New technologies for the further advancement of ERCP

Background: The capabilities of conventional endoscopic retrograde cholangiopancreatography (ERCP) are hampered by several limitations. Newly developed adjunct technologies such as single operator peroral cholangiopancreatoscopy (SOPCP) and new imaging techniques could overcome some of these limitations, but their role in common clinical practice have not yet been established. Aims: To assess the diagnostic and therapeutic yield of SOPCP in the diagnosis and treatment of biliopancreatic disease. To investigate patient-related risk factors for post procedural pancreatitis (PPP) following single-operator peroral pancreatoscopy. To determine the feasibility and potential clinical yield of bimodal ERCP. To assess radiation dose in cone beam ERCP. Methods: In paper I, All SOPCP procedures performed at Karolinska University Hospital between March 2007 and December 2014 were included in this study and each procedure’s diagnostic yield and therapeutic value was evaluated using a predefined 4 grade assessment scale. In paper II, all consecutive patients that underwent single operator pancreatoscopy (SOPP) at Karolinska University Hospital between April 2015 and Nov 2020 were included. The Swedish Registry for Gallstone Surgery and ERCP (GallRiks) was used to retrieve patient data and preprocedural imaging was reviewed in consensus by two senior radiologists. Pancreatic gland morphology and main pancreatic duct (MPD) diameter were evaluated as risk factors for PPP using uni- and multivariate logistic regression. In paper III, patients undergoing conventional ERCP had a previous T2-weighted magnetic resonance cholangiopancreatography (MRCP) sequence aligned and fused with the two-dimensional image generated from the fluoroscopy c-arm unit in real time and data regarding feasibility and clinical yield was retrieved. In paper IV, radiation exposure data from conventional ERCP procedures and cone beam ERCP (CB-ERCP) procedures performed between February 2016 and June 2017 at a tertiary high volume endoscopy unit was analyzed. CBERCP cases used either the standard exposure protocol ‘DR’ or the modified low dose exposure protocol‘DR Care’. Results: During the study period in paper I, 365 SOPCP procedures were performed. SOPCP was found to be of pivotal importance (grade 4) in 19% of cases, and of great clinical significance (grade 3) in 44% of cases. SOPCP did not affect clinical decision-making or alter clinical course (grade 1 and 2) in 37% of cases. In paper II, Postprocedural pancreatitis occurred in 15 (23%) of patients during the 30-day follow up. Univariate analysis of risk factors for PPP showed a significant association with chronic pancreatitis (OR 0.28 95% CI 0.08-0.92), insertion of a pancreatic stent (OR 0.28; 95% CI 0.08-0.95) and the ratio between MPD and pancreatic gland thickness in the body of pancreas (OR 1.14; 95% CI 1.03-1.28). In a multivariate regression model, the association between an increased body MPD/gland ratio in pancreatic body and PPP remained significant (OR 1.26; 95% CI 1.06-1.57) after adjustments for confounders including chronic pancreatitis. In paper III, 13 patients underwent bimodal ERCP for bile duct stricture, complex cholelithiasis or ductal leakage. Bimodal ERCP was feasible in all 13 cases, and image quality was assessed as “good” in 11 patients (85%). Bimodal ERCP aided in visualizing the lesion of interest (77 %), assisted in understanding the 3D anatomy of the biliopancreatic ductal system (62 %), and aided in finding a favorable position for the c-arm (38%) for subsequent therapeutic intervention. In paper IV, 728 conventional ERCP procedures were performed and 42 cases utilized CBERCP. The median total dose area product (DAP) was 48.9 Gycm2 for CB-ERCP procedures using the DR exposure protocol and 19.7 Gycm2 for CB-ERCP procedures using the DR care exposure protocol. The median total DAP was 6.5 Gycm2 when conventional ERCP was used. Conventional ERCP generated a significantly reduced total DAP compared to both CBERCP using the ‘DR’ exposure protocol (U=908, p < 0.001) and CB-ERCP using the ‘DR care’exposure protocol (U=3823, p < 0.001). Conclusions: SOPCP has a high impact on management of patients with complex cholelithiasis, indeterminate biliary strictures and pancreatic cystic lesions in a tertiary care setting, but the procedure contributes to a considerable risk of adverse events. There is an association between the pancreatic gland thickness and MPD diameter in the pancreatic body with the risk of developing PPP after SOPP. Bimodal ERCP is feasible and can aid in understanding biliary anatomy and visualizing the lesion of interest. Its future area of use may lie in the assessment and treatment of complex intrahepatic biliary disease. Cone beam asssisted ERCP procedures are associated with higher total radiation doses than conventional ERCP procedures, but it is possible to decrease radiation doses to acceptable levels with adjustments of exposure protocols. These adjustments do not compromise the capabilities of cone beam ERCP to provide enhanced intraprocedural guidance

Full Issue: Volume 13, Issue 1 - Winter 2018

Full Issue: Volume 13, Issue 1 - Winter 201

Fusion of colour contrasted images for early detection of oesophageal squamous cell dysplasia from endoscopic videos in real time

Standard white light (WL) endoscopy often misses precancerous oesophageal changes due to their only subtle differences to the surrounding normal mucosa. While deep learning (DL) based decision support systems benefit to a large extent, they face two challenges, which are limited annotated data sets and insufficient generalisation. This paper aims to fuse a DL system with human perception by exploiting computational enhancement of colour contrast. Instead of employing conventional data augmentation techniques by alternating RGB values of an image, this study employs a human colour appearance model, CIECAM, to enhance the colours of an image. When testing on a frame of endoscopic videos, the developed system firstly generates its contrast-enhanced image, then processes both original and enhanced images one after another to create initial segmentation masks. Finally, fusion takes place on the assembled list of masks obtained from both images to determine the finishing bounding boxes, segments and class labels that are rendered on the original video frame, through the application of non-maxima suppression technique (NMS). This deep learning system is built upon real-time instance segmentation network Yolact. In comparison with the same system without fusion, the sensitivity and specificity for detecting early stage of oesophagus cancer, i.e. low-grade dysplasia (LGD) increased from 75% and 88% to 83% and 97%, respectively. The video processing/play back speed is 33.46 frames per second. The main contribution includes alleviation of data source dependency of existing deep learning systems and the fusion of human perception for data augmentation

Computer-assisted diagnosis of wireless-capsule endoscopic images using neural network based techniques

Computerised processing of medical images can ease the search of the representative features in the images. The endoscopic images possess rich information expressed by texture. In this paper schemes have been developed to extract texture features from the texture spectra in the chromatic and achromatic domains for a selected region of interest from each colour component histogram of images acquired by the new M2A Swallowable Capsule. The implementation of advanced learning-based schemes and the concept of fusion of multiple classifiers have been also adopted in this paper. The preliminary test results support the feasibility of the proposed methodology