Improving Colonic Surface Visualization

Colonoscopy can miss as many as 22% of polyps partly because of its failure to expose mucosa in inaccessible areas (e.g., on the proximal sides of folds and flexures). Researchers recently simulated colonoscopy using computed tomography colonography flythroughs to determine how much colonic mucosa is visualized by colonoscopes with varying angles of view. CT colonography datasets were reviewed from 20 patients (mean age, 64; 40% men) who had symptoms suggestive of colorectal cancer and had been recruited for a study of antispasmodics during 2001 and 2002. A computer-generated centering line was used to simulate the path of the colonoscope, and the field of view could be adjusted from 0° to 180°.

The mean total colonic surface area was 2743±759 cm². A standard 140° angle of view exposed 86.6%±3.3% of the colonic surface area (range, 80%–93%), and a 170° view exposed 92.2%±3.3% (range, 88%–96%). The authors also assessed the Third Eye Retroscope, a catheter that is placed down the instrument channel of the colonoscope and that automatically retroflexes, providing a simultaneous 135° reverse-angle view. The combination of the 140° forward view plus the 135° retroflexed view exposed 98.7%±0.5% of the mucosa (range, 98%–99%). Combining a 170° colonoscope view with the Third Eye Retroscope view did not reveal significantly more surface area (98.9%±0.4%; range, 98%–99%).