Predicting Mesoscopic Larmor Frequency Shifts in White Matter with Diffusion MRI -- An In-Silico Monte-Carlo Study

Abstract

This study aims to validate if MRI can measure anisotropic mesoscopic Larmor frequency shifts from white matter axonal microstructure relative to the B0 direction and if dMRI can estimate this anisotropy. Recent models describe how mesoscopic Larmor frequency shifts depend on induced magnetic fields by axons, described by an orientation distribution function. Using Monte-Carlo simulations of MRI signals in mesoscopic white matter axon substrates, we show MRI can estimate this mesoscopic frequency shift and dMRI can estimate its orientation dependence.