目的 利用动态增强MRI评价A2A腺苷受体激动剂瑞加德松对兔血-脑屏障的可逆性开放作用及最佳时间窗.方法 将20只新西兰大白兔分为实验组和对照组,每组10只,分别经耳缘静脉注入瑞加德松和生理盐水,立即行脑冠状位扫描;随后注入Gd-二乙撑三胺五乙酸(DTPA)行同层间隙扫描(增强后5、10、15、20 min,之后每隔10 min),持续2 h,测量不同时间感兴趣区(ROI)的信号强度(SI),计算SI增强率(％).观察兔脑伊文思蓝染色情况.采用配对t检验分析数据.结果 实验组注入瑞加德松后5 min脑ROI的SI增强率为(40.93±3.70)％,明显升高,30 min左右达到最大值[(43.03±3.62)％],持续至50 min缓慢下降,80 min左右趋于平稳;各时间点实验组SI增强率均高于对照组(t值:6.88～20.28,均P<0.05),且实验组脑组织明显蓝染.结论 瑞加德松可暂时可逆性开放血-脑屏障,最佳时间窗为注射后10～50 min.%Objective To evaluate the opening level and optimal time window of the blood-brain barrier induced by adenosine A2 receptor agonist ( Lexiscan) via dynamic enhanced MRI. Methods Twen-ty New Zealand white rabbits were divided into experiment group ( group A, n=10) and control group ( group B, n=10) . Rabbits in group A were injected with Lexiscan and rabbits in group B were injected with physiological salt via ear vein, then the coronary scanning was performed. Contrast enhanced MRI was performed at different time points ( 5, 10, 15, 20 min, and then every 10 min, until 2 h) following the in-fusion of Gd-diethylene triamine pentaacetic acid (DTPA). The signal intensity (SI) of region of interest ( ROI) was measured and the percent enhancement of SI was calculated. Evens blue staining results in brain tissues were observed. Pair t test was used to analyze the data. Results The percent enhancement of SI in group A significantly increased to (40. 93±3.70)％ at 5 min, reached the maximum of (43.03±3.62)％ at 30 min, slowly decreased until 50 min, and got to a stable level at almost 80 min. At each time point, the per-cent enhancement of SI in group A was significantly higher than that in group B ( t values:6.88-20.28, all P<0. 05) . The staining was evident in group A. Conclusions Lexiscan can open blood-brain barrier tem-porarily and reversibly, and the optimal opening time window is 10-50 min post-injection.
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