减压后脑肿大早期磁共振弥散加权像和病理的实验研究

Experimental study of diffusion-weighted MRI and pathology in the early stage of postdecompressive brain bulk enlargement

目的 :探讨减压后脑肿大早期病理基础。方法 :利用磁共振弥散加权成像 (DWI)对脑水肿检测的敏感性和特异性 ,于减压后 2h、4和 6h三个时点 ,对 1 8只猫作减压后脑肿大动态DWI检查 ,每相应时点处死 6只猫形成一组 ,制取脑标本作Evan′sBlue染色、光镜和电镜检查。结果 :减压后 2hDWI即显示脑肿大部位为低强度信号区 ,其范围在减压后 4和 6h明显扩大 ,中线向对侧移位加剧 ;1只猫减压后 6h肿大部位原低强度信号区转变为高强度信号区。减压后 2h即见脑肿大部位Evan′sBlue染色 ,减压后 4和 6h染色范围明显扩大。减压后 2h光镜和电镜检查发现全脑微小血管内淤血 ,但以脑肿大部位为重并伴有微小血管周围间隙明显扩大 ;减压后 6h肿大脑组织内变性坏死脑细胞增多。结论 :减压后脑肿大早期 (<2h)由充血性脑肿胀和血管源性脑水肿共同构成 。

Objective:To explore the pathological basis in the early stage of postdecompressive brain bulk enlargement Metholds:Using the sensitivity and specificity of diffusion weighted MRI(DWI) to detect brain edema, the dynamic DWI was performed in 18 cats of postedecompressive brain bulk enlargement at three time points (2, 4 and 6 hours) after decompression 18 cats were randomly assigned into three groups (2h group, 4h group and 6h group) Every group was consisted of six cats killed at each corresponding time point after decompression, then made brain specimens to be observed with Evan's Blue staining,light and electronic microscope Resutls:2 hours after decompression, DWI shown the area of brain bulk enlargement was hypointensity signal 4 or 6 hours after decompression, it expanded and the midline of brain shifted more obviously to the contralater side Only one cat, it returned into hyperintensity signal by 6 hours after decompression Evan's Blue staining area in swollen brain extravasated more obviously within 4 or 6 hours than within 2 hours Under light and electronic microscope, congestive dilation of micro and small cerebral vessels in double hemisphere was found within 2 hours after decompression, but it was more obvious and accompanied with expand of the space around cerebral vessels in swollen brain Degeneratio and Necrosis of cerebral cell multiplied in swollen brain by 6 hours after decompression Conclusion: In the early stage (<2 hours) of postdecompressive brain bulk enlargement, the swollen brain was consisted of congestive dilation of cerebral vessels and vasogenic brain edema The cytotoxic brain edema would be appeared at about 6 hours following decompression