The relationship between the biliary morphological changes observed in magnetic resonance cholangiopancreatography and pancreaticobiliary diseases

Objective: One of the most common causes of morbidity and mortality in hepatopancreaticobiliary surgeries are complications related to the bile ducts. Preoperative detection of biliary variations is important to reduce morbidity and mortality rates. Magnetic resonance cholangiopancreatography (MRCP) is a non-invasive, non-ionizing, and reliable method for demonstrating normal bile duct anatomy and variations. In this retrospective study, we aimed to demonstrate the prevalence of intrahepatic and extrahepatic bile duct and pancreatic duct variations in our population, investigate the relationship between various morphological changes observed in patients and pancreaticobiliary diseases. Materials and Methods: This study is a descriptive cross-sectional study that retrospectively examined 1141 patients who presented to our hospital between January 1, 2022, and December 31, 2023, due to abdominal pain and jaundice, and underwent upper abdominal MRI and MRCP. The patients ages, bilirubin values, and surgical history were recorded. Sureka et al.'s classification system was used for intrahepatic and extrahepatic bile duct variations, while Mortele et al.'s classification system was used for pancreatic duct variations. Bile duct diameters were measured, and bile duct dilation typifications were performed according to Griffin et al.'s study. Diameter cutoff points for bile duct dilation were determined in patients with elevated direct bilirubin levels. The relationship between the identified morphological changes and primary pancreaticobiliary malignant diseases (cholangiocarcinoma, pancreatic cancer, periampullary tumors) and primary benign diseases of the biliary system (cholelithiasis/choledocholithiasis, cholangitis, primary sclerosing cholangitis, benign biliary stricture, choledochal cyst) were examined. A significance level of p<0.05 was considered for statistical analysis, and SPSS 26 software was used. Results: Of the 927 patients included in the study, 414 were male and 513 were female. The mean age was 58.4 (range 7-96), with a mean age of 57.8 for females and 59.1 for males. Benign or malignant diseases were not observed in 211 patients (22.8%), while approximately 77.2% had at least one of the benign or malignant diseases we identified. Typical biliary anatomy, including type 1 right hepatic duct, type a left hepatic duct, and cystic duct with right lateral insertion, was identified in 117 patients. At least one variation was present in 810 patients. The most common anatomical variations were type 1 right hepatic duct (60.2%), type a left hepatic duct (80.6%), cystic duct with right lateral insertion (58.3%), and descending pancreatic duct course (39.7%). Significant associations were found between the presence of gallstones/sludge, male gender, pancreatic duct and bile duct dilation, variations in right hepatic duct, pancreatic duct course and configuration, and pancreaticobiliary malignant diseases. Additionally, an association was demonstrated between types of bile duct dilation and pancreaticobiliary malignancy, with thinning of the common bile duct ending being a normal finding, and a crescent-shaped filling defect seen distally in the common bile duct being significant for choledocholithiasis. Furthermore, smooth sudden obstruction of the common bile duct was generally associated with tumors originating from the pancreatic head, segmental bile duct dilation often raised suspicion of cholangiocarcinoma, and asymmetric irregular bile duct changes were predominantly seen in cholangiocarcinoma. Conclusion: In the evaluation of biliary tract, MRCP imaging is a non-invasive and gold standard procedure. Detection and reporting of variations in biliary tract and pancreatic duct with preoperative or pre-interventional MRCP will reduce morbidity and mortality. Additionally, identifying morphological changes in pancreaticobiliary system will facilitate patient monitoring and early detection of potential diseases.