title: Diffusion abnormality in posterior cingulate fiber tracts in Alzheimer's disease: tract-specific analysis.
abstract: OBJECTIVE
  The aim of this study was to determine diffusion abnormalities in the posterior cingulate fiber tracts (PCFTs) in patients with Alzheimer's disease (AD) by diffusion tensor tractography (DTT).
  
  
  METHODS
  We studied 23 AD patients and 18 age-matched normal controls who underwent magnetic resonance imaging using diffusion tensor imaging (DTI). DTT of PCFTs was generated from DTI. Mean diffusivity (MD) and fractional anisotropy (FA) were measured in co-registered voxels along with DTT of PCFTs. Student's t-test was used to compare results between the AD patients and normal controls.
  
  
  RESULTS
  The MD in PCFTs was significantly higher in AD patients than in normal controls (P = 0.019). The FA in PCFTs was significantly lower in AD patients than in normal controls (P = 0.007).
  
  
  CONCLUSIONS
  The abnormal MD increase and FA decrease, which is considered to indicate a net loss of barriers that restrict water molecular motion and tissue anisotropy of white matter, is consistent with neuropathological data that demonstrate partial loss of myelin, axons, and oligodendrial cells in white matter of AD brains. Our results suggest that MD and FA reflect progression of AD-related histopathological changes in the PCFTs and may represent a useful biological index for monitoring AD.
authors.affiliation: Department of Radiology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. nakatay-tky@umin.ac.jp
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nakata
authors.forename: Noriko
authors.initials: N
authors.lastname: Sato
authors.forename: Osamu
authors.initials: O
authors.lastname: Abe
authors.forename: Shoko
authors.initials: S
authors.lastname: Shikakura
authors.forename: Kunimasa
authors.initials: K
authors.lastname: Arima
authors.forename: Nobuo
authors.initials: N
authors.lastname: Furuta
authors.forename: Masatake
authors.initials: M
authors.lastname: Uno
authors.forename: Shigeo
authors.initials: S
authors.lastname: Hirai
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Masutani
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
authors.forename: Shigeki
authors.initials: S
authors.lastname: Aoki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000378:metabolism*; D016880:Anisotropy; D001369:Axons / Q000378:metabolism / Q000473:pathology; D016022:Case-Control Studies; D004058:Diffusion; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006179:Gyrus Cinguli / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009413:Nerve Fibers, Myelinated / Q000378:metabolism / Q000473:pathology; D009836:Oligodendroglia / Q000378:metabolism / Q000473:pathology; D011712:Pyramidal Tracts / Q000378:metabolism / Q000473:pathology; D012720:Severity of Illness Index