FLUORESCENCE ENDOSCOPIC IMAGING OF HUMAN COLONIC ADENOMAS

Background & Aims: Endoscopic screening for sporadic colorectal cancer relies in part on the detection of adenomatous polyps. Nonpolypoid ad enomas or flat dysplasia may go unrecognized by conventional endoscopy . This study attempted to develop and test a novel endoscopic method f or detecting polypoid and nonpolypoid colonic adenomas. Methods: Colec tomy specimens from 3 patients with familiar adenomatous polyposis con taining polypoid and nonpolypoid adenomas were illuminated with excita tion light at 351 and 364 nm. Endoscopic images of the net tissue fluo rescence emitted were collected over the spectral bandwidth from 400 t o 700 nm. Each raw image was corrected for differences in distance and instrument light collection efficiency by normalizing to a spatially averaged image. Intensity thresholding was then used to identify regio ns of diseased mucosa. Results: The average fluorescence intensity fro m normal mucosa was found to be greater than that from adenomas by a f actor of 2.2 +/- 0.6. The sensitivity and specificity for detecting a region of dysplasia varied with the threshold value selected. At a thr eshold of 75% of the average normal intensity, a sensitivity of 90% an d a specificity of 92% were achieved. Conclusions: Fluorescence images of colonic mucosa can be collected endoscopically, and dysplasia can be detected and localized with high sensitivity and specificity. These results show the potential of this technique to direct endoscopic bio psy.