Initial Tc-99m diphosphonate uptake in mineralized and demineralized bone implants in rats

Radionuclide imaging has been suggested as a means to assess healing and viability of bone grafts and implants. This study deals with the in vivo uptake of 99mTc-MDP in the initial postoperative period in rats. Isogeneic or xenogeneic bone was implanted in subcutaneous pouches. The isogeneic grafts and implants were treated with saline or freeze-treated or demineralized. The xenogeneic implants consisted of Kiel bone or collagen sponge. One day after surgery, the accumulation of 99mTc after an intraperitoneal injection of 99mTc-MDP was seen in all grafts and implants containing bone mineral independent of prior treatment of the graft and implant. In implants composed of only the organic part of bone, no accumulation was observed. One prerequisite for accumulation of 99mTc-MDP is the presence of the inorganic phase. Thus, the interpretation of the initial postoperative scan is based on whether or not the graft or implant initially contained mineral.