Uptake and localization of 99mTc-methylene diphosphonate in mouse osteosarcoma.

The localization of 99mTc-methylene diphosphonate (99mTc-MDP) in mouse osteosarcoma was studied using a skeletal scintigraphic method and macro- and microautoradiographic methods. On the skeletal scintigraph, the tumor showed a high uptake of 99mTc-MDP and its concentration was about 20 times as high as the value seen in the muscular tissue. The macroautoradiography showed high activity in the tumor bone region and little activity in the nonossified region. On the microautoradiography, the activity of 99mTc-MDP was localized in the mineralized matrix of tumor bone and was almost nil in the nonmineralized matrix (osteoid) and the tumor cells. These findings indicate that the mineralization of the tumor bone matrix plays an important role in 99mTc-MDP uptake in osteosarcoma.