In vivo identification of colonic dysplasia using fluorescence endoscopic imaging

Background: Previous in vitro studies showed that autofluorescence images o f colonic mucosa collected endoscopically can be used to detect dysplasia w ith high sensitivity. This method is extended to the collection of fluoresc ence images of adenomatous polyps in vivo. Methods: Fluorescence images were collected during colonoscopy in 30 patien ts. A total of 12 adenomatous and 6 hyperplastic polyps were identified. A fiberoptic excitation probe, located in the instrument channel of the colon oscope, delivered 300 mW of near-ultraviolet light at lambda(ex) = 351 and 364 nm. Mucosal fluorescence in the spectral bandwidth between 400 and 700 nm was imaged, processed, and displayed with various likelihoods of associa ted dysplasia. Results: Adenomatous polyps exhibited decreased fluorescence intensity comp ared with adjacent mucosa with normal appearance. With the fluorescence thr eshold set to 80% of the average intensity of normal mucosa, a sensitivity of 83% for dysplasia identification was achieved. All hyperplastic polyps w ere correctly identified as being non-dysplastic. Optimal identification of dysplastic regions was obtained with the colonoscope oriented at a near-no rmal angle of incidence to the polyps. At higher angles of incidence, artif acts caused by illumination shadows were introduced. Conclusions: The dysplasia associated with adenomatous polyps can be identi fied in vivo by fluorescence imaging with high sensitivity, thus demonstrat ing the potential to guide endoscopic procurement of biopsy specimens.