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.