title: Change of diffusion anisotropy in patients with acute cerebral infarction using statistical parametric analysis.
abstract: OBJECTIVE
  We conducted statistical parametric comparison of fractional anisotropy (FA) images and quantified FA values to determine whether significant change occurs in the ischemic region.
  
  
  METHODS
  The subjects were 20 patients seen within 24 h after onset of ischemia. For statistical comparison of FA images, a sample FA image was coordinated by the Talairach template, and each FA map was normalized. Statistical comparison was conducted using SPM99. Regions of interest were set in the same region on apparent diffusion coefficient (ADC) and FA maps, the region being consistent with the hyperintense region on diffusion-weighted images (DWIs). The contralateral region was also measured to obtain asymmetry ratios of ADC and FA.
  
  
  RESULTS
  Regions with areas of statistical significance on FA images were found only in the white matter of three patients, although the regions were smaller than hyperintense regions on DWIs. The mean ADC and FA ratios were 0.64 +/- 0.16 and 0.93 +/- 0.09, respectively, and the degree of FA change was less than that of the ADC change. Significant change in diffusion anisotropy was limited to the severely infarcted core of the white matter.
  
  
  CONCLUSIONS
  We believe statistical comparison of FA maps to be useful for detecting different regions of diffusion anisotropy.
authors.affiliation: Department of Radiology, School of Medicine, University of Tokushima, Tokushima, Japan. nmorita@clin.med.tokushima-u.ac.jp
authors.forename: Naomi
authors.initials: N
authors.lastname: Morita
authors.forename: Masafumi
authors.initials: M
authors.lastname: Harada
authors.forename: Masaaki
authors.initials: M
authors.lastname: Uno
authors.forename: Kaori
authors.initials: K
authors.lastname: Furutani
authors.forename: Hiromu
authors.initials: H
authors.lastname: Nishitani
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016880:Anisotropy; D002544:Cerebral Infarction / Q000175:diagnosis*; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity