Application of the alteration uptake ratio of 99mTc-MIBI scintigraphy for evaluating the efficacy of neoadjuvant chemotherapy in osteosarcoma patients

Background: We aimed to semi-quantitatively evaluate using technetium-99m methoxyisobutylisonitrile (Tc-99m-MIBI) scintigraphy, the efficacy of neoadjuvant chemotherapy in osteosarcoma (OS) patients. Methods: A hundred and two patients with OS were retrospectively included in this study. All of them underwent Tc-99m-MIBI scintigraphy before and after neoadjuvant chemotherapy. Semi-quantitative parameters including the uptake ratio (UR) and alteration of uptake ratio (AUR) were calculated for each patient. According to tumor necrosis rate (TNR) [1], patients were classified into three group: a) Poor response group (grade I, TNR: less than 50%), b) Partial response group (grade II, TNR: 50%-89%) and c) Good response group (grade III, TNR: greater than 90%). The linear regression analysis of the AUR versus TNR was carried out. Results: Poor response, partial response and good response were found in 30, 52 and 20 patients, respectively. In the poor-response group the URpre and URpost were 1.68 +/- 0.44 and 1.83 +/- 0.71, respectively and the AUR was -0.02 +/- 0.33. In the partial-response group the URpre and URpost were 2.42 +/- 1.42 and 1.59 +/- 0.71, respectively and the AUR was 0.28 +/- 0.18. In the good-response group the URpre and URpost were 2.58 +/- 0.61 and 1.21 +/- 0.16, respectively and the AUR was 0.46 +/- 0.10. There was a statistically significant difference of the AUR between poor-response and partial-response groups (P<0.01) and also between the poor-response and good-response groups (P<0.01). The linear regression analysis of the AUR versus TNR showed a significantly positive correlation (r=0.76). Conclusion: The AUR was significant after neoadjuvant chemotherapy in the partial-response group and in the good-response group. Furthermore, it exhibited a positive correlation with TNR. All results indicated that Tc-99m-MIBI scintigraphy can be used to evaluate neoadjuvant chemotherapy for OS patients.