Whole-body MRI vs bone scintigraphy in the staging of Ewing sarcoma of bone: a 12-year single-institution review

Objective To compare whole-body MRI (WB-MRI) at 1.5/3T and bone scintigraphy in the skeletal staging of Ewing sarcoma (ES) of bone. Methods All patients with a histological diagnosis of ES of bone between 2007 and 2018 were retrospectively reviewed. The analysis included gender, mean age, skeletal distribution, and prevalence of skeletal metastases on WB-MRI and bone scintigraphy. Results The study group comprised 182 patients with a mean age of 18.0 years (range 2-56 years), 126 males and 56 females. Skeletal metastases were detected overall in 30 patients (16.5%), in 23 of 96 patients (24%) who underwent WB-MRI, and in 20 of 118 patients (16.9%) who underwent bone scintigraphy. Of 71 patients who underwent both WB-MRI and bone scintigraphy, skeletal metastases were detected on both modalities in 13 (18.3%), while in 4 patients, skeletal metastases were identified on WB-MRI alone. There were no patients in whom skeletal metastases were identified on bone scintigraphy alone. Of 13 patients with skeletal metastases who underwent both studies, WB-MRI showed a greater number of metastatic foci in 10 (76.9%). However, scintigraphy was superior to WB-MRI in detecting skull vault lesions, but did show false-positive results around the long bone growth plates. Conclusion WB-MRI is more sensitive than bone scintigraphy in detecting skeletal metastases in ES of bone, with the exception of skull vault metastases. Consideration should be given to replacing bone scintigraphy with WB-MRI.