title: Magnetic resonance spectroscopic findings of chronic lesions in two subtypes of multiple sclerosis: primary progressive versus relapsing remitting.
abstract: BACKGROUND
  Multiple sclerosis (MS) is a highly prevalent cause of neurological disability and has different clinical subtypes with potentially different underlying pathologies. Differentiation of primary progressive multiple sclerosis (PPMS) from relapsing remitting multiple sclerosis (RRMS) could be difficult especially in its early phases.
  
  
  OBJECTIVE
  We compared brain metabolite concentrations and ratios in patients with PPMS and RRMS by magnetic resonance spectroscopic imaging (MRSI).
  
  
  METHODS
  Thirty patients with definite MS (15 with RRMS and 15 with PPMS) underwent MRSI and their non-enhancing lesion metabolites were measured. N-acetyl aspartate (NAA), Creatine (Cr), Choline (Cho), NAA/Cr and NAA/Cho were measured and compared between the two MS subtypes.
  
  
  RESULTS
  When the two MS groups were compared together, we found that Cr was significantly increased (P value=0.008) and NAA/Cr was significantly decreased (P value=0.03) in non-enhancing lesions in PPMS compared with RRMS. There was no significant difference in NAA, Cho or NAA/Cho between the two MS subtypes.
  
  
  CONCLUSIONS
  MRS is a potential way to differentiate PPMS and RRMS.
authors.affiliation: Iranian Center of Neurological Research, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Nasrin
authors.initials: N
authors.lastname: Rahimian
authors.affiliation: Quantitative MR Imaging and Spectroscopy Group, Research Center for Cellular and Molecular Imaging, Medical Physics and Biomedical Engineering Department, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Saligheh Rad
authors.affiliation: Advanced Diagnostic and Interventional Radiology Research Center (ADIR), Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Kavous
authors.initials: K
authors.lastname: Firouznia
authors.affiliation: Department of Radiology, Shohada-e-Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Seyed Amir
authors.initials: SA
authors.lastname: Ebrahimzadeh
authors.affiliation: Community Medicine Department, Medical Faculty, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Alipasha
authors.initials: A
authors.lastname: Meysamie
authors.affiliation: Quantitative MR Imaging and Spectroscopy Group, Research Center for Cellular and Molecular Imaging, Medical Physics and Biomedical Engineering Department, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Hamideh
authors.initials: H
authors.lastname: Vafaiean
authors.affiliation: Iranian Center of Neurological Research, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Harirchian
keywords: Magnetic Resonance Spectroscopy; Multiple Sclerosis, Chronic Progressive; Multiple Sclerosis, Relapsing-Remitting