title: Magnetization transfer ratio evolution with demyelination and remyelination in multiple sclerosis lesions.
abstract: OBJECTIVE
  To assess demyelination and remyelination in vivo in acute gadolinium (Gd)-enhancing lesions of multiple sclerosis (MS).
  
  
  METHODS
  We measured significant changes in magnetization transfer ratio (MTR) consistent with demyelination and remyelination of individual lesion voxels, as well as the mean normalized MTR over all lesion voxels during and after contrast enhancement, in MS patients participating in a 3-year Canadian trial assessing immunoablation and autologous stem cell transplantation for treatment of MS.
  
  
  RESULTS
  The average mean normalized lesion MTR over all lesions exhibited partial recovery over 2 to 4 months after Gd enhancement. Voxel-based analysis demonstrated that approximately 70% of the initially enhancing lesion volume (GdLV) was left with stably low MTR over 39 months of evaluation. The percentage of the GdLV undergoing significant increases in MTR consistent with remyelination increased for approximately 7 months after enhancement and then stabilized at 21 %GdLV. Significant decreases in MTR consistent with demyelination were ongoing for approximately 33 months after enhancement, stabilizing at 9 %GdLV. The estimated error of these measurements, based on scan/rescan analysis, was less than 0.4 %GdLV.
  
  
  CONCLUSIONS
  We found significant changes in MTR consistent with demyelination and remyelination that followed different temporal evolutions and were ongoing in different lesion regions for at least 3 years after lesion formation.
authors.affiliation: McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada.
authors.forename: Jacqueline T
authors.initials: JT
authors.lastname: Chen
authors.forename: D Louis
authors.initials: DL
authors.lastname: Collins
authors.forename: Harold L
authors.initials: HL
authors.lastname: Atkins
authors.forename: Mark S
authors.initials: MS
authors.lastname: Freedman
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Arnold
mesh_terms: D000328:Adult; D002490:Central Nervous System / Q000473:pathology* / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005682:Gadolinium; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009103:Multiple Sclerosis / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009416:Nerve Regeneration / Q000502:physiology*; D020127:Recovery of Function / Q000502:physiology*; D012720:Severity of Illness Index; D033581:Stem Cell Transplantation; D013997:Time Factors
chemical_list: D005682:Gadolinium