论文部分内容阅读
背景:有研究表明,弥散加权成像可以在脑缺血后数分钟即出现异常信号。目的:观察大鼠大脑中动脉脑缺血后表观弥散系数的表现及变化规律。设计:随机对照实验。单位:重庆医科大学临床学院神经内科。材料:实验于2004-04/07在重庆医科大学附属第一医院放射科完成,选择成年Wistar清结级大鼠18只。随机分为正常对照组,假手术组和脑缺血组,每组6只。方法:采用右侧大脑中动脉栓塞法制作脑缺血模型,假手术组栓塞线仅插入颈内动脉未深及大脑中动脉的起始处,正常对照组麻醉后不作任何处理。于术后7,15,30min,1,3,6,12,24h,3,7,15d,1,2个月做1HMRS检查,获得弥散加权成像和表观弥散系数值。主要观察指标:大鼠脑梗死区域和对侧半球相应区域表观弥散系数值的变化。结果:大鼠缺血组DWI于术后7min出现异常高信号,此时T1WI,T2WI扫描示正常。T1WI,T2WI于缺血后1～3h出现异常高信号,随时间的推移,异常高信号的区域扩大,12h后右侧基底节和额顶叶皮质梗死,以后梗死面积增加不明显。表观弥散系数值于7min时发现降低,30min时表观弥散系数明显升高,1h后开始降低,12h时降到最低水平,24h以后又开始上升,2个月时表观弥散系数值较最低水平约增加5倍,而且随访的2个月中表观弥散系数始终保持明显上升的趋势。相对表观弥散系数显示出相反的变化。结论:表观弥散系数均可以超早期揭示脑缺血的发生,同时对脑血管疾病慢性期也非常敏感。
Background: Studies have shown that diffusion-weighted imaging can display abnormal signals within minutes after cerebral ischemia. Objective: To observe the appearance and changes of apparent diffusion coefficient after middle cerebral artery occlusion in rats. Design: Randomized controlled experiment. SETTING: Department of Neurology, School of Clinical Medicine, Chongqing Medical University. MATERIALS: The experiment was performed at the Department of Radiology, the First Affiliated Hospital of Chongqing Medical University from April 2004 to July 2007. Eighteen adult Wistar rats were selected. Randomly divided into normal control group, sham operation group and cerebral ischemia group, 6 rats in each group. Methods: The right middle cerebral artery occlusion method was used to make the model of cerebral ischemia. The embolization line of the sham operation group was only inserted into the internal carotid artery not deep and the middle of the middle cerebral artery. The normal control group was given no treatment after anesthesia. 1H MRS were performed at 7, 15, 30 min, 1, 3, 6, 12, 24 h, 3, 7, 15 d, 1 and 2 months after operation to obtain diffusion weighted imaging and apparent diffusion coefficient values. MAIN OUTCOME MEASURES: Changes of apparent diffusion coefficients in the corresponding regions of cerebral infarction and contralateral hemisphere of rats. Results: DWI in rats with ischemia at 7min after the abnormal high signal, this time T1WI, T2WI scan showed normal. T1WI and T2WI showed abnormally high signal after 1 ~ 3h after ischemia. With the passage of time, the area of abnormally high signal increased. After 12h, the right basal ganglia and the parietal cortex infarcted, and the infarct size did not increase obviously. Apparent diffusion coefficient decreased at 7min, apparent diffusion coefficient increased significantly at 30min, decreased at 1h, reached the lowest level at 12h, then increased at 24h, and apparent diffusion coefficient at 2 months was the lowest The level of about 5 times increase, and the follow-up of 2 months, the apparent diffusion coefficient has remained a clear upward trend. Relative apparent diffusion coefficient showed the opposite change. Conclusion: Apparent diffusion coefficient can reveal the occurrence of cerebral ischemia in a very early stage and is also very sensitive to the chronic phase of cerebrovascular disease.