A Clinical Study to Limit Physiologic Intestinal FDG Uptake Uptake on PET-CT Scans

Patients who undergo PET-CT scans to look for cancer are given an intravenous contrast (FDG) that is taken-up by active cells such as cancer cells. This contrast can then be seen in the body using the PET-CT scanner. However, cells in the colon also take up the FDG, and can produce "false positive" signals from the colon. Our hypothesis is that much of this signal comes from bacteria that are present in high concentrations in the colon. If this is the case, using an antibiotic to suppress the activity of bacteria may improve the ability of PET-CT to distinguish abnormal cells from normal cells in the colon.