脑血管储备是脑血管狭窄时脑组织的主要代偿机制，当其达到最大值不能继续上升时会导致脑梗死和认知功能障碍。目前主要通过血管激发试验时进行脑灌注检查来评价脑血管储备。然而脑灌注检查只能得到脑血流量的变化，不能得到脑氧代谢情况，所以其不能全面反映脑血管储备。我们前期研究发现，脑氧摄取分数和大脑氧代谢率可以更好的反映脑血管狭窄时的脑组织氧摄取量和缺氧程度。据此，我们认为脑氧摄取分数和大脑氧代谢率能比脑灌注参数更好的评价脑血管储备。本研究拟用脑血管狭窄动物模型在血管激发前后分别进行多期CT血管成像和氧摄取分数、多相动脉自旋标记、血管编码动脉自旋标记成像等磁共振序列检查。用得到的脑血流量、脑氧摄取分数和大脑氧代谢率在血管激发前后的变化评价脑血管储备。并用多期CT血管图像与病理标本对照研究量化侧枝循环。本研究可更全面揭示脑血管储备变化规律，对脑缺血疾病的预防和治疗将有重要意义。

Cerebrovascular reserve (CVR) is the major compensatory mechanism during hypoperfusion. Cerebral infarction and cognitive dysfunction often occur to patients with cerebral vascular stenosis. It includes the brain structure reserve (collateral circulation), the cerebral blood flow reserve, the brain function reserve (oxygen metabolism reserve) and the brain metabolism reserve. At present, CVR is evaluated by comparing perfusion parameters between the basic state and the excited state through CT perfusion. Perfusion parameters only can reflect the cerebral blood flow (CBF) but cannot reflect oxygen metabolism. And they can directly reflect the oxygen uptake of brain tissue. Therefore, we believe that OEF and cerebral oxygen metabolism rate can evaluate CVR better than cerebral perfusion parameters. In this study, the animal model of cerebral vascular stenosis was established and examined with CT perfusion and MRI, including multiphase pseudocontinuous arterial spin labeling, oxygen extraction fraction (OEF), vessel-encoded arterial spin labeling imaging. Cerebral metabolic rate of oxygen can be got by using OEF and cerebral brain flow. We study CVR by using cerebral blood flow, OEF and brain oxygen metabolism rate. Comparing collateral circulation displayed by multi-period CTA and the number of vascular displayed by immunohistochemical brain tissue, we determine whether it can accurately quantify collateral circulation. This study can more comprehensively reveal the change of CVR, and it is very important for the prevention and treatment of cerebral ischemia.