Relative accretion of 99mTc-polyphosphate by forming and resorbing bone systems in rats: its significance in the pathologic basis of bone scanning.

The relative roles of osteogenesis andd osteolysis in the production of positive radionuclide images of skeletal lesions were investigated. The uptake of 99mTc-polyphosphate (Tc-PP) by each process was measured in an animal model that permitted bone formation and resorption to be studied independently. Ten rats received intramuscular implants of bone-forming demineralized matrix (DM) and resorbing devitalized bone (DV). Radiographs and Tc-PP scintiscans were made each week thereafter. At 6-10 weeks, the implants and normal bone samples were removed, counted for 99mTc, and examined histologically. The uptake of Tc-PP BY DM implants was first detected on images made 3 weeks after implanatation, and by DV implants, 1-2 weeks later. Serial radiography showed progressive calcification of DM an resorption of DV implants. Microscopic examinations of undecalcified sections, stained with a modified Goldner preparation, revealed vital-bone formation in the DM implants and osteoclastic resorption in the DV. Activity counts per gram of DM and DV implants were, respectively, 200% and 90% that of normal bone. Since only the bone-forming system (DM) accumulated Tc-PP at greater than normal concentrations, this study indicates that positive bone images of osteolytic lesions solely reflect compensatory osteogenic responses.