CT灌注成像对脑缺血超急性期血管通透性连续观察的实验研究

Serial Changes of Microvascular Permeability within 6h of Experimental Acute Cerebral Ischemia Using Perfusion CT Imaging

目的：通过CT灌注技术PS参数变化连续观察脑缺血6h内微血管通透性变化。方法：将55只兔随机分为对照组（5只）和实验组（50只），实验组颈内动脉注射自体血栓，对照组注射生理盐水。所有动物行0．5、1、2、3、4、5和6h多层螺旋CT灌注成像（CTP）并获得表面通透性（PS）图，测量并比较不同时间点梗死区和镜像区PS值。结果：对照组兔脑无异常。实验组41只（82％）动物模型制作成功。均在CTP图像上显示局部异常灌注，病理学上可见不同程度神经元肿胀及破坏、组织水肿、血管周围间隙扩大、及淋巴细胞浸润等。缺血局部脑组织Evans蓝染。PS图上缺血区为宽片状或斑点状通透性增大，伪彩图为红色或接近红色彩阶。PS值变化以0．5h为著，1～6h缺血区PS值波动不明显。各时间点缺血区的微血管通透性明显大于镜像区（t值在2．617～10．612，P值均〈0．005）。结论：多层螺旋CT灌注成像能有效显示脑缺血超急性期微血管通透性的变化，脑缺血超急性期缺血局部PS较镜像区明显增大。

Objective： To study and evaluate serial changes of microvascular permeability within 6h after acute cerebral ischemia of rabbits using permeability surface imaging of CT perfusion （CTP）. Methods： Fifty-five rabbits were randomly divided into control group （n= 5） and experimental group （n= 50）. We injected autologus ernboli into unilateral carotid arteries of experimental animals. Only 5ml normal saline was infused into carotid arteries of control rabbits. CTP was done for all animals from 0. 5,1,2,3,4,5 to 6h. We measured the PS values of infarcted areas and symmetrical areas of contralateral hemisphere. Results：There were no abnormal manifestation found to all control rabbits. Abnormal perfusion of the brain was found in forty-one experimental rabbits （41/50,82% ）. Swelled and destructed neurons, edema, enlarged peri vascular space, and infiltration of lymphocyte were detected pathologically. Evans blue（EB） stainning of infarcted hemisphere was found. On PS images,we detected speckled or patchy regions with red colour, which represented the increase of microvascular permeability. After the peak value at 0.5h,the PS value of infarcted areas decreased quickly to a steady level. The value of PS of infarction at every time point was much higher than that of contralateral areas （t= 2. 617 - 10. 612,P=0. 000-0. 027）. Conclusion： The changes of microvascular permeability of superacute cerebral ischemia can be evaluated with multislice CT perfusion. The PS value of superacute infarction increases tremendously.