[A new radiopharmaceutical for osteoarthral cartilage imaging: preparation and animals experiment of 99mTc-CS].

The objective of this research work is to prepare a new and reliable radiopharmaceutical for osteoarthral cartilage imaging. Chondroitin sulfate (CS) was labeled directly with 99mTc by "pretinning" method, the labeling efficiency was 79.30% +/- 1.72% and radiochemical purity was 90.12% +/- 1l.23% after filtration by use of asepsis filter membrane. The biodistribution of 99Tc-CS was studied at 10, 30 min and 1, 2, 3, 4, 5, 6, 7, 8, 9 h respectively after caudal vein injection in normal mice,which showed that the radiolabeled product was washed out from blood quickly, and it was mainly excreted through kidney, but 99mTc-CS had distinctive characteristic of philo- cartilage. Scintigraphy of 99mTc-CS was performed on the rabbit with ostarthritis at 5 h after intravenous injection; the scintigram was clear,and the focus showed increased radiopharmaceutical uptake. The radioactivity ratio of the injured/uninjured side (T/NT) calculated over the region of interest (ROI) was 3.0 +/- 0.6 (P < 0.05). These results indicate that 99mTc-CS is an easily prepared compound with the characteristic of high philo-cartilage and it may be a new ideal cartilage imaging agent.