[Bone scintigraphy in assessing the success of chemotherapy in osteosarcoma]

During preoperative chemotherapy regional 99mTc-MDP clearance by tumor and healthy bone as well as tumor blood flow were determined in 13 patients with osteosarcoma. The results were compared to histologic regression grades. After good response (tumor vitality less than 10%) tumor blood flow normalized and regional 99mTc-MDP clearance decreased by 66% (range 56-82%). After poor response to chemotherapy (tumor vitality greater than 10%) tumor blood flow remained increased, whereas regional 99mTc-MDP clearance was unchanged or increased except in one patient. After 4-7 weeks of chemotherapy tumor viability was accurately assessed in 8 of 9 patients (89%) by means of regional 99mTc-MDP clearance. Tumor viability could be evaluated also by simple tumor/non-tumor ratios. A decrease of 99mTc-MDP clearance by more than 20% indicated an effective chemotherapy with a specificity of 80%. After 10-13 weeks of chemotherapy the specificity was improved including the results of tumor blood flow determination.