title: Imaging of repeated episodes of demyelination and remyelination in multiple sclerosis.
abstract: Multiple sclerosis (MS) is characterized by the formation of demyelinating lesions in the white matter (WM). However, the timecourse of the evolution of healthy white matter into fully demyelinated lesions in MS is not well understood. We use a recently proposed technique to examine magnetization transfer ratio (MTR) timecourses in lesions segmented from MTR images in patients with relapsing-remitting MS (RRMS) and secondary progressive MS (SPMS). In both groups we found MTR lesions forming both in previously normal appearing WM (de novo lesions) as well as in previously lesional tissue that appears to be experiencing a second round of inflammatory demyelination (repeat lesions). Both de novo and repeat lesions exhibited significant, but incomplete MTR recovery, suggesting partial remyelination; post-lesion MTR values in de novo lesions were similar to pre-lesion values in repeat lesions. Both de novo and repeat lesions were found in subjects in relapsing-remitting and secondary progressive stages of MS, and repeat lesions appeared relatively more common in the secondary progressive phase. These observations support the hypothesis that entirely demyelinated lesions found on histopathology are the result of multiple episodes of demyelination and incomplete remyelination, and may have implications for MS treatment development efforts aimed at neuroprotection and enhancing remyelination.
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, 3801 Rue University, Montreal H3A 2B4, Canada.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Brown
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, 3801 Rue University, Montreal H3A 2B4, Canada.
authors.forename: Sridar
authors.initials: S
authors.lastname: Narayanan
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, 3801 Rue University, Montreal H3A 2B4, Canada.
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Arnold
mesh_terms: D000328:Adult; D000368:Aged; D003711:Demyelinating Diseases / Q000473:pathology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology*; D009186:Myelin Sheath / Q000473:pathology*; D013997:Time Factors; D066127:White Matter / Q000473:pathology*; D055815:Young Adult
keywords: Magnetic resonance imaging; Magnetization transfer ratio; Multiple sclerosis; Remyelination