Fig. 3.

A-H These transaxial fused ¹⁸F-FDG PET/CT images from a 10-year-old boy with Ewing sarcoma of the right fibula demonstrate areas of increased FDG uptake in the (A) shaft of the right femur, (B) left sacral ala, (C) left head of the femur, and (D) left iliac bone, suggesting metastatic lesions. Transaxial fused ¹⁸F-FDG PET/CT images of this patient at the same four levels 5 months after chemotherapy demonstrate decreased FDG uptake in the (E) shaft of the right femur, (F) left sacral ala, (G) left head of the femur, and (H) left iliac bone, which were previously showing high FDG uptake, confirming that these lesions were actually skeletal metastases from the primary tumor. This also gave us information that the tumor was responding to the given chemotherapeutic regimen, highlighting the utility of ¹⁸F-FDG PET/CT in assessing the patient’s response to treatment.