title: White matter changes in multiple sclerosis: correlation of q-space diffusion MRI and 1H MRS.
abstract: OBJECTIVE
  To explore the diagnostic usefulness of high b-value diffusion magnetic resonance brain imaging ("q-space" imaging) in multiple sclerosis (MS). More specifically, we aimed at evaluating the ability of this methodology to identify tissue damage in the so-called normal-appearing white matter (NAWM).
  
  
  METHODS
  In this study we examined the correlation between q-space diffusion imaging and magnetic resonance spectroscopy (MRS)-based two-dimensional 1H chemical shift imaging. Eight MS patients with different degree of disease severity and seven healthy subjects were scanned in a 1.5-T magnetic resonance imaging (MRI) scanner. The MRI protocol included diffusion tensor imaging (DTI) (with bmax of 1000 s/mm2), high b-value diffusion-weighted imaging (with bmax of 14,000 s/mm2) and 2D chemical shift imaging. The high b-value data set was analyzed using the q-space methodology to produce apparent displacement and probability maps.
  
  
  RESULTS
  We found that the q-space diffusion displacement and probability image intensities correlated well with N-acetylaspartate levels (r=.61 and .54, respectively). Furthermore, NAWM that was abnormal on MRS was also found to be abnormal using q-space diffusion imaging. In these areas, the q-space displacement values increased from 3.8+/-0.2 to 4.6+/-0.6 microm (P<.02), the q-space probability values decreased from 7.4+/-0.3 to 6.8+/-0.3 (P<.002), while DTI revealed only a small, but still significant, reduction in fractional anisotropy values from 0.40+/-0.02 to 0.37+/-0.02 (P<.05).
  
  
  CONCLUSIONS
  High b-value diffusion imaging can detect tissue damage in the NAWM of MS patients. Despite the theoretical limitation of this method, in practice it provides additional information which is clinically relevant for detection of tissue damage not seen in conventional imaging techniques.
authors.affiliation: Functional Brain Imaging Laboratory, Tel Aviv Sourasky Medical Center, Tel Aviv 64239, Israel. assafyan@post.tau.ac.il
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Assaf
authors.forename: Joab
authors.initials: J
authors.lastname: Chapman
authors.forename: Dafna
authors.initials: D
authors.lastname: Ben-Bashat
authors.forename: Talma
authors.initials: T
authors.lastname: Hendler
authors.forename: Yoram
authors.initials: Y
authors.lastname: Segev
authors.forename: Amos D
authors.initials: AD
authors.lastname: Korczyn
authors.forename: Moshe
authors.initials: M
authors.lastname: Graif
authors.forename: Yoram
authors.initials: Y
authors.lastname: Cohen
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index
chemical_list: D011522:Protons