title: Pathologic damage in MS assessed by diffusion-weighted and magnetization transfer MRI.
abstract: OBJECTIVE
  To compare diffusion characteristics of MS lesions, normal-appearing white matter (NAWM) from patients, and normal white matter from control subjects, and to investigate the correlations between the magnetization transfer ratio (MTR) and a directionally averaged tissue water diffusion coefficient (D) in patients.
  
  
  BACKGROUND
  MS and other pathologic processes that modify tissue integrity can result in abnormal diffusion of water molecules detectable by diffusion-weighted imaging (DWI).
  
  
  METHODS
  Conventional dual-echo and DWI scans were obtained from 35 patients with relapsing-remitting MS and 24 healthy control subjects. MT scans were also obtained from the patients. After coregistration of all scans, MTR and D values from MS lesions and NAWM in different regions were marked using the dual-echo scans as a reference. D values from the same brain regions in control subjects were acquired. Histograms of MTR and D were also produced.
  
  
  RESULTS
  Patients with MS had significantly higher D values in all the areas studied. Moreover, histogram metrics (peak height, peak site, and average D) from patients were substantially different from those of control subjects. In patients, average lesion D and MTR were markedly different from those in the NAWM. There was an inverse correlation between average lesion MTR and D inside lesions, whereas no correlation was found for average MTR and D taken from the histograms.
  
  
  CONCLUSIONS
  DWI detects severe tissue disruption inside lesions and subtle widespread abnormalities in NAWM in patients with relapsing-remitting MS. MT and DWI may provide information about different aspects of brain pathology in MS.
authors.affiliation: Department of Neuroscience, Scientific Institute Ospedale San Raffaele, University of Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cercignani
authors.forename: G
authors.initials: G
authors.lastname: Iannucci
authors.forename: M A
authors.initials: MA
authors.lastname: Rocca
authors.forename: G
authors.initials: G
authors.lastname: Comi
authors.forename: M A
authors.initials: MA
authors.lastname: Horsfield
authors.forename: M
authors.initials: M
authors.lastname: Filippi
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009103:Multiple Sclerosis / Q000473:pathology*