18F-FDG PET detection of colonic adenomas

The adenomatous polyp of the colon is clinically important as a precursor of colonic cancer. The aim of this preliminary study was to evaluate the potential usefulness of (18)F-FDG PET for detecting adenomatous polyps of the colon.

We performed a retrospective study of 110 subjects who underwent both PET study and total colonoscopy. On nonattenuation-corrected PET images, focal distinct FDG accumulation along the large intestine was considered a positive finding, and the PET results were compared with colonoscopic findings. Histology and adenoma size were determined by polypectomy.

Fifty-nine adenomatous polyps, 5-30 mm in size, were found in 30 subjects by total colonoscopy. PET findings were positive for 14 of the 59 adenomas (24%). The positivity rate for PET images rose with the increase in size of the adenomas; it was 90% in adenomas (9/10) that were > or =13 mm. The overall false-positive rate was 5.5% (6/110 subjects).

Increased glucose metabolism is observed in colonic adenomas, and detectability with PET increases with the increase in adenoma size. Adenomas are premalignant lesions, and it is important to realize that colonic adenomas may be found incidentally during an FDG PET study.