Early Prediction of Histopathological Tumor Response to Preoperative Chemotherapy by Tc-99m MIBI imaging in Bone and Soft Tissue Sarcomas Abbreviated title: Prediction of chemotherapeutic effect by Tc-99m-MIBI Original Manuscript

Purpose: Tc-99m-MIBI accumulates in only viable cells. In patients with bone and soft tissue sarcomas, preoperative chemotherapy is essential and the early prediction of the tumor response to chemotherapy would be beneficial for the planning of treatment strategy. The purpose of this study was to assess whether the change of Tc-99m-MIBI image from pre-chemotherapy to the early to middle of the chemotherapy can predict final histopathological tumor response as accurately as the change of the image after completion of chemotherapy. Methods: Seventy-three patients with bone and soft tissue sarcomas underwent Tc-99m-MIBI scintigraphy before chemotherapy and at least 2 times after the second or third or fifth chemotherapy. The change of the tracer uptake (∆UR) and perfusion (∆PI) from pre-chemotherapy to post-chemotherapy were compared with histologic response. Results: The sensitivity, specificity, and accuracy for the prediction of effective chemotherapy in ∆PI were 88%, 83%, 85% after 2nd, 85%, 72%, 78% after 3rd, and 81%, 71%, 76% after 5th chemotherapy, and those in ∆UR were 88%, 83%, 85% after 2nd, 85%, 92%, 89% after 3rd, and 94%, 77%, 85% after 5th chemotherapy, respectively. The area under the receiver operator characteristic curve of the ∆PI after 2nd, 3rd, and 5th chemotherapy were similarly good (0.842, 0.858, 0.811, respectively) and those of ∆UR were similarly excellent (0.915, 0.936, 0.931, respectively). Conclusion: In patients with bone and soft tissue sarcomas, the change of Tc-99m-MIBI image from pre-chemotherapy to early to middle of chemotherapy can predict the final histopathological tumor response to chemotherapy as accurately as the change of Tc-99m-MIBI image from pre-chemotherapy to the completion of the preoperative chemotherapy.