增强MRI评价可逆性血脑屏障开放的可靠性及价值

Evaluation of the reversible blood brain barrier opening by contrast enhanced MRI

目的评价增强ＭＲＩ在监测可逆性血脑屏障（ＢＢＢ）开放的可靠性及价值。方法３６只家兔被随机分为３组：Ａ、Ｂ两组分别经颈内动脉灌注２０％甘露醇和生理盐水，Ｃ组经耳缘静脉灌注２０％甘露醇。灌注后，立即用０．５Ｔ超导型ＭＲ机进行兔脑冠状位扫描，随后经耳缘静脉注入ＧｄＤＴＰＡ，迅速行同层间隙扫描（增强后５、１０、１５、２０分钟，之后每隔１０分钟），持续２小时。以该层双侧对称的脑实质为兴趣区，测得不同时间兴趣区信号强度（ＳＩ），求其增强率（％）。各组１０只兔于扫描前经耳缘静脉注入２％Ｅｖｅｎｓ蓝（２ｍｌ／ｋｇ），２小时后处死；另有６只分别于灌注后２．５、３小时注入Ｅｖｅｎｓ蓝，１０分钟后处死，取脑观察有无脑实质蓝染，以此来推测ＢＢＢ开放持续时间。所有脑标本送病理检查，并与对应层的ＭＲＩ进行比较。结果Ａ组１０只皆出现灌注侧脑实质增强及蓝染，Ｂ、Ｃ组无一只出现明显强化及蓝染。ＢＢＢ开放持续时间小于３小时。未发现死亡及脑实质病理改变。结论增强ＭＲＩ是监测ＢＢＢ开放过程、指导临床个体化用药的一种理想方法。

Purpose To identify the reliability and value of contrast enhanced MRI in monitoring the reversible blood brain barrier(BBB) opening. Methods Thirty six cases of rabbits are arranged randomly into 3 groups :Group A, B are infused respectively with 20% mannitol, normal saline into the internal carotid artery, and group C with 20% mannitol into vein. Following infusion, contrast enhanced MRI is performed intervally, and the percent enhancement of SI is calculated. Ten cases of each group are injected with 2% Evens blue intravenously prior to imaging. After 2 hours of infusion, all the animals are killed.Their brains are examined for the determination of evens blue distribution. In order to measure the lasting time of the BBB opening, the others of group A are also done respectively at 2.5, 3 hour after infusion. All brain specimens are sent for pathologic examination. Results Enhancement and staining are evident in ipsilateral hemisphere of group A. No significant enhancement and staining with Eevens blue are noted in group B, C. The lasting time of BBB opening is less 3 hours. Neither mortality nor pathologic change is found. Conclusion Enchanced MRI is a reliable tool to detect the BBB opening and to inspect clinician in treatment.