Abstract: 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 ⁹⁹Tc^m, and its biologic characteristics were observed. The radiochemical purity and the stability of ⁹⁹Tc^m-Gd-DTPA-Dimeglumine were measured by TLC The labelling 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 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 ⁹⁹Tc^m-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 ⁹⁹Tc^m, 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.

Key words: DTPA, Gadolinium DTPA dimeglumine, bio-distribution, 99Tcm labeling

摘要： 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^m-Gd-DTPA-Dimeglumine。薄层色谱法（TLC）分析标记物的标记率＞95%，可在室温下稳定存放6 h，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-Gd-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，⁹⁹Tc^m-Gd-DTPA-Dimeglumine 主要经肾脏排泄，达高峰时间约5 min，半排时间约7 min。⁹⁹Tc^m标记Gd-DTPA-Dimeglumine 方法简单，标记效率高，Gd-DTPA-Dimeglumine 经⁹⁹Tc^m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⁹⁹Tc^m 和顺磁性金属元素Gd，并有望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。

关键词: DTPA, Gd-DTPA-二甲葡胺, 生物学分布, 99Tcm标记