The effects of magnetization transfer on fast and slow diffusion compartments in myelinated white matter

Myelin, although not directly visible in conventional diffusion MRI (dMRI) due to its short T2, still affects the dMRI signal indirectly through exchange processes with nearby water compartments. In this study, we investigated how a magnetization transfer (MT) preparation affects dMRI signals, in particular, the fast and slow diffusion compartments in myelinated white matter of ex vivo mouse brain. Our result demonstrated that the MT preparation altered the volume fractions, but not the diffusivities, of the fast and slow compartments. Examining the change in volume fractions with MT preparation can provide insights into exchange processes involving myelin and water compartments.