Labeling of ceftriaxone for infective inflammation imaging using 99mTc eluted from 99Mo/99mTc generator based on zirconium molybdate

Abstract

Zirconium molybdate gel was prepared by mixing 99Mo, produced from 98Mo(n,γ) reaction and Zr solutions in nitrate media with excess H2O2, and used as the base material for 99Mo/99mTc generator. The prepared generator showed a good performance. 99mTc eluted from the prepared generator passed the quality control tests with specifications meeting the requirements of European and US Pharmacopeias. The 99mTc eluate was used for labeling of cephalosporin analogue, ceftriaxone, which was then assessed for infection imaging in a mouse model. 99mTc-ceftriaxone was prepared at pH 9 with a radiochemical yield of 95±2% by adding 99mTc to 30 mg ceftriaxone in the presence of 50 μg SnCl2·2H2O. Biodistribution studies in mice were carried out using experimentally induced infection in the left thigh using E. coli. Both thighs of the mice were dissected and counted to evaluate the ratio of bacterial infected thigh/contralateral thigh. 99mTc-ceftriaxone showed high uptake in the infectious lesion (T/NT =5.6±0.6 at 4 h post injection). The abscess to normal muscle ratio indicated that 99mTc-ceftriaxone could be used for infection imaging. Besides, in vitro studies showed that 99mTc-ceftriaxone can differentiate between bacterial infection and sterile inflammation