title: Ischemic stroke: effects of etiology and patient age on the time course of the core apparent diffusion coefficient.
abstract: OBJECTIVE
  To determine whether the evolution of the core apparent diffusion coefficient (ADC) of water in ischemic stroke varies with patient age or infarct etiology.
  
  
  METHODS
  One hundred forty-seven patients with stroke underwent 236 diffusion-weighted magnetic resonance imaging examinations. Etiologies of lesions were classified according to predefined criteria; in 224 images, the diagnosis of lacune could be firmly established or excluded. ADC was measured in the center of each lesion and in contralateral normal-appearing brain. A model was used to describe the time course of relative ADC (rADC), which is calculated by dividing the lesion ADC by the contralateral ADC, and to test for age- or etiology-related differences in this time course.
  
  
  RESULTS
  Transition from decreasing to increasing rADC was estimated at 18.5 hours after stroke onset. In subgroup analysis, transition was earlier in nonlacunes than in lacunes (P =.02). There was a trend toward earlier transition in patients older than the median age of 66.0 years, compared with younger patients (P =.06). Pseudonormalization was estimated at 216 hours. Among nonlacunes, the rate of subsequent rADC increase was more rapid in younger patients than in older patients (P =.001). Within the smaller sample of lacunes, however, no significant age-related difference in this rate was found.
  
  
  CONCLUSIONS
  Differences in ADC depending on the patient's age and infarct etiology suggest differing rates of ADC progression.
authors.affiliation: Harvard Medical School, NMR Center, Massachusetts General Hospital, Boston, MA 02129, USA.
authors.forename: W A
authors.initials: WA
authors.lastname: Copen
authors.forename: L H
authors.initials: LH
authors.lastname: Schwamm
authors.forename: R G
authors.initials: RG
authors.lastname: González
authors.forename: O
authors.initials: O
authors.lastname: Wu
authors.forename: C B
authors.initials: CB
authors.lastname: Harmath
authors.forename: P W
authors.initials: PW
authors.lastname: Schaefer
authors.forename: W J
authors.initials: WJ
authors.lastname: Koroshetz
authors.forename: A G
authors.initials: AG
authors.lastname: Sorensen
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000209:etiology* / Q000378:metabolism / Q000473:pathology*; D004058:Diffusion; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000209:etiology* / Q000378:metabolism / Q000473:pathology*; D013997:Time Factors; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water