Background: The purpose is to evaluate the accuracy of computed tomography (CT) in the pulmonary staging of osteosarcoma.
Patients and methods: Fifty-one patients presenting with osteosarcoma and at initial CT considered metastatic to the chest had lung surgery. Two teams of two senior radiologists independently reviewed all CT examinations. Their results were compared to the histological studies.
Results: One hundred nineteen CT's were reviewed. The 2 teams found 247 and 268 nodules on the initial. and 143 and 146 nodules on the preoperative CT. Histological studies confirmed metastatic nodules in 29 patients. Two hundred four nodules were excised and studied. One hundred nine were metastases. The 22 patients without metastases had 53 negative nodules removed. In the 29 patients with metastases, 151 nodules were removed, and 42 were non-metastatic. The positive predictive value was 53% with regard to 'nodules', and 57% with regard to 'patients'. Only 4 out of 13 patients with one nodule at surgery were metastatic, but all patients with more than 7 nodules were metastatic. The 46 cases with several available CT's, showed that no change in the number of nodules was more frequent in benign lesions. Other criteria revealed no significant difference.
Conclusion: CT positive predictive value is limited, but as surgery is the only way to cure metastatic patients, CT will still be used as the reference technique until a more specific approach can be found.