title: Relevance of the skewness index in DTI exploration of multiple sclerosis.
abstract: OBJECTIVE
  To this day, no parameter can really monitor the progression of multiple sclerosis (MS). In this study, an index the skewness (S) derived from parameters calculated in diffusion tensor imaging (DTI) has been tested on MS patients for its ability to monitor the disease course.
  
  
  METHODS
  Eighteen patients underwent two examinations within 3 months consisting of a clinical evaluation (EDSS) and DTI acquisitions on a 1.5 T imager. Tensor was calculated thanks to"home-made" software. Mean diffusivity (MD) and fractional anisotropy (FA) histograms were described for normal-appearing white matter (NAWM) and gray matter (GM) of patients with S and also with usually indices peak position (pp) and peak height (ph) for the whole group of patients and for two separate groups according to their clinical status (EDSS < or = 3 and EDSS > 3 at month 0).
  
  
  RESULTS
  Although no significant clinical evolution is observed over 3 months, S in GM showed a significant shift for both MD/FA histograms towards abnormal values for the whole group of patients (p = 0.02/p = 0.04) and for the group with EDSS </= 3 (p = 0.04/p = 0.007), while ph and pp do not.
  
  
  CONCLUSIONS
  S in GM could be an alternative marker to monitor the disease course before the repercussion on the clinical score.
authors.affiliation: Department of Biophysics, University Hospital of Rangueil, 31059 Toulouse, France. graulieres@hotmail.com
authors.forename: Eliane
authors.initials: E
authors.lastname: Graulières
authors.forename: Jean-Albert
authors.initials: JA
authors.lastname: Lotterie
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Cassol
authors.forename: Angélique
authors.initials: A
authors.lastname: Gerdelat
authors.forename: Michel
authors.initials: M
authors.lastname: Clanet
authors.forename: Isabelle
authors.initials: I
authors.lastname: Berry
mesh_terms: D000328:Adult; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D009103:Multiple Sclerosis / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique