急性脑静脉闭塞脑损伤治疗时间窗初探:DWI与病理学对照实验研究

目的:探讨急性脑静脉闭塞模型脑实质损伤治疗时间窗的存在及其意义.方法:选择新西兰大白兔28只随机分为2组(实验组24只,对照组4只),实验组动物经一侧颈内静脉注入醋酸纤维素聚合物(CAP),分别于术后1、3、6、12、24和48 h行T1WI、T2WI和扩散加权成像(DWI)检查.各时间点MR扫描后取兔脑组织做胶质纤维酸性蛋白(GFAP)表达的免疫组化研究及电镜观察.结果:DWI、T2WI、GFAP的表达和电镜检查均能显示急性脑静脉闭塞模型脑实质损伤及其变化.DWI在术后1 h即能显示脑实质病变(ADC值下降),术后3 h DWI和T2WI均能显示病变;术后6 h前,DWI上有扩散异常的脑组织容积明显大于T2WI上异常高信号区的容积(t=13.69,P＜0.01);术后12、24和48 h病变区ADC值逐渐回升,T2WI上病变容积与DWI上的扩散异常区的容积比较,差异无显著性意义(t值分别为1.467、0.996和2.017,P＞0.05).术后1 h病变区GFAP阳性细胞增多,染色加深,胞体增大,突起增粗增长,术后3～6 h变化更明显,病理学改变以血管源性水肿为主,12 h后出现脑组织大量坏死.对照组未见上述各种异常表现.结论:DWI可准确评价急性脑静脉闭塞模型脑实质损伤程度,结合GFAP的表达,在探讨急性脑静脉闭塞脑损伤的治疗时间窗的存在及其意义中具有重要价值,在其发生发展过程中确实存在潜在的治疗时间窗.

Preliminary Experimental Study of the Therapeutic Time-window in Brain Parenchymal Lesion of Acute Cerebral Venous Occlusion:Correlation of Diffusion Weighted Imaging and Histopathology

Objective:To discuss the existence and significance of therapeutic time-window in brain parenchymal lesions of acute cerebral venous occlusion in animal models. Methods:28 New Zealand white rabbits were randomly divided into 2 groups,including experiment group (n=24) and control group (n=4).After injection of cellulose acetate polymer (CAP) into left or right internal jugular vein,T2WI and DWI were performed and glial fibrillary acidic protein (GFAP) expression and electronscopy examination of brain tissue were analyzed,at an interval of 1,3,6,12,24 and 48h.Results:The process of occurrence and development of brain parenchymal lesions induced by acute cerebral venous occlusion could be showed by DWI,T2WI,GFAP expression and electronmicroscope examination.Decrease of apparent diffusion coefficient (ADC) values within brain lesion could be showed on DWI within 1h of operation.After 3h,lesion could be assessed on DWI as well as T2WI.The volume of DWI abnormality was bigger than that of T2WI before 6h (t=13.69,P<0.01).No obvious difference of the volume on T2WI abnormality and DWI was found after 12,24,and 48h (t=1.467,0.996,2.017 respectively;P>0.05),and the ADC values of the brain parenchymal lesions subsequently increased gradully.At 1h after operation,the number of GFAP positive cells increased,deeply stained and enlarged,the neurodendrites elongated and thickened.These changes became more obvious after 3h and 6h.Vasogenic edema was the main patho-histology findings within brain lesion,large amount of necrosis was found after 12h.The above-mentioned abnormalities were not assessed in the control group.Conclusion:The severity of brain parenchyma injury after acute cerebral venous occlusion could be accurately evaluated by DWI,DWI in combination with GFAP expression is helpful in the demonstration of the existence and significance of therapeutic time-window in brain lesion after acute cerebral venous occlusion.