title: Evidence of white matter tract disruption in MRI hyperintensities.
abstract: BACKGROUND
  Diffusion tensor imaging (DTI) of brain tissue measures the apparent diffusion coefficient (ADC), or isotropic diffusion, and anisotropy, or diffusion as influenced by tissue structure. We hypothesized that hyperintensities, when compared with normal tissue by DTI, would show evidence of damage through an increased ADC and decreased anisotropy. We also hypothesized that DTI changes in hyperintensities would be similar between depressed subjects and control subjects.
  
  
  METHODS
  Fourteen depressed geriatric patients and nineteen control subjects received DTI. The ADC and aniso-tropy of normal tissue from standard regions were compared with hyperintensities from these regions. The Students' t test compared individual regions and averaged white matter results.
  
  
  RESULTS
  Hyperintensities showed higher ADC and lower anisotropy than normal regions. Gray matter exhibited similar trends. There was no significant difference in diffusion characteristics of hyperintensities between subjects and control subjects.
  
  
  CONCLUSIONS
  Hyperintensities damage the structure of brain tissue, and do so comparably in depressed subjects and control subjects.
authors.affiliation: Department of Psychiatry, Duke University, Durham, North Carolina 27710, USA.
authors.forename: W D
authors.initials: WD
authors.lastname: Taylor
authors.forename: M E
authors.initials: ME
authors.lastname: Payne
authors.forename: K R
authors.initials: KR
authors.lastname: Krishnan
authors.forename: H R
authors.initials: HR
authors.lastname: Wagner
authors.forename: J M
authors.initials: JM
authors.lastname: Provenzale
authors.forename: D C
authors.initials: DC
authors.lastname: Steffens
authors.forename: J R
authors.initials: JR
authors.lastname: MacFall
mesh_terms: D000368:Aged; D016880:Anisotropy; D001921:Brain / Q000033:anatomy & histology* / Q000473:pathology*; D003866:Depressive Disorder / Q000175:diagnosis / Q000523:psychology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012720:Severity of Illness Index