TL-201 SCINTIGRAPHY TO ASSESS EFFECT OF CHEMOTHERAPY IN OSTEOSARCOMA

Imaging results in patients with high-grade osteosarcoma of the extrem ities were reviewed to determine whether scintigraphic appearance corr elated with histologic response to preoperative chemotherapy. Methods: Histologically, the percent tumor necrosis in specimens from 30 patie nts were classified into three grades: grade 1 = necrosis less than 60 %, grade 2 = 60%-89% necrosis and grade 3 = diffuse necrosis greater t han 90% based upon whole transverse sections. Scintigraphically, we an alyzed (TI)-T-201 uptake before and after preoperative chemotherapy. T he changes in the tumor-to-background ratio were defined by an alterat ion ratio. Results: Of the 11 patients with a grade 1 response, the ra tio showed -67.1% +/- 45.4% (mean +/- s.d.). Of the 9 patients with a grade 2 response, the ratio showed 37.9% +/- 29.9% of the 10 patients with a grade 3 response the ratio showed 105.5% +/- 12.4%. The ratios correlated well with the histologic grades (p < 0.0001; analysis of va riance). Conclusion: Thallium-201 scintigraphy accurately assesses the effect of chemotherapy on osteosarcoma.