基于多b值的体素内不相关运动（IVIM）核磁成像技术可以同时获得弥散和灌注两方面参数，但在急性脑梗死超早期的缺血脑组织评估中，尚未得到验证，同时多b值的数量与数值也存在争议。前期研究发现，基于IVIM的f及f˙D*图与传统灌注MR有较好的相关性，可以准确反映脑缺血状态，需进一步验证其与脑缺血组织的相关性。据此提出假设：确定IVIM相关参数的缺血阈值及优化b值，可替代传统灌注影像，用于区分梗死核心、缺血半暗带和良性缺血组织。本项目拟建立急性脑梗死的恒河猴动物模型，采集不同时相点的多模态影像数据，通过观察IVIM成像与传统灌注影像之间的相关性，建立IVIM灌注参数的缺血阈值并优化多b值；收集急性脑梗死患者超早期的多模态MR数据，通过与最终梗死体积比较，对IVIM灌注阈值进行验证和修正。有望建立一个基于IVIM成像技术，能准确区分急性脑梗死缺血脑组织的影像学标志物，用于指导急性脑梗死的治疗决策。

Intravoxel Incoherent Motion MR imaging based on multiple b values has both the information of perfusion and diffusion. But there are still uncertainties about if the technique can be used in assessing cerebral ischemic tissue at hyper-acute phase of cerebral infarction and controversies about the numbers and values of multiple b values. In previous study, we demonstrated that f and f˙D* from IVIM imaging have good correlations with traditional perfusion MR and also can distinguish the ischemic tissue from normal cerebral tissue, which suggested our hypothesis that IVIM imaging can be a possible surrogate to differentiate the benign oligemia, penumbra and infarct core. We will build rhesus monkey acute ischemic stroke model with multi-modal MR imaging. IVIM perfusion parameters and traditional perfusion MR will be compared to verify our hypothesis and the IVIM threshold for ischemic tissue will be built. We will collect the multi-modal MR imaging from patients with hyper-acute cerebral infarction to verify the threshold. The purpose of our study is to build an imaging biomarker based on IVIM, which can distinguish infarct core, penumbra and benign oligemia from each other to make right treatment decision.