RESUMO
Objectives To evaluate the performances of transcranial Doppler (TCD) and vessel-encoded arterial spin labeling MRI perfusion imaging (VE-ASL) in the evaluation of collateral circulation of cerebral arteries. Methods Thirty patients with unilateral ICA or MCA stenosis diagnosed by TCD and carotid duplex ultrasound and confirmed by MRA underwent VE-ASL. Peak systolic velocity (PSV) of bilateral MCA in the same depth, distal to the stenosis site, was recorded. Cerebral blood flow (CBF) in bilateral MCA territories was measured by VE-ASL. The detection rates of collater-al flow using TCD and VE-ASL were compared. Results TCD revealed that PSV in the ipsilateral and contralateral MCA were (31.6 ± 10.5) cm/s and (83.1 ± 9.2) cm/s, respectively. VE_ASL revealed that CBF in the ipsilateral and contralateral MCA territory were (22.5±9.8) mL·min-1·100g-1 and (31.7±8.3) mL·min-1·100g-1, respectively. The PSV ratio of the ipsi-lateral/contralateral MCA was significantly lower than the CBF ratio of the ipsilateral/contralateral MCA(0.37 ± 0.173 vs. 0.66±0.141, P=0.001). The detection rates of collateral flow using TCD were lower than those using VE-ASL. The detec-tion rate was 26.7% vs. 70% on TCD vs. VE-ASL in anterior collateral circulation (P=0.001), was 16.7% vs. 60% (P<0.001) on TCD vs. VE-ASL in posterior collateral circulation. The total display rate of collateral flow was 36.7%vs. 86.7%on TCD vs. VE-ASL (P<0.001). Conclusions TCD is inferior to VE-ASL in evaluating the collateral circulation because of the limitations including the anatomical variations of the circle of Willis and formation of leptomenigeal anastomoses.