The usefulness of a repeat study for differentiating between bowel activity and local tumor recurrence on FDG PET scans.

The importance of fluorodeoxyglucose (FDG) positron emission tomography (PET) in the evaluation of colorectal cancer is well established. Activity in the rectosigmoid region on an FDG PET scan may vary significantly, which may occasionally lead to difficulties in interpretation when assessing local recurrence of colorectal cancer. The authors present a case in which a repeat PET study performed after an enema 1 week later was useful for differentiating between normal bowel activity and local tumor recurrence. This repeat study obviated the need for surgical intervention, although the role of the enema in this case is unclear.