Advanced Diffusion Imaging Methods to Assess the Microstructure of Multiple Sclerosis Lesions

Paramagnetic Rim Lesions (PRL) in Multiple Sclerosis (MS) are associated with increased disability and axonal damage. We examined PRL microstructure using Track Density Imaging (TDI) and four diffusion MRI (dMRI) models, including Microstructure Fingerprinting (MF). When compared to non-PRL, PRL showed larger size, higher T1-values, lower neurite density index and fibre volume fraction on dMRI (p < 0.001) and reduced track density on TDI (p < 0.0001), suggesting impaired axonal density/integrity in PRL. Results obtained with the novel MF model are in line with those obtained with other dMRI models, indicating its potential for studying MS lesion pathology.