Improvement Of Choledochoscopy: Chromoendocholedochoscopy, Autofluorescence Imaging, Or Narrow-Band Imaging

Past and present results concerning assessment of choledochoscopy using chromoendoscopy, autofluorescence imaging (AFI), or narrow-band imaging (NBI) are summarized herein. On chromoendocholedochoscopy using methylene blue, cancer was stained dark blue. Interestingly, normal bile duct had dimple signs that are a significant feature of non-neoplastic mucosa. First-generation AFI (laser-induced fluorescence endoscopy-gastrointestine system) and system of autofluorescence endoscopy made it possible to detect neoplastic lesions as dark green-black lesions, although the image was insufficient. The sensitivity, specificity and diagnostic accuracy of white light illumination and AFI were 88.0%, 87.5%, 87.7%, and 100%, 52.5%, 70.8%, respectively. In contrast, the recently developed NBI system made it possible to emphasize the imaging of certain features such as mucosal structures and mucosal microvessels. NBI showed not only clear neoplastic findings such as irregular mucosa or tortuous tumor vessel, but also non-neoplastic findings such as smooth surface mucosa or dimple sign. In conclusion, the diagnostic power of chromoendoscopy and AFI were low, but NBI is expected to become the new-generation diagnostic tool for biliary tract diseases.