一站式CT灌注成像评估单侧颈内动脉重度狭窄或闭塞患者颅内血流动力学改变及Willis环侧支循环情况

摘要

目的：通过对单侧颈内动脉重度狭窄或闭塞患者行脑CT灌注成像联合CTA一站式扫描，对其脑血流动力学改变及 Willis环侧支循环代偿作用进行评价，为临床血管再通治疗提供血流动力学依据。方法：对40例经颈部血管超声或头颈CTA检查确定为单侧颈内动脉重度狭窄或闭塞患者（狭窄率＞70％）行320排 CTPI 检查，重建灌注参数图及4D-CTA图。在基底节层面选取大脑前动脉供血区、大脑中动脉供血区及前、后分水岭区作为感兴趣区行灌注参数测量，包括脑血容量（CBV）、脑血流量（CBF）、平均通过时间（MTT）和达峰时间（TTP），对患侧与健侧的各项灌注参数进行对比分析。根据CTA图将 Willis环分为开放组及未开放组，对两组的dTTP（患侧TTP-健侧TTP）、dMTT、rCBF（患侧CBF／健侧CBF）及rCBV进行比较，采用χ2检验对比分析两组间各个兴趣区的缺血程度（rCBF＜80％为重度，＞80％为轻度），评价 Willis的代偿能力。结果：与健侧比较，患侧脑区 MTT、TTP 延长，CBV 增大，CBF 略下降，其中在大脑中动脉供血区和前、后分水岭区CBV、MTT、TTP差异有统计学意义（P＜0．05），大脑前动脉供血区 MTT、TTP 差异有统计学意义（P＜0．05）。Willis环未开放组各兴趣区 dTTP、dMTT、rCBV 和 rCBF 均高于开放组。仅前分水岭区的脑缺血程度与Willis环是否开放有相关关系（P＝0．001）。结论：单侧颈内动脉重度狭窄及闭塞患者的患侧脑组织 MTT、TTP 延长，部分脑区CBF下降，处于低灌注状态；Willis环对患侧有一定的代偿作用，在前分水岭区代偿作用明显；CTPI可以为颈内动脉重度狭窄或闭塞患者提供血管再通依据。%Objective:To evaluate the hemodynamic change and collateral compensatory effect of Willis circle by ap-plying brain CT perfusion combined with CT angiography in patients with severe stenosis or occlusion of unilateral internal carotid artery,this is to provide hemodynamic basis for vascular recanalization treatment.Methods:40 patients underwent whole brain 320-slice dynamic volume CT scan,and perfusion parameters maps and 4D-CTA images were calculated.Perfu-sion parameters were recorded and compared,including cerebral blood volume (CBV),cerebral blood flow (CBF),mean transit time (MTT)and time of peak time (TTP).In the basal ganglia level,anterior cerebral artery,middle cerebral artery, anterior and posterior watershed area were selected as areas of interest.Paired t test was used to analyze the means of the affected brain tissue and the contralateral corresponding parts of the brain tissue.According to the CTA images,Willis's cir-cle was divided into open group and closed group.In this two groups,dTTP (TTP with affected side-the contralateral side), dMTT (MTT with affected side-the contralateral side),rCBF (CBF on affected side/contralateral CBF)and rCBV (CBV on affected side/contralateral CBV)were compared.Ischemic level of the two groups were measured and compared by usingχ2-test,in order to evaluate compensatory ability of Willis's circle.Results:Compared with the control group,MTT and TTP delayed,CBV increased,CBF slightly decreased.Compared with the control group,in middle cerebral artery,anterior and an-terior watershed areas,CBV,MTT and TTP showed significant difference (P<0.05);In anterior cerebral artery area, MTT,TTP showed significant difference (P<0.05).Compared with Willis circle open group and closed group,dTTP and dMTT increased,rCBV and rCBF slightly lowered.Only in anterior watershed area,there was statistically significant diffe-rence in the ischemic level between the two groups.Conclusion:Ipsilateral brain tissue of patients with severe stenosis or oc-clusion of unilateral internal carotid artery had prolonged MTT and TTP,decreased CBF as well as hypo-perfusion state;Willis circle has certain compensatory effect on the affected side,especially in the anterior watershed area.CTP can provide basis of vascular recanalization for patients with severe stenosis or occlusion of unilateral internal carotid artery.