新生猪缺氧缺血性脑损伤早期DWI影像学研究

DWI study in early stage of neonatal pig hypoxic-ischemic brain damage

关键词:  缺氧缺血性脑病  弥散加权成像  表观弥散系数

Key words:  hypoxic-ischemic encephalopathy  diffusion weighted imaging  apparent diffuse coefficient

摘要:

［目的］探讨新生猪急性缺氧缺血脑损伤（hypoxicschemic brain damage，HIBD）早期磁共振弥散加权成像（diffusion weighted image，DWI）图像及表观弥散系数（apparent diffuse coefficient，ADC）图的影像特点及ADC值的变化规律。［方法］选择生后3日龄约克猪随机分为对照组（假手术组）和实验组各8只，分别在缺氧缺血前及缺氧缺血后1 h、3 h、6 h、9 h和12 h进行MR扫描。DWI图像资料传送到GE AW4.4工作站，用functool软件后处理得到相应ADC图，选择病灶最明显层面测量ADC值。［结果］实验组在缺氧缺血后1 h，脑DWI图像上开始出现高信号区，ADC图呈点状低信号灶，在3 h和6 h的DWI图像上，高信号区范围明显扩大，主要分布于大脑皮层、侧脑室旁区及海马区，ADC图上出现与DWI图像上相对应的低信号区，随着时间的延长DWI图像上的高信号范围增大，12 h脑内呈弥漫性高信号改变，ADC图呈相应的弥漫性信号减低区。对照组在不同时间DWI及ADC图像上均未见异常信号改变。实验组ADC值1 h内下降明显，3 h最低，6 h以后开始回升，12 h接近正常。在1 h、3 h、6 h、9 h及12 h 实验组及对照组ADC值差异均有显著性意义（P<0.05）。［结论］DWI可以诊断早期缺氧缺血性脑水肿，ADC值从病理生理水平反映了早期缺血缺氧性脑水肿的变化规律。

Abstract:

［Objective］To study the imaging features and the time-variation of diffusion weighted imaging (DWI) and apparent diffuse coefficient (ADC) at early stage of hypoxic-ischemic brain damage (HIBD)of neonatal pigs.［Methods］The neonatal pigs were divided into 2 groups randomly:pseudo-operation group (n=8,as control group) and operation group (n=8).MRI was performed at a different time points of 0 h,1 h,3 h,6 h,9 h and 12 h after HIBD.DWI data were processed in GE AW4.4 to get ADC maps and ADC values.［Results］Significantly high signal intensity on DWI and low signal intensity on ADC maps were observed in 1 hour after HIBD operation,which combined with ADC value decreased within injured cerebral cortex,peripheral area of lateral ventricle and hippocampus regions.The injured range on DWI and ADC maps became extended with the time passing on.The ADC value of EG decreased to the lowest at 3 h and increased gradually after 6 h,and returned approximately normal at 12 h.In CG,there were no obvious changes on DWI and ADC maps.There was significant difference between EG and CG (P<0.05).［Conclusion］DWI imaging combined with ADC map can be used for the early detection of hypoxic-ischemic lesions.