基于灌注和通透性MR成像的急性脑梗死出血转化风险的预测研究

Hemorrhagic Transformation(HT) has impacts on the prognosis of acute ischemic stroke during its early stage. Blood brain barrier(BBB) disruption plays a central role in HT. So that Permeability imaging, which can provide the information about absolute BBB permeability(aBBBP), has attracted increasing attentions. However, based on our former study, we raised an idea that is: Brain tissues, which having lowest perfusion level, will have the most severe BBB disruption, but permeability imaging can't detect it accurately. The relative BBBP(rBBBP), which contains the information of Perfusion and Permeability, may be a better choice to predict the risk of HT. In our study, we plan to combine perfusion MR with permeability MR to evaluate cerebral blood flow(CBF) and aBBBP in ischemic area of animal model. We try to find the correlation among CBF, aBBBP and HT with different recanalization, then to assess these correlations by neuropathological examination to prove our hypothesis. Then, we will include acute cerebral infarct patients to observe the possibilities of HT in different perfusion, different permeability, and different recanalization. Based on the correlation among CBF, aBBBP and HT, we will build a mathematical model of rBBBP which contains the information of CBF and aBBBP and may predict the Risk of HT better than ever. This rBBBP mathematical model may be another imaging marker in initail evaluation of acute cerebral infarction.

急性脑梗死早期的出血转化(HT)与预后密切相关。血脑屏障(BBB)破坏是继发HT的关键步骤，准确评估BBB状态具有重大的意义。通透性MR所得到的BBBP绝对值(aBBBP)能够反映BBB受损的严重程度,近年来被用于HT的预测，但准确性尚存争议。本项目在已有的工作基础上，提出"通透性成像不能准确评估严重低灌注脑组织的BBB破坏程度"的假设，指出"结合灌注与通透性成像得到的BBBP相对值(rBBBP)才能准确预测出血转化"。研究将建立急性脑梗死大鼠模型，评估缺血区脑血流量(CBF)和aBBBP的变化，通过病理学验证影像学改变与HT的相关程度，验证先期假设。之后筛选临床病例，利用MR观察不同灌注条件下缺血脑组织发生HT的可能性，以及HT与aBBBP之间的关系；尝试建立一个基于aBBBP/CBF，能够准确预测HT风险的rBBBP数学模型，使之成为急性脑梗死治疗决策与预后评估中新的影像学标志物。

急性脑梗死早期的出血转化(HT)与预后密切相关。血脑屏障(BBB)破坏是继发HT的关键步骤，准确评估BBB状态具有重大的意义。本项目在已有的工作基础 上，提出"通透性成像不能准确评估严重低灌注脑组织的BBB破坏程度"的假设，指出"结合灌注与通透性成像得到的BBBP相对值(rBBBP)才能准确预测出血转化"。首先筛选临床病例，通过PCT首过模型数据，得到急性脑梗死的通透性参数，并与出血转化的发生相比较后发现：1) HT区域的BBBP值相对较低而灌注值较高；2) 局部低BBBP和全脑高BBBP可以较好的预测HT。在此研究基础上还进行了侧支循环等研究，发现通透性参数中的Ktrans值可以较好的评估2-3级侧支循环。以上研究表现，通透性影像联合灌注影像，可以更好的了解急慢性脑卒中的病理生理状态，有望使之成为急性脑梗死治疗决策与预后评估中新的影像学标志物。