Conflicting reports about the localization of 99mTc-MDP in bone and cartilage are found in the literature. Possible binding sites include hydroxyapatite and non-osteoid matrix such as immature collagen. The present study used autoradiographs of demineralized and non-demineralized growth sites in young mice to demonstrate localization of 99Tc-MDP, and consequently 99mTc-MDP, in mineralizing cartilage and bone. Uptake of the isotope was seen in mineralizing bone and cartilage, associated with the mineral in contrast to the organic phase. The results indicate that bone seeking radiopharmaceutical uptake (BSRU) may detect alterations in the rate of mineralized phase in growth sites and thus has the potential to disclose skeletal growth disorders.
Animals Autoradiography