Introduction PET CT is a non-invasive imaging modality that is widely used in the imaging work up of malignant disease. It has been postulated that due to ¹⁸FDG accumulation in adenomatous polyps, PET CT using ¹⁸FDG may detect early premalignant colonic lesions. The aim of our study was to assess the performance of ¹⁸FDG PET CT in the detection of significant colonic lesions namely adenomas or villous adenomas >1 cm in size and to assess whether endoscopy in all patients with focal FDG colonic uptake on PET CT is justified by the detection rate.

Methods A retrospective review of patients who had ¹⁸FDG PET CT at the Pennine Acute Hospitals NHS Trust, Manchester as part of their staging for various cancers between February 2007 and October 2011 was conducted by a review of the reports of the examinations.

Results 1553 patients between the ages of 17 and 93 years (median age 55 years) had ¹⁸FDG PET CT performed during this period. Increased focal FDG uptake in the colon was detected in 179 of 1553 patients studied (11.5%). Endoscopic evaluation was performed in 71 (39.7%) of these patients, flexible sigmoidoscopy in 25 (35.2%) and colonoscopy in 46 (64.8%). Non-malignant pathology was found in 45 of 179 patients (25.1%); 17 (9.5%) were tubulovillous adenomas; 6 (3.4%) had villous adenomas; 9 (5.0%) were tubular adenomas; 4 (2.2%) hyperplastic polyps; 11 (6.1%) were normal colonic tissue and 1 (0.6%) was active inflammatory bowel disease. From the patients with increased ¹⁸FDG uptake in the colon, 19 (10.6%) were subsequently found to have adenocarcinoma on histology. This represents 26.8% of the 71 patients who received endoscopic evaluation.

Conclusion The presence of focal colonic ¹⁸FDG uptake on PET CT scan justifies endoscopic evaluation in all patients where treatment would be clinically appropriate.

Competing interests None declared.