CO_2混合氧刺激脑血流SPECT对单侧大脑中动脉狭窄患者脑血管储备力的评估

Evaluation of cerebrovascular reserve by CO_2 mixed oxygen stimulated SPECT cerebral blood flow tomography in patients with unilateral middle cerebral artery stenosis

目的：应用^99mTc—ECDSPECT脑血流灌注显像结合C02混合氧吸入前后脑血流量的改变来评价单侧大脑中动脉狭窄患者的脑血管储备力（CVR）。方法：血管造影确诊为单侧大脑中动脉狭窄70％～90％患者36例，所有患者均在脑血管造影检查后1～2周内分别进行1次静息^99mTc—ECD脑血流灌注断层显像和1次混合氧刺激脑血流灌注断层显像。计算机自动计算出大脑半球各部位12个区域，计算各部位感兴趣区（ROU放射性计数与小脑计数比值，≥85％为正常，〈85％为局部脑血流量（rCBF）减低；比较吸入CO2混合氧后各个ROI与静息状态下各ROI的rCBF计数与小脑比值的同一部位差值用来评价CVR。结果：各ROI吸入CO2混合氧刺激前后rCBF放射性计数与小脑比值测定出现下列4种结果：A型，静息状态下及CO2吸入负荷试验后各ROI放射性计数与小脑比值均未见明显异常者共8例（96个ROI，差值〉0）；B型，静息状态下比值未见异常，CO2吸入后rCBF计数与小脑比值减低的共9例（39个ROI，差值〈0）；C型，静息状态下rCBF计数减低，CO2吸入后rCBF与小脑比值更低、且计数减低范围扩大者10例（62个ROI，差值〈0）；D型，静息状态下rCBF计数减低，CO2吸入刺激后rCBF与小脑比值反而升高者9例（24个ROI，差值〉0）。结论：^99mTc—ECDSPECT脑血流灌注断层静息显像结合混合氧刺激负荷显像不仅可评价脑组织血流灌注障碍，而且可用于脑血管狭窄或闭塞后的CVR的监测，帮助临床早期识别卒中高危人群，从而早期采用相应治疗措施．预防卒中发生。

Objective To evaluate the cerebrovascular reserve （CVR） of patients with unilateral middle cerebral artery stenosis by ^99m-ECD SPECT imaging of cerebral blood flow perfusion combined with the change of cerebral blood flow after COz mixed oxide inhalation. Methods 36 patients with angiography confirmed 70% - 90% of unilateral middle cerebral artery stenosis received resting ^99m-ECD cerebral blood flow perfusion tomography and mixed oxygen stimulating brain perfusion SPECT imaging 1 - 2 weeks after cerebral angiography. The computer automatically calculated the 12 regions of brain hemisphere, and calculated the radioactivity counts and cerebellum ratio of region of interest （ROI） of each part; the result of I〉85% was marked as normal and that of 〈 85% indicated the reduction of regional cerebral blood flow （rCBF）. Comparison of rCBF count and cerebellum ratio of each ROI between resting-state and after CO2 mixed oxygen inhalation was administered to evaluate the CVR. Results There were 4 kinds of results of rCBF count and cerebellum ratio of each ROI in resting-state and after COz mixed oxygen inhalation： type A, the ROI radioactivity count and cerebellum ratio in resting state and after CO2 inhalation load test showed no obvious abnormalities in 8 patients （96 ROI, value 〉 0）; type B, those in resting state were normal, and rCBF count and cerebellum ratio were decreased after CO2 mixed oxygen inhalation in 9 patients （39 ROI, value 〈 0）; type C, rCBF count was decreased in resting state, and rCBF count and cerebellum ratio were further decreased after CO2 mixed oxygen inhalation in 10 cases （62 ROI, value 〈 0） ; type D, rCBF count was decreased in resting state, and rCBF count and cerebellum ratio were increased after CO2 mixed oxygen inhalation in 9 cases （24 ROI, value 〉 0）. Conclusions 99＂Tc-ECD SPECT brain perfusion imaging combined with CO2 mixed oxygen load imaging could not only evaluate the cerebral blood flow perfusion disorders but also can be used for monitoring the CVR after cerebral vascular stenosis or occlusion. And could help the clinical early identification of high-risk groups to the early stroke, and then to adopt corresponding treatment measures, and to prevent the occurrence of stroke.