摘要
目的应用增强MRI和病理学方法评价急性大脑中动脉（MCA）闭塞动物模型血脑屏障（BBB）的改变。材料与方法Wistar大鼠160只，采用随机数字表法将其分为两组（缺血再灌注组与永久缺血组各80只），其中76只模型制备成功且行有效MR增强检查。线栓法制作MCA闭塞模型，术后3、6、12、24、48及72h连续对模型动物进行T1WI、T2WI及增强T1WI扫描，测量双侧MCA供血区信号强度（SI），计算缺血脑实质增强率，并与相应时间点的电子显微镜所见对照。结果再灌注组3～72h强化出现率分别为92％、0％、20％、80％、87％与100％，SI增加率为70．1％、6．9％、48．9％、33．3％、38．9％及55．0％；永久缺血组3～72h强化出现率分别为0％、11％、25％、50％、67％及100％，SI增加率分别为7．9％、16．1％、16．7％、22．9％、57．6％及57．9％。3h时间点两组有明显差异（X^2=18．462，P=0．001）。再灌注组22只大鼠3h时间点注射对比剂后均出现长达21h的延迟强化。电镜检查再灌注组手术后3h见缺血区血管基底膜形态不整及血管周围间隙增宽，6～72h血管基底膜、内皮细胞及其间隙、血管周围间隙的改变逐渐加重；永久缺血组手术后3h血管内皮细胞与基底膜改变轻微，6h以后逐渐出现血管基底膜、内皮细胞及其间隙、血管周围间隙异常，72h时最为明显。术后48h后两组均见明显的新生血管。结论Gd—DTPA增强MRI是研究缺血后急性期BBB开放的理想手段。缺血再灌注与永久缺血强化表现不同，前者有独特的3h强化峰及该时间点延迟强化现象，增强MRI有可能区分二者。
Objective To evaluate the evolvement of blood brain barrier（BBB） in experimental middle cerebral artery（MCA） occulsion model with contrast MRI and pathology. Materials and Methods 160 Wistar rats were randomly divided into 2 groups, including reperfusion group （ n = 80） and permanent occlusion group （ n = 80）, Among of them, successful operation and effective contrast MR examination were made to 76 rats, A nylon thread was placed into MCA to induce acute cerebral artery occlusion model, T1WI, T2WI and contrast T1WI were continuously performed after operation at an interval of 3,6,12,24,28 and 72h respectively, The signal intensity（SI） of bilateral MCA fending areas on pre and post contrast T1WI was measured, and enhancement rate was calculated. The findings of electron microscopy were compared with MRI data. Results For reperfusion group, from 3h to 72h, the rates of enhancement of ischemic parenchyma were 92%, 0%, 20%, 80% , 87% and 100%, the rate of SI increment were 70.1%, 6.9%, 48.9%, 33,3%, 38,9% and 55,0% separately; for permanent occlusion group, with same time interval, the rates of ischemic parenchyma were 0 % , 11%, 25 %, 50 %, 67 % and 100 %, with rate of SI increment were 7,9%, 16.1%, 16,7%, 22,9%, 57,6% and 57,9% separately. There was significant difference Of the enhancement between two groups at 3h after operation（X^2 = 18.462, P = 0.001 ）. Delay enhancement lasting 21 hours after injection of contrast medium at 3h after operation was found in 22 rats of reperfusion group, At 3h after operation, the pathologic findings of reperfusion group included enlarged extravascular space and irregular basal membrane; the corresponding sequential pathologic findings were gradual increasing the abnormality of basal membrane, endothelial cells and theirs space, and extravascular space,For permanent occlusion group, there were slight changes about endothelial ceils and basal membrane at 3h after operation; however, gradual abnormalities were detected to basal membrane, endothelial cells an
出处
《临床放射学杂志》
CSCD
北大核心
2006年第11期1063-1068,共6页
Journal of Clinical Radiology
关键词
脑缺血
再灌注
血脑屏障
大鼠
磁共振成像
对比增强
Brain isehemia, reperfusion Blood-brain barrier Rat Magnetic resonance imaging Contrast enhancement
