Study of biodistribution properties of a new myocardial imaging agent ^99mTc(N)(PNP5)(DBODC)⁺

^99Tc^mN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^mNDBODC5. The radioactivity channes of organs were calculated by regions of interest (ROI) 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 γwell counting for calculating radiouptake. Myocardial uptake for 99TcmNDBODC5 is high. Though myocardial uptake was lower than 99TcmMIBI, the liver clearance for ⁹⁹Tc^mNDBODC5 was more rapid than that of ⁹⁹Tc^mMIBI. As early as 30 min after injection, ⁹⁹Tc^mNDBODC5 hearttoliver ratio is 0.98±0.52 versus 0.56±0.19 for ^99Tc^mMIBI (P<0.01). At 60 min postinjection, ^99Tc^mNDBODC5 hearttoliver ratio improved to the peak value (1.18±0.57), compared with 0.71±0.29 for ⁹⁹Tc^mMIBI, P<0.01. After 60 min, the hearttoliver ratio of ⁹⁹TcmNDBODC5 was keeping at a high level until 180 min. ⁹⁹Tc^mNDBODC5 exhibited rapid lung clearance, similar to that of ⁹⁹Tc^mMIBI. The biodistribution in the isolated organs demonstrated the same trend. The rapid ⁹⁹Tc^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. ⁹⁹Tc^mNDBODC5 is a promising new myocardial perfusion imaging agent with superior biodistribution properties.