Ischemic stroke: effects of etiology and patient age on the time course of the core apparent diffusion coefficient.
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.
Copen
W A
WA
Harvard Medical School, NMR Center, Massachusetts General Hospital, Boston, MA 02129, USA.
Schwamm
L H
LH
González
R G
RG
Wu
O
O
Harmath
C B
CB
Schaefer
P W
PW
Koroshetz
W J
WJ
Sorensen
A G
AG
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
D014867:Water