Apparent diffusion coefficient decreases and magnetic resonance imaging perfusion parameters are associated in ischemic tissue of acute stroke patients
J. Fiehler et al., Apparent diffusion coefficient decreases and magnetic resonance imaging perfusion parameters are associated in ischemic tissue of acute stroke patients, J CEREBR B, 21(5), 2001, pp. 577-584
Perfusion- and diffusion-weighted magnetic resonance imaging scans are thou
ght to allow the characterization of tissue at risk of infarction. The auth
ors tested the hypothesis that the apparent diffusion coefficient (ADC) dec
rease should be associated with the severity of the perfusion deficit in is
chemic tissue of acute stroke patients. Perfusion- and diffusion-weighted s
cans were performed in 11 patients with sudden onset of neurologic deficits
: within the last 6 hours and T2-weighted magnetic resonance imaging scans
were obtained after 6 days. Parameter images of the maximum of the contrast
agent concentration, time to peak. relative cerebral blood volume, relativ
e cerebral blood flow, and relative mean transit time were computed from th
e perfusion-weighted data. A threshold function was used to identify tissue
volumes with stepwise ADC decreases. An onionlike distribution of successi
vely decreasing ADC values was found, with the lowest ADC in the center of
the ischemic region. Correspondingly, tissue perfusion decreased progressiv
ely from the periphery toward the ischemic core. This effect was most prono
unced in the time-to-peak maps, with a linear association between ADC decre
ase and time-to-peak increase. Apparent diffusion coefficient values decrea
sed from the periphery toward the ischemic core, and this distribution of A
DC values was strongly associated with the severity of the perfusion defici
t.