title: MRI quantification of gray and white matter damage in patients with early-onset multiple sclerosis.
abstract: OBJECTIVE
  Contrary to what happens in adult-onset multiple sclerosis (MS), in a previous preliminary magnetic resonance imaging (MRI) study we showed only subtle normal-appearing brain tissue changes in patients with earlyonset MS. Our objective was to evaluate the presence and extent of tissue damage in the brain normalappearing white matter (NAWM) and gray matter (GM) from a larger population of patients with earlyonset MS.
  
  
  METHODS
  Using diffusion tensor (DT) and magnetization transfer (MT) MRI, we obtained DT and MT ratio (MTR) maps of the NAWM and GM from 23 patients with early-onset MS and 16 sex- and age-matched healthy volunteers.
  
  
  RESULTS
  Compared with healthy volunteers, patients with early-onset MS had significantly increased average MD (p = 0.02) and FA peak height (p = 0.007) and decreased average FA (p <0.0001) of the NAWM. Brain dual-echo lesion load was significantly correlated with average FA (r = -0.48, p = 0.02) and with FA peak height (r = 0.45, p = 0.03) of the NAWM. No MTR and diffusion changes were detected in the GM.
  
  
  CONCLUSIONS
  This study confirms the paucity of the 'occult' brain tissue damage in patients with earlyonset MS. It also suggests that in these patients GM is spared by the disease process and that NAWM changes are likely to be secondary to Wallerian degeneration of fibers passing through macroscopic lesions.
authors.affiliation: Neuroimaging Research Unit Department of Neurology, Scientific Institute and University Ospedale San Raffaele, Via Olgettina, 60, 20132, Milan, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Tortorella
authors.forename: M A
authors.initials: MA
authors.lastname: Rocca
authors.forename: D M
authors.initials: DM
authors.lastname: Mezzapesa
authors.forename: A
authors.initials: A
authors.lastname: Ghezzi
authors.forename: L
authors.initials: L
authors.lastname: Lamantia
authors.forename: G
authors.initials: G
authors.lastname: Comi
authors.forename: M
authors.initials: M
authors.lastname: Filippi
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D001921:Brain / Q000473:pathology* / Q000503:physiopathology; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D018450:Disease Progression; D005260:Female; D005911:Gliosis / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009103:Multiple Sclerosis / Q000473:pathology* / Q000503:physiopathology; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009434:Neural Pathways / Q000473:pathology* / Q000503:physiopathology; D011237:Predictive Value of Tests; D017678:Sex Distribution; D014855:Wallerian Degeneration / Q000209:etiology / Q000473:pathology / Q000503:physiopathology