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[Effects of acute cerebral ischemia on cerebral perfusion: quantitative evaluation by contrast-enhanced ultrasound in dogs].

OBJECTIVE
To evaluate the changes of cerebral blood flow (CBF) with real-time contrast-enhanced ultrasound (CEU) in a canine model of acute cerebral ischemia.


METHODS
Cerebral perfusion was assessed in 6 dogs subjected to craniotomy with CEU at the time of 0, 30, 60, 90 and 120 min after occlusion of the left common carotid artery (LCCA). The microvascular volume (A) and blood flow velocity (beta) in the brain were measured from the time-versus-acoustic intensity plots, and the value of Axbeta were calculated. 99mTc-ECD brain single photon emission computed tomography (SPECT) was performed on the day before the experiment and at 120 min after LCCA occlusion. The radioactive counts on both sides of the cerebral cortex were calculated.


RESULTS
A significant correlation was found between Axbeta from CEU and volume of the blood flow of the CCA from Doppler flowmetry. A, beta and Axbeta values varied significantly between the different time points (P>0.001). The ipsilateral hemisphere showed a low-perfusion state while the contralateral hemisphere showed a high-perfusion state immediately after the occlusion.


CONCLUSIONS
The changes of beta is the main regulation mechanism during acute cerebral ischemia in dogs.