Evaluation of autofluorescence colonoscopy for the detection and diagnosis of colonic polyps

Colorectal cancer is the second most common cause of death in the United Kingdom. Most cancers are believed to arise within preexisting adenomas. Although colorectal adenomas have a clear neoplastic potential, hyperplastic polyps do not. It, therefore, would be helpful to be able to differentiate between different polyps at a colonoscopy. Autofluorescence (AF) endoscopy has been developed to enhance conventional white light (WL) endoscopy in the diagnosis of GI lesions.

The aim of the present study was to evaluate whether AF colonoscopy can facilitate endoscopic detection and differentiation of colorectal polyps.

Patients were invited to attend for colonic assessment with both AF and WL endoscopy. AF readings, pictures, and biopsy specimens were taken of any visible pathology and of any high AF areas.

Gartnavel General Hospital, Glasgow, U.K.

A total of 107 patients were assessed.

Each patient was assessed with AF and WL colonoscopy.

An AF intensity ratio (AIR) was calculated for each polyp (ratio of direct polyp AF reading/background rectal AF activity).

A total of 75 polyps were detected: 54 adenomatous and 21 hyperplastic polyps. Colorectal adenomas had a significantly higher AIR compared with hyperplastic polyps (median, interquartile range): adenoma (3.54, 2.54-5.00] versus hyperplastic (1.60, 1.30-2.24); P = .0001). When using an AIR with the empirically cutoff value of 2.3, AF endoscopy had a sensitivity of 85% and a specificity of 81% at distinguishing adenomatous polyps from hyperplastic polyps.

AF colonoscopy may be a valuable tool for the visual distinction between adenomatous and hyperplastic polyps.