Evaluation of the effect of preoperative chemotherapy in bone sarcomas. ^99mTc-HMDP scintigraphy in 34 cases

We quantitatively analyzed images of ^99mTc-HMDP bone scintigraphy in 34 bone sarcomas before and after preoperative chemotherapy. The isotopic uptake was calculated as tumor-to-background ratio (TBR), and the changes in TBR before and after chemotherapy were calculated as the alteration ratio. The histological effect of preoperative chemotherapy was classified in 4 grades, according to Huvos. We defined good scintigraphic responders as cases having decreased uptake after chemotherapy, with an alteration ratio ≥ 60%. There was a positive correlation (Rho = 0.76, p < 0.001) between the histological effect and the alteration ratio. Of the 17 good histological responders, 13 showed a good scintigraphic response. The average alteration ratio in 17 cases with good response (68%) was higher than that in 17 cases showing poor response (-9.9%) (p < 0.001). 3 patients with pathologic fractures and 1 with primarily normal uptake showed false negative findings. The sensitivity of this method was 100% and the specificity was 81%.