title: Diffusion indices on magnetic resonance imaging and neuropsychological performance in amnestic mild cognitive impairment.
abstract: BACKGROUND
  Magnetic resonance diffusion tensor imaging (DTI) shows promise in the early detection of microstructural pathophysiological changes in the brain.
  
  
  OBJECTIVE
  To measure microstructural differences in the brains of participants with amnestic mild cognitive impairment (MCI) compared with an age-matched control group using an optimised DTI technique with fully automated image analysis tools and to investigate the correlation between diffusivity measurements and neuropsychological performance scores across groups.
  
  
  METHODS
  34 participants (17 participants with MCI, 17 healthy elderly adults) underwent magnetic resonance imaging (MRI)-based DTI. To control for the effects of anatomical variation, diffusion images of all participants were registered to standard anatomical space. Significant statistical differences in diffusivity measurements between the two groups were determined on a pixel-by-pixel basis using gaussian random field theory.
  
  
  RESULTS
  Significantly raised mean diffusivity measurements (p<0.001) were observed in the left and right entorhinal cortices (BA28), posterior occipital-parietal cortex (BA18 and BA19), right parietal supramarginal gyrus (BA40) and right frontal precentral gyri (BA4 and BA6) in participants with MCI. With respect to fractional anisotropy, participants with MCI had significantly reduced measurements (p<0.001) in the limbic parahippocampal subgyral white matter, right thalamus and left posterior cingulate. Pearson's correlation coefficients calculated across all participants showed significant correlations between neuropsychological assessment scores and regional measurements of mean diffusivity and fractional anisotropy.
  
  
  CONCLUSIONS
  DTI-based diffusivity measures may offer a sensitive method of detecting subtle microstructural brain changes associated with preclinical Alzheimer's disease.
authors.affiliation: Centre for Magnetic Resonance, University of Queensland, Brisbane 4072, Australia. Stephen.Rose@cmr.uq.edu.au
authors.forename: S E
authors.initials: SE
authors.lastname: Rose
authors.forename: K L
authors.initials: KL
authors.lastname: McMahon
authors.forename: A L
authors.initials: AL
authors.lastname: Janke
authors.forename: B
authors.initials: B
authors.lastname: O'Dowd
authors.forename: G
authors.initials: G
authors.lastname: de Zubicaray
authors.forename: M W
authors.initials: MW
authors.lastname: Strudwick
authors.forename: J B
authors.initials: JB
authors.lastname: Chalk
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000473:pathology; D000647:Amnesia / Q000473:pathology* / Q000523:psychology; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D003072:Cognition Disorders / Q000473:pathology* / Q000523:psychology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008609:Mental Status Schedule