Encoding (STE) in place of the Linear Tensor Encoding (LTE) as in the conventional Stejskal-Tanner experiment to eliminate the orientational dependence of diffusion signal. Results: The feasibility of the microscopic IVIM based on STE experiments was demonstrated in both healthy and diseased participants, with expected contrasts according to known anatomy/pathology. Impact: A new framework of IVIM measurement was proposed based on the Linear Tensor Encoding diffusion experiment. The proposed approach can achieve diffusivity estimates in one excitation, which will otherwise require acquisition of multiple diffusion weighting directions.