Gd-DTPA-Dimeglumine的^(99)Tc^m标记及其生物学特性

Preparation of ^(99)Tc^m-Gd-DTPA-Dimeglumine and its Biologic Characteristics

以氯化亚锡为还原剂,99Tcm一步法标记了顺磁对比剂Gd-DTPA-Di meglumine(钆喷酸二甲葡胺),得到99Tcm-Gd-DTPA-Di meglumine。薄层色谱法(TLC)分析标记物的标记率>95%,可在室温稳定存放6 h,放化纯度>90%;三氯乙酸沉淀法测定99Tcm-Gd-DTPA-Di meglumine的体外血浆蛋白结合率为2.25%±0.21%。小鼠体内生物分布结果显示,99Tcm-Gd-DTPA-Di meglumine主要经肾脏排泄,脑和肌肉组织摄取最少,所有脏器在注射后1 min摄取达高峰,注射后5 min滞留率下降大于50%,注射后30~60 min标记药物在主要脏器内滞留很少。家兔肾动态显像结果显示,99Tcm-Gd-DTPA-Di meglumine主要经肾脏排泄,达高峰时间约5 min,半排时间约7 min。99Tcm标记Gd-DTPA-Di meglumine方法简单,标记效率高,Gd-DTPA-Di meglumine经99Tcm标记后其生物学性质基本未改变。本实验表明可以通过双功能螯合剂DTPA同时链接放射性核素99Tcm和顺磁性金属元素Gd,并有望在此基础上合成一种具有较好靶向性又可同时进行核医学SPECT和MRI增强扫描的显像剂。

The purpose of this study was to evaluate the feasibility of Gd-DTPA-Dimeglumine, as a contrast enhancer in magnetic resonance imaging（MRI）. It was labeled with ^99Tc^m, and its biologic characteristics was observed. The radiochemical purity and the stability of ^99Tc^m-Gd_DTPA-Dimeglumine were measured by TLC. The labeling yield of ^99Tc^m- Gd-DTPA-Dimeglumine was 〉95 % and stable for at least 6 h at room temperature with the radiochemical purity more than 90%. The plasma protein binding rate of ^99Tc^m-Gd-DTPA- Dimeglumine was 2.25%±0. 21%. The biodistribution in mice showed that ^99Tc^m-Gd-DTPA-Dimeglumine was excreted through kidney. The time of the highest uptake in all of the major organs was at 1 min after injection, and the decrease of deposition was more than 50% at 5 min after injection, and the brain and muscles had the lowest uptake rate which was less than 1%. The major organs had little uptake at 30-60 min after injection. Renal dynamic scintigraphy in rabbits were administrated via intravenous injection. The results indicated that ^99Tc^m Gd-DTPA-Dimeglumine was quickly excreted by kidney, and the time to peak was about 5 min, the half time of clearance was about 7 min. It was a sample method with high labeling yield and radiochemical purity that Gd-DTPA-Dimeglumine labeled with ^99Tc^m and its biodistribution was not changed on the whole after labeled. The study indicated that DTPA as a bifunctional chelator may be linked with ^99Tc^m and Gd. As a type of new multimodality imaging agents with higher targeting characteristics, it could he applied both in SPECT and MRI scan.