Background: Peroral cholangioscopy (POCS) is valuable for assessing malignant biliary strictures; however, biliary drainage prior to POCS often hinders accurate diagnosis. Objectives: This retrospective study aimed to investigate the feasibility of POCS using a newly developed cholangioscope, CHF-B290, during initial endoscopic retrograde cholangiopancreatography (ERCP) for malignant biliary strictures. Methods: This multicenter retrospective study included patients who underwent initial ERCP for malignant biliary strictures at two institutions between January 2018 and March 2022. Patients who underwent initial ERCP with POCS were classified into the POCS group, and those without POCS were classified into the non-POCS group. To prevent post-POCS cholangitis, the original irrigation system for CHF-B290 was used in all POCS examinations. The primary endpoint was the rate of post-ERCP biliary infections, and the secondary endpoints were other ERCP-related complications, including pancreatitis, bleeding, and perforation. Results: Overall, 53 and 94 patients were included in the POCS and non-POCS groups, respectively. For the primary endpoint, the rate of post-ERCP biliary infection was not significantly different between the two groups (1.9% vs. 5.3%, p = 0.42). For the secondary endpoints, no significant differences were observed in the rates of post-ERCP pancreatitis (5.7% vs. 6.4%, p = 1.00) and other ERCP-related complications. The overall complication rate was 9.4% in the POCS group and 13% in the non-POCS group (p = 0.60). Conclusions: POCS during the initial ERCP for malignant biliary strictures is feasible.

Texture and color enhancement imaging (TXI) and red dichromatic imaging (RDI) modes are new image-enhancement options available on the EVIS X1 system (Olympus Corporation, Tokyo, Japan). TXI emphasizes slight differences in color tone and structural changes on the mucosal surface under normal light [1], whereas RDI may improve the visibility of deep blood vessels [2]. We previously reported the use of TXI- and RDI-mode cholangioscopy (CHF-B290, Olympus Corporation) in cholangiocarcinoma [3]. Here, we describe this technique in a patient with IgG4-related sclerosing cholangitis (IgG4-SC) and autoimmune pancreatitis (AIP). An 87-year-old woman presented with elevated liver enzymes and diffuse pancreatic enlargement ([Fig. 1], [Fig. 2]). Endoscopic retrograde cholangiopancreatography (ERCP) revealed segmental stenosis of the distal bile duct, preventing passage of the cholangioscope. A biliary stent was placed. Histopathology revealed no malignant findings; high IgG and IgG4 levels led to the diagnosis of AIP + IgG4-SC. Due to the patient’s age, stent replacement and stenosis reassessment were performed 2 months later without medication. The second ERCP showed slight improvement in stenosis, allowing passage of the cholangioscope. Cholangioscopy revealed partially dilated and slightly tortuous vessels without encasement or fusion [4] at the hilar bile duct. Dilated vessels were more clearly observed, and the fine surface structures of the thickened mucosa were more pronounced in TXI mode 1 than with white-light imaging. In RDI mode 3, the color of the bile disappeared and the dilated vessels were more strongly accentuated than with TXI. The mucosal surface was smooth, and no tumor vessels were observed at the stenosis ([Video 1]). The addition of TXI and RDI to cholangioscopy may therefore aid the diagnosis of IgG4-SC. A third ERCP 4 months later showed slight bile duct stenosis that did not require stenting; no adverse events or recurrence of symptoms were observed over the 10-month follow-up period. Video 1 Findings of the cholangioscopy using texture and color enhancement imaging mode 1 and red dichromatic imaging mode 3 in a patient with IgG4-related sclerosing cholangitis and autoimmune pancreatitis. Endoscopy_UCTN_Code_TTT_1AR_2AG Article published online: 30 August 2023 © 2023. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/) Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

Texture and color enhancement imaging (TXI) and red dichromatic imaging (RDI) modes are new image-enhancement systems available on the EVIS X1 (Olympus, Tokyo, Japan). TXI emphasizes slight differences in color tone and structural changes on the mucosal surface under normal-light observation and is expected to improve the observation performance of lesions [1]. On the other hand, RDI emphasizes the contrast of deep tissue and is expected to improve the visibility of deep blood vessels [2]. Especially in RDI mode 3, the color of bile disappears, making visualization easier. TXI and RDI modes are gaining popularity in the diagnosis of gastrointestinal cancer. However, TXI and RDI mode cholangioscopy (CHF-B290, Olympus) has not been reported for cholangiocarcinoma [3]. We describe the findings and characteristics of TXI mode 1 and RDI mode 3 cholangioscopy for cholangiocarcinoma. An 81-year-old man was admitted to the hospital with obstructive jaundice and cholangitis ([Fig. 1], [Fig. 2]). Endoscopic retrograde cholangiopancreatography was performed, revealing stenosis of the distal bile duct. A biliary stent was placed, cholangitis was treated, and histopathology revealed a cholangiocarcinoma. Cholangioscopy was performed to confirm the extent of superficial spreading. TXI mode 1 more clearly depicted the meandering tumor vessels along with caliber changes and the roughness of the tumor surface when compared to white-light imaging. In RDI mode 3, the color of bile disappeared and the tumor vessels were more accentuated than those in TXI ([Video 1]). Narrow-band imaging demonstrated good delineation of superficial tumor vessels [4], but the presence of bile made it difficult to observe the bile duct. Biopsies from the hilar region of the bile duct showed no malignancy, and a pancreatoduodenectomy was performed. Postoperative histopathology showed an irregular papillary epithelium with irregularly dilated tumor vessels ([Fig. 3]). Image-enhanced cholangioscopy is useful in diagnosing cholangiocarcinomas. Video 1 Demonstration of new image-enhanced cholangioscopy for the diagnosis of cholangiocarcinoma. Endoscopy_UCTN_Code_CCL_1AZ_2AC Article published online: 28 October 2022 © 2022. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/) Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany

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