急性脑静脉闭塞磁共振灌注成像的实验研究

Experimental study on MR perfusion weighted imaging in acute cerebral venous occlusion

目的:用磁共振灌注加权成像(PWI)对急性脑静脉闭塞模型进行评价,观察脑实质损害的变化规律。材料和方法:家猫24只,随机分为手术组18只,假手术组6只。手术组采用开颅上矢状窦穿刺注射醋酸纤维素聚合物(CAP)制备急性脑静脉闭塞动物模型,假手术组仅行开颅上矢状窦暴露。术后1、3、6、12、24、48h用PWI对各组模型脑实质损害进行连续动态观察,并与病理学对照。结果:手术组15只猫脑实质内出现23个异常灌注区,表现为平均通过时间(MTE)延长,局部脑血容量(rCBV)增加、正常或降低。病变中心区和边缘区的相对平均通过时间比率(rMTE)1、3、6h稍延长,12h后明显延长。6h后病变中心区相对脑血容量比率(rrCBV)降低明显,12h后病变边缘区rrCBV逐渐降低,24h降低明显。6h病变中心区和边缘区rrCBV差异有统计学意义(t=-4.91,P<0.05),病理学检查见病变以血管源性水肿为主,12h出现坏死,可伴有出血性脑梗塞。假手术组未见上述各种异常表现。结论:PWI对急性脑静脉闭塞脑实质损害的动态变化、发病机理的判断具有重要价值。

Objective： To evaluate a model of acute cerebral venous occlusion with MR perfusion weighted imaging（PWI）, and to observe the changes of the brain parenchymal lesions. Materials and Methods： Twenty-four cats were randomly divid- ed into 2 groups, including operation group（n=18） and sham operation group（n=6）. Craniotomy was performed and the cellulose acetate polymer （CAP） solution was injected into the superior sagittal sinus to prepare a model of acute cerebral venous occlusion in operation group. PWI was continually performed at an interval of 1, 3, 6, 12, 24 and 48h after operation for each group to observe the brain parenchymal lesions, the pathologic changes were compared with MRI data. Results： In operation group, twenty-three abnormal perfusion regions were detected on PWI in 15 cats, appearing as prolonged mean time to enhance （MTE） increased, normal or decreased regional cerebral blood volume （rCBV）. Relative MTE （rMTE） of the central and marginal region prolonged slightly in 1, 3, 6h and prolonged obviously in 12h. Relative rCBV （rrCBV） in the central region of lesions decreased obviously in 6h, while rrCBV of marginal region decreased gradually in 12h and obviously in 24h. rrCBV of the central region showed significant difference （t=-4.91, P〈0.05） compared with marginal region in 6h. Pathologic examination mainly showed vasogenic edema in the lesions, followed by necrosis in 12h and sometimes with venous hemorrhagic infarction. No abnormal change was observed in sham operation group. Conclusion： PWI has great value in judging the dynamic changes and the pathogenesis of brain parenchymal lesions in acute cerebral venous occlusion.