^(99)Tc^m-DTPA-Gd的制备及其生物学分布

Preparation and Biodistribution of ^(99)Tc^m-DTPA-Gd

应用99Tcm标记顺磁对比剂Gd-DTPA并研究其生物学分布特性。99Tcm在氯化亚锡还原下一步法标记Gd-DTPA,采用薄层纸层析法(TLC)分析标记率大于98%,室温放置6 h内放化纯稳定。三氯乙酸沉淀法测得99Tcm-DTPA-Gd在家兔血浆中的蛋白结合率为(3.80±0.25)%。正常昆明小鼠体内分布实验显示,注射99Tcm-DTPA-Gd后1 min血液的放射性摄取为(14.79±9.77)%ID/g,肾脏的摄取为(26.02±8.50)%ID/g;心、肝、脾和肺有少量分布,脑组织分布最少(<1%ID/g);注射99Tcm-DTPA-Gd 30～60 min后多数脏器的滞留小于1%ID/g。正常成年家兔注射99Tcm-DTPA-Gd后采用肾动态显像模式观察60 min内的分布和排泄,显示99Tcm-DTPA-Gd主要经肾脏排泄,摄取高峰时间约为5～10 min,半排时间约为10～20 min,其它脏器无特异性滞留。

To observe the biologic characteristics of Gd-DTPA labeled with 99Tcm,the labeled compounds were prepared by reducing 99Tcm in the presence of Gd-DTPA with stannous chloride.The labeling efficiency was measured by TLC（〉98%,and stable at room temperature within 6 h）.The plasma protein binding rate measured by the trichloroacetic acid method is（3.80±0.25）%.The bio-distribution in mice was observed by the blood sampling and other major organs that were taken out from mice at 1,5,10,15,30,and 60 min after intravenous injection of labeled compounds.The percentage of the injected dose per gram of tissues（%ID/g） of the blood and kidney are the highest level at 1 min after injection of 99Tcm-DTPA-Gd.They are（14.79±9.77）%ID/g and（26.02±8.50）%ID/g,respectively.Heart,liver,spleen and lung have a little distribution of radiopharmaceuticals,and brain has the lowest level uptake less than 1%.The deposition of 99Tcm-DTPA-Gd in other major organs was less than 1% at 30-60 min after injection.Renal dynamic scintigraphy in rabbits are administrated,and show that 99Tcm-DTPA-Gd is quickly excreted by kidney,and the time to peak is about 5-10 min,the half time of clearance is about 10-20 min.The animal experiments in vivo and in vitro show that 99Tcm-DTPA-Gd and 99Tcm-DTPA have the qualitatively similar biodistribution and excretion.99Tcm labeled Gd-DTPA may be a significant way not only to study its bio-distribution but also to directly observe its distribution and excretion by renal dynamic scintigraphy.