Staging investigations following the diagnosis of Ewing sarcoma may include chest computerized tomography (CT), technetium bone scintigraphy (bone scan), [F-18]-fluorodeoxy-D-glucose positron emission tomography (FDG-PET) scan, and bone marrow biopsy and aspiration (BMA/Bx). Each of these staging investigations provides complementary prognostic information, however the optimal combination of staging investigations is not clear.Procedure.
We conducted a retrospective study of 91 patients diagnosed with Ewing sarcoma and consecutively treated at our medical facilities between January 1, 2001 and December 31, 2011. We compared the radiologist's interpretations of staging FDG-PET and bone scans. We additionally compared the results of imaging evaluations to bilateral and unilateral BMA/Bx.Results.
We found FDG-PET and bone scan to have an examination-based concordance rate of 98% (one discordant case with a positive FDG-PET and negative bone scan). The region-based concordance rate for the imaging modalities was 97% for all cases and 63% for metastatic cases. The ipsilateral concordance rate for BMA/Bx was 98% with BMBx detecting metastases in seven cases and BMA detecting metastases in four cases. The left versus right concordance rates for BMBx and BMA were 98% and 97%, respectively. In all cases where bone marrow metastases were detected by BMA or BMBx, FDG-PET and bone scan detected osseous metastases.Conclusions.
Our study indicates FDG-PET may be sufficient for initial screening for osseous metastases and identified all patients who also have bone marrow metastases. If osseous metastases are detected, a bone scan can detect additional osseous lesions and BMBx may indicate prognostic bone marrow metastases.