Comparison of (18)F-FDG PET/CT and (99 m)Tc-MDP bone scintigraphy for detection of bone metastasis in osteosarcoma

We compared the diagnostic performance of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) and (99 m)Tc-methylene diphosphonate bone scintigraphy (BS) for the detection of bone metastasis in osteosarcoma. We retrospectively reviewed 206 patients with stage II–IV osteosarcoma treated with surgery and chemotherapy as well as at least one paired PET/CT and BS scan (defined as an examination). PET/CT and BS images were interpreted separately. When analyzing the diagnostic yield of a combination of PET/CT and BS (PET/CT+BS), an examination was considered positive if either PET/CT or BS scored positive. The final diagnosis was obtained from histological findings or clinical follow-up with imaging studies for at least 6 months. Diagnostic performances of PET/CT, BS, and their combinations were calculated. Out of 833 examinations in 206 patients, 55 with 101 lesions in 38 patients were confirmed as bone metastases. The sensitivity, specificity, and diagnostic accuracy were 95, 98, and 98 %, respectively, for PET/CT; 76, 97, and 96 %, respectively, for BS; and 100, 96, and 97 %, respectively, for PET/CT+BS in an examination-based analysis. Lesion-based analysis demonstrated that the sensitivity of PET/CT+BS (100 %) was significantly higher than that of PET/CT (92 %) or BS (74 %) alone. BS detected significantly less bone metastases in the growth plate region than outside the growth plate region (22 vs. 77 %). PET/CT is more sensitive and accurate than BS for diagnosing bone metastases in osteosarcoma. The combined use of PET/CT and BS improves sensitivity.