Mapping of Time-Dependent Myelin Changes in Multiple Sclerosis Lesions through Quantitative Separation of Magnetic Susceptibility Sources

De- and remyelination are important treatment targets for multiple sclerosis therapies. In this study, we utilize susceptibility source separation to study differences in longitudinal trajectories of two important lesion types, paramagnetic rim lesions (rim+) and non-rim (rim-) lesions. We report significant difference in myelin content: while rim- lesions tend to demonstrate slow remyelination, rim+ tend to remain stable or demyelinate over time.