重度颈动脉狭窄患者颈动脉粥样硬化斑块的稳定性对脑灌注的影响

目的 对比研究重度颈动脉狭窄患者稳定与易损动脉粥样硬化斑块间的脑灌注情况，探讨斑块性质与脑灌注的关系。方法 利用磁共振成像技术检测颈动脉动脉粥样硬化性病变，并筛选单侧颈内动脉狭窄程度为70％～99％患者30例。对30例患者行动态磁敏感对比增强磁共振成像,测定患侧与健侧大脑半球、额叶、顶叶、半卵圆中心、皮质分水岭前区、皮质分水岭后区的平均通过时间（MTT）、相对脑血流量（rCBF）、相对脑血容量（rCBV）比值。将颈动脉粥样硬化斑块的纤维帽是否完整、斑块表面是否有大片钙化、其内是否有近期出血及是否有较大的脂质中心作为易损斑块诊断标准，分为稳定和易损斑块两组，比较两组患者脑血流动力学参数的差异。结果 与稳定斑块组比较，易损斑块组在皮质分水岭前区和后区的MTT值明显延长(t =1.561，P =0.042和t =1.227，P =0.038)，rCBF和rCBV无统计学差异。上述两组在其余部位的血液动力学参数比值无统计学差异。结论 颈动脉粥样硬化斑块的稳定性和相应皮质分水岭供血区域灌注情况有关，易损斑块容易导致同侧皮质分水岭区低灌注，MTT是最敏感的指标。

Effect of Carotid Atherosclerotic Plaque on Cerebral Perfusion in Patients with Severe Carotid Artery Stenosis

Objective To compare the cerebral perfusion of the stable and vulnerable carotid atheroscleroticplaque for the patients with internal carotid artery(ICA) stenosis ranging from 70% to 99%.Methods Total 30 patients with unilateral carotid artery stenosis ranging form 70% to 99% wereselected to be scanned with perfusion weighted imaging(PWI). On the mean transition time(MTT),regional cerebral blood flow(rCBF) and regional cerebral blood volume(rCBV) map, the region ofinterest (ROI) was placed on the brain hemisphere, frontal lobe, parietal lobe, centrum semiovale,anterior cortical watershed and posterior cortical watershed. The MTT, rCBF and rCBV ratio of thepatients were calculated as stenotic side against contralateral side. Based on the status of the fibrouscap, with/without hemorrhage, superficial calcification, large lipid core, we divided the carotidplaque into two groups: stable and unstable plaque. The cerebral PWI of these two groups wereevaluated.Results The MTT ratios of the anterior cortical watershed and posterior cortical watershed wereprolonged significantly in unstable group compared with stable group(t =1.561, P =0.042 and t =1.227,P =0.038), but the rCBF, rCBV were not changed obviously. There were no significantly difference inthe MTT, rCBF and rCBV ratio of the brain hemisphere, frontal lobe, parietal lobe, centrum semiovalebetween the stable and unstable group.Conclusion The stability of the carotid atherosclerotic plaque has close relationship with theperfusion of relative cortical watershed region, and MTT is the most sensitive parameter to detectthe unilateral hypoperfusion.