A longitudinal MRI study of histopathologically defined hypointense multiple sclerosis lesions

Severe tissue destruction is the presumed histopathological correlate of hy pointense multiple sclerosis (MS) lesions. In this study we correlated chan ges of lesion hypointensity over time with initial histopathological featur es in 14 biopsied MS lesions. The extent of hypointensity increased in init ially demyelinated plaques and decreased in remyelinating lesions. The init ial axonal loss determined the increase of hypointensity over time. In conc lusion, both axonal loss and demyelinating activity determine the evolution of hypointensity over time.