Improvement of Choledochoscopy: Chromoendocholedochoscopy, Autofluorescence Imaging, or Narrow‐band Imaging

Abstract

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.

Can image-enhanced cholangioscopy distinguish benign from malignant lesions in the biliary duct?

“…Hoffman et al reported that with POCS, a neoplastic mucosa was depicted as an irregular mucosa with inhomogeneous staining, whereas a non-neoplastic mucosa without inflammation was shown as having a weak and homogenous staining, and an inflamed mucosa as having a dark-blue staining pattern [17]. We reported our initial experience with video PTCS (ECN-1530, 5-mm outer diameter and 2-mm working channel; Pentax Co., Ltd.) using methylene blue [16].…”

“…It is possible to apply the currently available AFI system (CV-260SL/CV-290 processor, CVL-260SL/CVL-290SL light source; Olympus) to the aforementioned videocholangioscope [16]. AFI is a novel imaging technology in which endogenous fluorophores in the tissues are stimulated when the mucosa is illuminated by a short-wavelength light and a fluorescent light of a longer wavelength.…”

“…8 a waiting period of 2-3 minutes, and the bile duct lumen is continuously washed by irrigation of saline solution through the accessory channel during the observation [15][16][17].…”

“…After manipulation of the imaging signals, a normal mucosa appears green but neoplastic lesions appear dark green or black owing to the difference in the autofluorescence intensity. To obtain better images, saline solution is used for continuous irrigation [16,29,30].…”

“…A new video cholangioscope and an ultraslim endoscope can provide an excellent image; however, image-enhanced cholangioscopy (IEC) has also been evaluated for a better diagnostic yield [15][16][17]. POCS has been indicated for the imaging diagnosis of an indeterminate biliary stricture or a filling defect, mucosal tumor extension of cholangiocarcinoma, and biopsy under direct visualization [18].…”