[Nuclear medicine prediction of histologic tumor response of osteosarcoma].

The prediction of histologic tumor response to preoperative chemotherapy was assessed by quantitative scintigraphic follow-up examinations of 54 osteosarcomas. Tumor/non-tumor scintimetry using 99mTc labeled diphosphonates allowed accurate prediction of tumor response in 28 of 30 tumors (accuracy = 93%) after completion and in 10 of 12 osteosarcomas (accuracy = 83%) at the half-way stage of preoperative chemotherapy evaluating only those tumors which showed convergent changes of tumor/non-tumor ratios in the perfusion and the mineral phase. At the half-way stage, however, evaluation of chemotherapy effects was complicated in 12 of 23 osteosarcomas by diverging T/NT ratios. In contrast, quantification and mapping of the tumor plasma volume and 99mTc MDP plasma clearance predicted the histologic tumor response to chemotherapy in 12 of 13 tumors (accuracy = 92%) after completion and in all 11 cases (accuracy = 100%) at the half-way stage.