新型心肌灌注显像剂^(99)Tc^m-N-DBODC5在兔体内的生物分布

Study of Biodistribution Properties of a New Myocardial Imaging Agent ^(99)Tc^m-N-DBODC5

制备了99Tcm-N-DBODC5,并将其经静脉注射到新西兰白兔体内,进行活体显像,检测其活体生物分布及离体器官分布,研究99Tcm-N-DBODC5作为心肌灌注显像剂的可行性。活体生物分布结果显示,99Tcm-N-DBODC5的心肌摄取迅速,心肌摄取量低于99Tcm-MIBI,99Tcm-N-DBODC5的肝清除速度显著快于99Tcm-MIBI,在注射后30 min时心与肝的T/NT为0.98±0.52,已接近1,显著高于99Tcm-MIBI的心与肝的T/NT(0.56±0.19),P=0.007。60 min时,99Tcm-N-DBODC5的心与肝的T/NT达到高峰,为1.18±0.57,而99Tcm-MIBI仅为0.71±0.29。在180 min内,99Tcm-N-DBODC5的心与肝的T/NT维持在较高水平9。9Tcm-N-DBODC5的肺摄取低,清除快,心与肺的T/NT在180 min内保持在1.43±0.37以上,与99Tcm-MIBI无显著差别9。9Tcm-N-DBODC5的肝清除迅速,避免了肝内放射性对左室下壁的干扰,有利于实现早期显像。故99Tcm-N-DBODC有望成为一种生物分布特性较好的新的心肌灌注显像剂。

^99Tc^m-N-DBODC5 for intravenous injection was prepared. The labelling yield was 95.0% ±0. 52%. Sixteen New Zealand rabbits were involved and planar gamma imaging was performed at 10 time-point after injection of ^99Tc^m-N-DBODC5. The radioactivity changes of organs were calculated by regions of interest （ROD analysis. The 16 rabbits were divided into 4 groups and were sacrificed at 30, 60, 120, and 180 min after injection respectively. The activity for all excised organs were measured by 7-well counting for calculating radiouptake. Myocardial uptake for ^99Tc^m-N-DBODC5 is high. Though myocardial uptake was lower than ^99Tc^m-MIBI, the liver clearance for ^99Tc^m-N-DBODC5 was more rapid than that of ^99Tc^m-MIBI. As early as 30 min after injection, ^99Tc^m-N-DBODC5 heart-to-liver ratio is 0.98±0.52 versus 0. 56±0.19 for ^99Tc^m-MIBI （P〈0.01）. At 60 min post-injection, ^99Tc^m-N-DBODC5 heart-to-liver ratio improved to the peak value （1.18±0.57）, compared with 0.71±0.29 for ^99Tc^m-MIBI, P〈0.01. After 60 min, the heart-to-liver ratio of ^99Tc^m-N-DBODC5 was keeping at a high level until 180 min. ^99Tc^m-N-DBODC5 exhibited rapid lung clearance, similar to that of ^99Tc^m-MIBI. The biodistribution in the isolated organs demonstrated the same trend. The rapid ^99Tc^m-N-DBODC5 liver clearance may allow the earlier imaging, and overcome the photon scatter from the liver with high activity which interfered the inferoapical wall in myocardial images. ^99Tc^m-N-DBODC5 is a promising new myocardial perfusion imaging agent with superior biodistribution properties.