Figure 21b. Recurrent colorectal carcinoma in a 55-year-old woman after surgical resection. FDG PET- CT was performed to evaluate for recurrence because of a rising level of carcinoembryonic antigen. (a) Axial contrast-enhanced CT image of the pelvis shows minimal presacral soft tissue at the surgical site (arrows). (b) Corresponding fused FDG PET-CT image shows intense hypermetabolism at the surgical site (arrow), which was due to local recurrence. Arrowhead = suture from surgery.