Gd—DTPA—Dimeglumine的^99Tc^m标记及其生物学特性

以氯化亚锡为还原剂，^99Tc^m一步法标记了顺磁对比剂Gd—DTPA-Dimeglumine（钆喷酸二甲葡胺），得到^99Tc^mGd-DTPA-Dimeglumine。薄层色谱法（TLC）分析标记物的标记率〉95％，可在室温稳定存放6h，放化纯度〉90％；三氯乙酸沉淀法测定^99Tc^m-Gd—DTPA-Dimeglumine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，^99Tc^m-G＆DTPA—Dimeglumine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1min摄取达高峰，注射后5min滞留率下降大于50％，注射后30～60min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，^99Tc^m-Gd—DTPA-Dimeglumine主要经肾脏排泄，达高峰时间约5min 半排时间约7min。^99Tc^m标记Gd-DTPA—Dimeglumine方法简单，标记效率高，Gd-DTPA—Dimeglumine经^99Tc^m怀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^99Tc^m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。

Preparation of 99Tcm-Gd-DTPA-Dimeglumine and its Biologic Characteristics

The purpose of this study was to evaluate the feasibility of Gd-DTPA-Dimeglumine, as a contrast enhancer in magnetic resonance imaging(MRI). Gd-DTPA-Dimeglumine was labeled with 99Tcm, and its biologic characteristics were observed. The radiochemical purity and the stability of 99Tcm-Gd-DTPA-Dimeglumine were measured by TLC The labelling yield of 99Tcm-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 99Tcm-Gd-DTPA-Dimeglumine was 2.25%±0.21%. The biodistribution in mice showed that 99Tcm-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 morn than 50% at 5 min after injection, and the brain and muscles have the lowest uptake rate less than 1%. The major organs have little uptake at 30-60 min after injection. Renal dynamic scintigraphy in rabbits were administrated via intravenous injection. The results indicated that 99Tcm-Gd-DTPA-Dimeglumine was quickly excreted by kidney, and the time to peak is about 5 min, the half time of clearance is about 7 min. It is a sample method with high labeling efficiency and radiochemical purity that Gd-DTPA-Dimeglumine labeled with 99Tcm, and its bio-distribution was not changed on the whole after labeled. The study indicated that DTPA as a bifunctional chelator may be linked with 99Tcm and Gd. So a type of new multimodality imaging agents with higher targeting characteristics, it could be applied both in SPECT and MRI scan.