Objective: 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.
Materials and methods: 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.
Results: 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%).
Conclusions: 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.