Figure 11.

Diffuse uptake in pelvis. FDG PET Axial image (A) demonstrates diffuse increased uptake in central pelvis posterior to bladder that may be consider normal. The corresponding CT (B) showed a soft tissue mass with central air at the suture lines in a 56-year-old female patient with previous history of rectal cancer and had a complete response to chemotherapy. She was referred for restaging due to weight loss and the combined PET/CT Axial (C) image suspected a metastatic lesion despite diffuse uptake. MRI of pelvis was performed, and the Axial, coronal, and sagittal planes (D–F) confirmed the suspicious and showed overt enhancement of the soft tissue mass (G) that is consistent with metastasis.