~(99m)Tc-帕米膦酸盐的制备及骨分布

为观察99mTc标记的帕米膦酸盐(Pamidronate,PAM)的骨分布特点,以氯化亚锡为还原剂,优化99mTc直接标记PAM的条件,研究SnCl2(Ⅱ)含量、配体用量、pH及反应时间对标记率的影响,确定了优化的标记条件;考察99mTc-PAM的体外稳定性;评价99mTc-PAM在正常鼠体内的生物分布,尤其是骨摄取情况,比较99mTc-PAM与99mTc-MDP在正常小鼠体内的骨摄取。实验结果表明,PAM的99mTc标记方法简单,标记率大于95%,标记物体外稳定性好。正常鼠体内分布实验发现,99mTc-PAM骨摄取很高,且滞留时间长,在血液中清除快,在体内主要通过肾代谢;正常大鼠SPECT显像骨组织清晰可见,具有很好骨显像效果。与99mTc-MDP在正常小鼠体内的生物分布结果比较表明,99mTc-PAM的骨放射性摄取及骨与血放射性摄取比在不同时相均优于99mTc-MDP。研究表明,99mTc-PAM具有理想的骨显像性能,可用于骨显像、骨损伤探测以及肿瘤骨转移检测等应用研究。

Preparation and Biodistribution of 99mTc-Pamidronate as Bone Imaging Agent

Labeling of Pamidronate (PAM) with ^99mTc was studied by a direct labeling method in the presence of SnCl₂•2H₂O as reducing agent. The influences of the concentration of SnCl₂•2H₂O, PAM concentration and pH value, reaction time on labeling yield were investigated. The optimum labeling was determined. The results showed that the radiochemistry purity of^99mTc-PAM was more than 95%. Biodistribution studies in normal mice and rats showed very high uptake of ^99mTc-PAM and long retain in bone.^99mTc-PAM was washed out from the blood very quickly. In addition, considerable uptake in the kidneys indicated this complex was excreted mainly by renal pathway. On the other hand, the radioactivity in liver, lung and heart was negligible. It could be known from SPECT images that^99mTc-PAM would be an excellent bone-imaging agent. Bone uptake of ^99mTc-PAM was higher than that of^99mTc-MDP in mice. This study suggested that^99mTc-PAM was a promising bone imaging agent and further study was worthwhile.