title: Proton MR spectroscopy and magnetization transfer ratio in multiple sclerosis: correlative findings of active versus irreversible plaque disease.
abstract: OBJECTIVE
  To characterize plaques of multiple sclerosis (MS) using both proton MR spectroscopy and magnetization transfer (MT) imaging.
  
  
  METHODS
  The magnetization transfer ratio (MTR) was calculated from two series of three-dimensional gradient-recalled acquisition in the steady state (GRASS) images obtained with and without an MT saturation pulse. Proton spectra were acquired using the point-resolved spectroscopy (PRESS) sequence with a voxel size of 1.5 x 1.5 x 1.5 cm3. A total of 28 spectra were obtained in 13 patients who had clinically definitive MS. The spectra were analyzed together with the MTR.
  
  
  RESULTS
  A positive relationship was found between the N-acetylaspartate (NAA)/creatine (Cr) ratio and the MTR in MS plaques, whereas no significant correlation was found between the metabolite ratios and the signal intensity on fast spin-echo T2-weighted MR images.
  
  
  CONCLUSIONS
  Small changes in the MTR of MS plaques relative to the MTR of normal white matter may reflect inflammatory changes and edema, whereas larger changes in MTR correlate with decreased NAA/Cr ratio and therefore suggest demyelination and irreversible damage from chronic MS plaques.
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: H
authors.initials: H
authors.lastname: Kimura
authors.forename: R I
authors.initials: RI
authors.lastname: Grossman
authors.forename: R E
authors.initials: RE
authors.lastname: Lenkinski
authors.forename: F
authors.initials: F
authors.lastname: Gonzalez-Scarano
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000032:analysis; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001927:Brain Diseases / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D001929:Brain Edema / Q000378:metabolism / Q000473:pathology; D002794:Choline / Q000032:analysis; D002908:Chronic Disease; D003401:Creatine / Q000032:analysis; D003711:Demyelinating Diseases / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D004660:Encephalitis / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D011522:Protons
chemical_list: D011522:Protons; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline