Evaluation of white matter integrity in multiple sclerosis using ultra-high gradient diffusion imaging

Conventional MRI of multiple sclerosis lacks specificity for the underlying disease-related processes. The use of ultra-high gradient diffusion imaging increases sensitivity for small caliber axons. When used in combination with myelin-sensitive imaging, estimates of axonal volume fraction (AVF), myelin volume fraction (MVF), and the g-ratio can be obtained. Here, we derived estimates of axonal and myelin metrics on a per-voxel basis using ultra-high gradient diffusion MR and macromolecular tissue volume (MTV) in MS patients and healthy controls. Compared to healthy subjects, focal MS lesions and to a lesser extent the normal appearing white matter demonstrated evidence of demyelination and axonal loss.