中文摘要：

目的采用5％CO2吸入CT灌注成像研究症状性大脑中动脉（MCA）缺血患者MCA分布区脑血管储备能力。资料与方法临床诊断为症状性MCA缺血且无心、肺疾病患者20例，基础态CT灌注成像TTP参数图显示有MCA供血区TTP延长。首先进行常规脑灌注CT检查（基础态）；20min后，面罩吸入5％CO2，持续吸入2min后再次行脑灌注CT检查（激发态）。感兴趣层面选择基底节层面和放射冠层面，层厚10mm。计算机后处理获得脑血流量（CBF）参数图后，于MCA分布区皮层多点手绘感兴趣区，分别计算双侧皮层CBF，计算双侧CBF变化率r=（CBF激发态-CBF基础态）／CBF基础态×100％；比较双侧激发后CBF改变，分析患侧MCA分布区脑血管储备能力。结果患侧MCA分布区皮层CBF明显低于健侧。健侧MCA分布区基础态和激发态CBF可见不同程度的改变：升高17例，降低3例。对17例激发后升高的患者进行分析，根据计算将患侧CO：激发反应分为：Ⅰ型，激发后CBF升高；Ⅱ型，激发后CBF变化不明显；Ⅲ型，激发后CBF降低。结论5％CO2吸入CT灌注成像激发试验可以评估脑血管储备能力，具有重要的临床价值。

英文摘要：

Objective To investigate the capacity of cerebrovascular reserve （CVR） by 5 % CO2- inhalation CT perfusion challenge test in symptomatic middle cerebral artery stenosis disease. Materials and Methods In 20 subjects the CVR was bilaterally assessed by measurement of cerebral blood flow （CBF） in response to inhalation of 5% CO2. These subjects had the deficit symptom in relation with middle cerebral artery （MCA） territory without the diseases of heart and lung. We selected the two axial slices （thickness, 10mm） traversing basal ganglia and coronal radiate respectively. 40 ml nonionic contrast agent was administered with a constant flow rate of 8 ml/s via the antecubital vein using a power injector. Dynamic CT was performed during a resting state and after inhalation of 5 % CO2 for two minutes consecutively in the same patients. The delay time between the two scan was 20 minutes. For each of the MCA territory section, an experienced neuroradiologist drew regions of interest （ROIs） on CBF map by hand and set over the cortical gray matter of the expected territory of the MCA bilaterally. The mean CBF values contained within each ROI were averaged. To compare the changes of the bilateral mean CBF values, the CVR of the bilateral MCA territory was calculated. The formula was r = （ CBF activation - CBF resting）/CBF resting × 100% . Results There was a remarkable significance between the mean CBF values of the bilateral MCA hemispheres, the CBF was decreased more significantly in middle cerebral artery （MCA） stenosis territory than that in contralateral side, different degree change of CBF was occurred in middle cerebral artery （MCA） non stenosis territory on activation and resting state, CBF increased in 17 cases, CBF decreased in 3 cases. The CVR values of the involved MCA territory were divided into three groups： diminished response, no response and steel blood. Conclusion 5%CO2- inhalation CT perfusion challenge test is an accessible method to evaluate the capacity of cerebrovascular