title: Longitudinal, region-specific course of diffusion tensor imaging measures in mild cognitive impairment and Alzheimer's disease.
abstract: BACKGROUND
  Diffusion tensor imaging (DTI) is a promising method for identifying significant cross-sectional differences of white-matter tracts in normal controls (NC) and those with mild cognitive impairment (MCI) or Alzheimer's disease (AD). There have not been many studies establishing its longitudinal utility.
  
  
  METHODS
  Seventy-five participants (25 NC, 25 amnestic MCI, and 25 AD) had 3-Tesla MRI scans and clinical evaluations at baseline and 3, 6, and 12 months. Fractional anisotropy (FA) and mean diffusivity (MD) were analyzed at each time-point and longitudinally in eight a priori-selected areas taken from four regions of interest (ROIs).
  
  
  RESULTS
  Cross-sectionally, MD values were higher, and FA values lower in the fornix and splenium of the AD group compared with either MCI or NC (P < .01). Within-group change was more evident in MD than in FA over 12 months: MD increased in the inferior, anterior cingulum, and fornix in both the MCI and AD groups (P < .01).
  
  
  CONCLUSIONS
  There were stable, cross-sectional, region-specific differences between the NC and AD groups in both FA and MD at each time-point over 12 months. Longitudinally, MD was a better indicator of change than FA. Significant increases of fornix MD in the MCI group suggest this is an early indicator of progression.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine and Johns Hopkins Bayview Medical Center, Baltimore, MD, USA. mnowran1@jhmi.edu
authors.forename: Milap A
authors.initials: MA
authors.lastname: Nowrangi
authors.forename: Constantine G
authors.initials: CG
authors.lastname: Lyketsos
authors.forename: Jeannie-Marie S
authors.initials: JM
authors.lastname: Leoutsakos
authors.forename: Kenichi
authors.initials: K
authors.lastname: Oishi
authors.forename: Marilyn
authors.initials: M
authors.lastname: Albert
authors.forename: Susumu
authors.initials: S
authors.lastname: Mori
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Mielke
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000473:pathology*; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D060825:Cognitive Dysfunction / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008137:Longitudinal Studies; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology*