| Objective To investigate the clinical usefulness of 201T1 chloride scintigraphy in the differential diagnosis of various musculoskeletal tumors. Methods 201T1 chloride scintigraphy was performed to diagnose the malignancy of bone and soft tissue tumors by visual and quantitative assessment in 36 patients (23 malignant lesions and 13 benign lesions). Planar images were obtained in the early phase (5 min after injection) and the delayed phase (120 min). By visual assessment a tumor was considered malignant if high accumulation was found in the tumor in the early phase and the accumulation was confirmed in the delayed phase. Tumors didn't meet these criteria were considered benign. For quantitative assessment, the ROI (region of interest) uptake ratios of the tumor to the contralateral normal tissue in the early phase (URe) and in the delayed phase (URd), the ROI uptake ratio of the delayed phase to the early phase of the tumor (URd/URe) were obtained. Six patients with osteosarcomas were evaluated by 20IT1 scintigraphy both pre- and post-chemotherapy, and pathologic changes were graded on the basis of percent tumor necrosis as defined histologically. And tumor necrosis rate (TNR) histologically was compared with changes in the 201T1 scintigraphic study. All 29 bone lesions of malignancy or benign, were accepted 99mTc-methylene-diphosphonate (99mTc-MDP) bone scan simultaneously. Results In comparison with benign tumors, malignant tumors showed longer retention or more increased uptake of the 201T1 in the lesions on delayed images. Quantitative assessment was performed for all 36 cases. The URe of 23 malignant and 13 benign lesions was 3.797 + 2. 756 and 1.264 + 0. 336, respectively, and the URe of malignant lesions was significantly higher than that of benign lesions (r=4.351,/?<0.001). The URd of 23 malignant and 13 benign lesions was 2.469+1. 18 and 1.106 + 0. 186, respectively, the results demonstrated a significant difference (t=5.421,/?<0.001). If the tumor having an URe greater than 1.65 was assumed to be malignant, the percentage sensitivities, specificities, and accuracy of 201T1 for differentiating malignant lesions from benign lesions was 95.65%, 92.31%, and 94.44% versus 95.65%, 100%, and 97.22% respectively for URd >1.50. In 6 cases of osteosarcomas with the preoperative chemotherapeutic treatment, 201T1 scintigraphic changes showed concordance with TNR, planar images of 201T1 of 5 responders with TNR>90% showed decreased uptake in the tumor lesions. Conclusions 201T1 scintigraphy is very useful for evaluating the location and extent of tumor and differentiating malignant from benign bone and soft tissue tumors. The URe is important for quantitative assessment, but a delayed image is necessary for visual and quantitative assessment. Serial 201T1 scintigraphy, with quantitative analysis of alterations in 201T1 uptake, may provide a quantitative and objective measure of the effect of preoperative chemotherapy in patients withosteosarcomas.[Keywords]scintigraphy, 201T1, 99mTc-MDP;bone and soft tissue,malignant or benign; osteosarcoma,preoperative chemotherapy... |
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