Preparation and Biological Study on a Novel Bone Imaging Agent ⁹⁹Tc^m-HBIDP

To obtain a maximum radiolabeling yield, the labeling parameters for ⁹⁹Tc^m-HBIDP were optimized. Chemical and physical properties and biodistribution studies in mice for ⁹⁹Tc^m-HBIDP were performed. The optical labeling parameters are found as follows: pH=6, m(SnCl₂•2H₂O)=100μg, m(HBIDP)=5mg, A(⁹⁹Tc^mO₄^-)=55.5MBq at room temperature for 15min and the radiochemical purity is more than 95% and it is stable within 6h in vitro at room temperature. The octanol-water partition coefficients of ⁹⁹Tc^m-HBIDP (lg P) are -2.17 and -2.28 at the pH value of 7.0 and 7.4, respectively. The plasma protein binding ratio of ⁹⁹Tc^m-HBIDP is (31.41±1.25)%. In the biodistribution studies, ⁹⁹Tc^m-HBIDP exhibits a relatively high uptake in bone and much lower uptake in soft tissues and shows rapid clearance from soft tissues. Besides, the uptake of ⁹⁹Tc^m-HBIDP in heart, liver and spleen is much lower than that of ⁹⁹Tc^m-ZL. These preliminary studies indicate that ⁹⁹Tc^m-HBIDP has significant potential as a novel bone imaging agent.