title: Application of voxelwise analysis in the detection of regions of reduced fractional anisotropy in multiple sclerosis patients.
abstract: OBJECTIVE
  To investigate the utility of voxelwise analysis in the detection of lesions in the normal appearing white matter (NAWM) of individual multiple sclerosis (MS) patients.
  
  
  METHODS
  Diffusion tensor imaging (DTI) was performed on 10 normal controls and six patients with MS lesions. The fractional anisotropy (FA) maps derived from the diffusion-weighted images were then spatially normalized (via an affine transformation) into Montreal Neurological Institute (MNI) space, and the normalized FA map of each of the patients was compared voxelwise with the normalized FA maps of the group of normals in a one-sample t-test (P = 0.0001). Two independent board-certified neuroradiologists reviewed the data.
  
  
  RESULTS
  In the patient data for all six cases, the two reviewers determined detection sensitivities of 72% and 96% for the voxelwise technique based on known fluid-attenuated inversion-recovery (FLAIR) lesions. In addition, between the two reviewers, nine NAWM regions exhibiting FA reductions were identified in the six patients. However, numerous regions of abnormal FA were detected that were attributed to poor intersubject image registration.
  
  
  CONCLUSIONS
  Voxelwise analysis of spatially normalized FA maps has the potential to identify regions of FA reduction in lesions and in the NAWM of individual MS patients in a rapid and reproducible fashion. J. Magn. Reson. Imaging 2007;26:552-556. (c) 2007 Wiley-Liss, Inc.
authors.affiliation: Department of Biomedical Engineering, Drexel University, Philadelphia, Pennsylvania, USA.
authors.forename: Sunil A
authors.initials: SA
authors.lastname: Patel
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Hum
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Gonzalez
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schwartzman
authors.forename: Scott H
authors.initials: SH
authors.lastname: Faro
authors.forename: Feroze B
authors.initials: FB
authors.lastname: Mohamed
mesh_terms: D000328:Adult; D016880:Anisotropy; D001921:Brain / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008875:Middle Aged; D015233:Models, Statistical; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D009462:Neurology / Q000379:methods; D011859:Radiography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity