Evaluation of magnifying endoscopy using narrow band imaging using exvivo bile duct (with video)

Background and Aim Detailed endoscopic findings of the bile duct mucosa, even of the non-neoplastic mucosa, have not yet been established. The aim of the present study was to compare a currently used video cholangioscope (CCS) with a magnifying endoscope (ME) that is commonly used for the gastrointestinal tract, for visualization of the bile duct mucosa. Methods Ten freshly resected common bile ducts were used in this study. We observed the non-neoplastic bile duct mucosa with CCS and ME, and carried out both conventional white light imaging and narrow band imaging. After histological diagnosis, the 10 specimens were classified into three categories according to the degree of histological inflammation: normal to mild, moderate, and severe. Then, we examined the relationship between the magnifying endoscopic findings and the histopathological findings. Results In eight of the 10 cases, the visualization obtained with CCS was inferior to that obtained by ME. Five specimens were classified as normal to mild inflammation, and many oval-shaped, depressed areas and a fine, regular network of the microvessels were observed by ME on the mucosal surfaces of these specimens. The remaining specimens were classified as moderate or severe inflammation, and the aforementioned findings could not be clearly visualized. Conclusion CCS does not allow visualization of the bile duct mucosa with high sensitivity. Oval-shaped depressed areas and a fine, regular network of microvessels are characteristic endoscopic features of non-neoplastic bile duct mucosa without inflammation.