脑梗死SD大鼠模型死亡后脑部MRI表现

摘要

Purpose To perform MRI examination after the death of SD rat model due to cerebral infarction and to investigate the changing characteristics of cerebral infarction during postmortem examination. Materials and Methods Middle cerebral artery occlusion (MCAO) model was established on 21 SD rats by applying modified suture method. 13 to 56 h after modeling, 12 dead SD rats were collected for the experiment. The bodies were stored at an environment with a temperature of 10-15°C and relative humidity of 45%-55%. Head MRI was performed 12 h after modeling and at 8, 24, 48, 72 and 96 h after death respectively, and apparent diffusion coefficient (ADC) values of infarction and contralateral brain tissue were calculated. At each post-mortem time point, ADC values of bilateral cerebral hemispheres, ADC values of infarction and living infarction, and ADC values of non-infarcted brain and living non-infarcted zone were compared. Brain tissue was taken after scan for pathological diagnosis and compared with diagnostic results of postmortem MRI (pmMRI). Results The right cerebral signal of rats was abnormal 12 h after cerebral infarction and after death. Eight rats were found to have shifted cerebral middle-line structure to the left. ADC values of infarction at each time point after death were lower than that of non-infarction, the difference of which was statistically significant (P<0.05); ADC values of infarction were lower than that of living infarction, the difference of which was statistically significant (P<0.05); ADC value of non-infarcted area at each time point was lower than that of living non-infarcted area, the difference of which was statistically significant (P<0.05). Necrosis and disintegration of neurons, disintegration and liquefaction of glial fibers, infiltration of inflammatory cells and leakage of red blood cells were spotted in necrotic areas after receiving cerebral HE staining in rat. HE staining was consistent with the infarction zone indicated by pmMRI. Conclusion pmMRI can be used for the diagnosis of cerebral infarction via virtual necropsy.%目的 对脑梗死 SD 大鼠模型死亡后进行脑部 MRI 检查,探讨脑梗死在尸检过程中的影像学变化特征.材料与方法采用改良线栓法对21只SD大鼠制作右侧大脑中动脉闭塞(MCAO)模型.建模13~56 h后,收集12只死亡SD大鼠纳入本实验.尸体存放于10~15℃、相对湿度45%~55%.分别于建模后12 h以及死亡后8、24、48、72、96 h行头部MRI,计算梗死灶及对侧脑组织表观扩散系数(ADC)值.分别比较死亡后各时间点双侧大脑半球ADC值、梗死灶与活体脑梗死灶ADC值、非梗死区脑与活体非梗死区ADC值.扫描后取脑组织进行病理诊断,并与尸体磁共振成像诊断结果进行比较.结果 脑梗死12 h及死亡后大鼠右侧大脑信号异常,8只鼠大脑中线结构左移.死亡后各时间点梗死灶ADC值均低于非梗死灶,差异有统计学意义(P<0.05);梗死灶ADC值低于活体梗死灶,差异有统计学意义(P<0.05);死亡后各时间点非梗死区ADC值低于活体非梗死区,差异均有统计学意义(P<0.05).大鼠脑HE染色见坏死区域神经元坏死、崩解,胶质纤维崩解、液化,炎症细胞浸润及红细胞漏出.HE染色与尸体磁共振成像所示梗死区一致.结论 脑梗死急性期死亡后96 h内虚拟尸检有重要价值.