Motivation: Estimating susceptibility-related tissue parameters with MRI in white matter requires imaging at multiple orientations which makes it practically infeasible. Goal(s): This study aims to estimate such anisotropic susceptibility-related parameters without rotating the sample. Approach: We propose a novel model extending The Standard Model of Diffusion to a multi-spin-echo diffusion MRI signal with multiple delayed read-outs per echo. We validate our model (SMPR) using Monte Carlo simulations in realistic white matter axonal microstructures segmented from electron microscopy. Results: The SMPR model effectively estimated all parameters in the intra-axonal space from a single sample orientation. Impact: Modeling a multi-spin-echo diffusion MRI signal with delayed read-outs per echo enables estimation of orientation-dependent susceptibility parameters without imaging multiple sample orientations. This approach could improve sensitivity to tissue characteristics, aiding studies of myelination and other white matter features.
Sandgaard et al. (Tue,) studied this question.