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Objective To compare the PET/CT and CT images of lower extremity long bone osteosarcoma, and to explore their performance in detecting distant/local metastases of osteosarcoma and in clinical staging of the lesions. Methods Fourteen patients with biopsy-confirmed lower extremity long bone osteosarcoma were enrolled in the present study. All patients underwent CT and PET/CT examination before operation. The image characteristic of tumors and bone marrow, lung metastases loci were analyzed. Results The mean maximum standard uptake value (SUVmax) of the primary lesions in this group was 10.68 (ranging 3.7-21.1). PET/CT found that the mean SUVmax value in metastasis group was significantly higher than that in non-metastasis group (11.94 vs 8.01, P<0.05). PET/CT also found 6 cases of bone marrow cavity metastases, and CT only found 2 cases. PET/CT detected 3 cases of lung metastases, and CT only found 2 cases. The accuracy of PET/CT in detecting the bone marrow metastases of osteosarcoma was significantly higher than that of CT (P=0.088 67<0.1). PET/CT showed no significant difference in detecting lung metastases compared with CT. Compared with CT, PET/CT increased the TNM stage of 4 patients (P<0.05). Conclusion Compared with CT, PET/CT has a better performance in demonstrating the tumor involvement, in detecting bone marrow metastasis of osteosarcoma, and in tumor staging. The SUVmax value can help to predict the prognosis of patients with osteosarcoma.
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Objective To investigate the 18F-FDG PET/CT features of clear cell sarcoma (CCS) of soft tissue. Methods Ten patients with pathologically confirmed CCS were enrolled in the present study. All patients underwent preoperative 18F-FDG PET/CT scanning, and the image findings and clinical characteristics of the tumors were analyzed. Results The mean maximum standard uptake value (SUVmax) of the primary lesions was 6.52(range, 5-9.6) in the patients. PET/CT revealed lung metastasis in 7 patients, soft tissue metastases in 5, and regional lymph node metastases in 3, with no brain/bone/liver metastases. CT findings showed lung metastases in 6 cases and soft tissue metastasis in one. Conclusion CCS 18F-FDG PET/CT image lacks specificity, but it can better demonstrate the extent and metastases of CCS, helping the accurate, timely, and more targeted therapy.