CO_2吸入负荷MR灌注成像对大脑中动脉重度狭窄或闭塞脑血管储备功能的初步研究

MR Perfusion-weighted Imaging with CO_2 Inhalation Stress Test in Assessment of Cerebrovascular Reserve in Severe Middle Cerebral Artery Stenosis or Occlusion

目的脑动脉狭窄或闭塞引起局部脑血流动力学和脑血管储备(CVR)功能改变,是缺血性脑卒中的重要危险因素。本研究应用CO_2吸入负荷MR灌注成像对大脑中动脉重度狭窄或闭塞患者CVR功能进行评估。资料与方法选择28例一侧大脑中动脉重度狭窄或闭塞患者和对照组10例正常人,在CO_2吸入负荷试验前后2次进行MR灌注扫描,选取大脑中动脉重度狭窄或闭塞患侧大脑中动脉供血区、健侧对应部位及对照组大脑中动脉供血对应区作为感兴趣区(ROI),测量相对脑血容量(r CBV)、相对平均通过时间(r MTT)、相对脑血流量(r CBF)及CVR功能。结果 1大脑中动脉重度狭窄或闭塞患侧ROI的r CBV、r CBF、r MTT CO_2吸入负荷试验前分别为149.16±33.01、18.04±5.24、8.65±1.81,CO_2吸入负荷试验后分别为156.23±21.60、23.77±8.77、8.72±3.01,CO_2吸入负荷试验后r CBV、r CBF及r MTT增加(t=1.238、2.561、2.647,P<0.05);大脑中动脉重度狭窄或闭塞健侧ROI的r CBV、r CBF、r MTT CO_2吸入负荷试验前分别为176.22±40.12、22.43±5.74、8.10±3.71,CO_2吸入负荷试验后分别为198.54±39.87、27.64±7.22、8.03±2.97,CO_2吸入负荷试验后r CBV、r CBF增加(t=1.780、1.665,P<0.05)、r MTT减少(t=2.871,P<0.05)。2大脑中动脉重度狭窄或闭塞患侧、健侧及对照组ROI的CVR分别为18.9%、26.8%、39.1%,患侧与对照组、健侧与对照组、患侧与健侧组间CVR比较,差异均有统计学意义(t=1.604、2.321、1.874,P<0.05)。结论 CO_2吸入负荷试验MR灌注成像是评估大脑中动脉重度狭窄或闭塞患者脑血流储备能力的有效方法,具有重要价值。

Purpose Alteration of the regional cerebral flow and cerebrovascular reserve（CVR） caused by cerebral artery stenosis or occlusion is an essential risk factor for ischemic stroke. This study aims to assess the CVR in patients with severe middle cerebral artery（MCA） stenosis or occlusion by using MR perfusion-weighted imaging（PWI） with CO2 inhalation stress test. Materials and Methods PWI were performed before and after CO2 inhalation stress on 28 patients with severe middle cerebral artery stenosis or occlusion and 10 healthy volunteers. The regions of interest（ROI） were put on the affected hemisphere of the MCA blood supply area and the contralateral side in both groups. The relative cerebral blood volume（r CBV）, relative mean transit time（r MTT）, relative cerebral blood flow（r CBF） and CVR were measured. Results 1 The r CBV, r CBF and r MTT of the affected side were 149.16±33.01, 18.04±5.24, 8.65±1.81 before CO2 inhalation stress, and 156.23±21.60, 23.77±8.77, 8.72±3.01 after CO2 inhalation stress. The r CBV, r CBF and r MTT were significantly increased（t=1.238, 2.561 and 2.647, P〈0.05） after CO2 inhalation stress. The r CBV, r CBF and r MTT of the contralateral side were 176.22±40.12, 22.43±5.74, 8.10±3.71 before CO2 inhalation stress, and 198.54±39.87, 27.64±7.22, 8.03±2.97 after CO2 inhalation. The r CBV, r CBF was significantly increased（t=1.780 and 1.665, P〈0.05） while r MTT was significantly decreased（t=2.871, P〈0.05） after CO2 inhalation. 2 The CVR of the affected side, contralateral side and control group were 18.9%, 26.8%, and 39.1%, respectively. There were significantly differences（t=1.604, 2.321 and 1.874, P〈0.05） between the affected and contralateral side, the affected side and control group, the contralateral side and control group. Conclusion PWI with CO2 inhalation stress test is valuable in assessing the cerebrovascular reserve in patients with severe middle cerebral artery stenosis or occlusion.