Imaging of Biliary Tree Abnormalities.

Pathologic conditions of the biliary system, although common, can be difficult to diagnose clinically. Challenges in biliary imaging include anatomic variants and the dynamic nature of the biliary tract, which can change with age and intervention, blurring the boundaries of normal and abnormal. Choledochal cysts can have numerous appearances and are important to diagnose given the risk of cholangiocarcinoma potentially requiring surgical resection. Choledocholithiasis, the most common cause of biliary dilatation, can be difficult to detect at US and CT, with MRI having the highest sensitivity. However, knowledge of the imaging pitfalls of MRI and MR cholangiopancreatography is crucial to avoid misinterpretation. Newer concepts in biliary tract malignancy include intraductal papillary biliary neoplasms that may develop into cholangiocarcinoma. New paradigms in the classification of cholangiocarcinoma correspond to the wide range of imaging appearances of the disease and have implications for prognosis. Accurately staging cholangiocarcinoma is imperative, given expanding curative options including transplant and more aggressive surgical options. Infections of the biliary tree include acute cholangitis or recurrent pyogenic cholangitis, characterized by obstruction, strictures, and central biliary dilatation. Inflammatory conditions include primary sclerosing cholangitis, which features strictures and fibrosis but can be difficult to differentiate from secondary causes of sclerosing cholangitis, including more recently described entities such as immunoglobulin G4-related sclerosing cholangitis and COVID-19 secondary sclerosing cholangitis. The authors describe a wide variety of benign and malignant biliary tract abnormalities, highlight differentiating features of the cholangitides, provide an approach to interpretation based on the pattern of imaging findings, and discuss pearls and pitfalls of imaging to facilitate accurate diagnosis. ©RSNA, 2024 Supplemental material is available for this article.

Acquisition of epithelial plasticity in human chronic liver disease.

For many adult human organs, tissue regeneration during chronic disease remains a controversial subject. Regenerative processes are easily observed in animal models, and their underlying mechanisms are becoming well characterized1-4, but technical challenges and ethical aspects are limiting the validation of these results in humans. We decided to address this difficulty with respect to the liver. This organ displays the remarkable ability to regenerate after acute injury, although liver regeneration in the context of recurring injury remains to be fully demonstrated. Here we performed single-nucleus RNA sequencing (snRNA-seq) on 47 liver biopsies from patients with different stages of metabolic dysfunction-associated steatotic liver disease to establish a cellular map of the liver during disease progression. We then combined these single-cell-level data with advanced 3D imaging to reveal profound changes in the liver architecture. Hepatocytes lose their zonation and considerable reorganization of the biliary tree takes place. More importantly, our study uncovers transdifferentiation events that occur between hepatocytes and cholangiocytes without the presence of adult stem cells or developmental progenitor activation. Detailed analyses and functional validations using cholangiocyte organoids confirm the importance of the PI3K-AKT-mTOR pathway in this process, thereby connecting this acquisition of plasticity to insulin signalling. Together, our data indicate that chronic injury creates an environment that induces cellular plasticity in human organs, and understanding the underlying mechanisms of this process could open new therapeutic avenues in the management of chronic diseases.

Normal morphometry of the biliary tree in pediatric and adult populations: A systematic review and meta-analysis.

PURPOSE: This study aimed to characterise the normal morphometry of the biliary tree in pediatric and adult populations, through a systematic review and meta-analysis. METHODS: This study, conducted using the PRISMA guidelines and registered with PROSPERO, searched MEDLINE, EMBASE, SCOPUS and Web of Science databases up to October 2022, and updated to August 2023. Studies that reported extractable data on diameter and length of the right, left and common hepatic ducts (LHD, RHD and CHD), and common bile duct (CBD) were included. Quality of the included studies were assessed using the Anatomical Quality Assessment (AQUA) tool. Statistical analysis included subgroup analyses according to sex, age, geographical location, and imaging modality. RESULTS: In total, 60 studies were included, of which 44 studies reported adequate data for meta-analysis on 23,796 subjects. Overall, the pooled mean diameter of the CBD was 4.69 mm (95 % CI: 4.28-5.11). Significant differences were found between pediatric (1.32 mm, 95 % CI: 1.03-1.61) and adult (4.97 mm, 95 % CI: 4.67-5.27) subjects, as well as US (3.82 mm, 95 % CI: 3.15-4.49) and other imaging modalities, including MRI (6.21 mm, 95 % CI: 4.85-7.57) and ERCP (7.24 mm, 95 % CI: 6.08-8.40). The CBD diameter measured significantly larger distally (5.20 mm, 95 % CI: 4.60-5.80) than proximally (4.01 mm, 95 % CI: 3.51-4.51). CONCLUSIONS: The results obtained from this evidence-based study may guide the establishment of standardised reference values and ranges of the normal biliary tree in pediatric and adult populations and aid clinical understanding.

Forward genetics combined with unsupervised classifications identified zebrafish mutants affecting biliary system formation.

Impaired formation of the biliary network can lead to congenital cholestatic liver diseases; however, the genes responsible for proper biliary system formation and maintenance have not been fully identified. Combining computational network structure analysis algorithms with a zebrafish forward genetic screen, we identified 24 new zebrafish mutants that display impaired intrahepatic biliary network formation. Complementation tests suggested these 24 mutations affect 24 different genes. We applied unsupervised clustering algorithms to unbiasedly classify the recovered mutants into three classes. Further computational analysis revealed that each of the recovered mutations in these three classes has a unique phenotype on node-subtype composition and distribution within the intrahepatic biliary network. In addition, we found most of the recovered mutations are viable. In those mutant fish, which are already good animal models to study chronic cholestatic liver diseases, the biliary network phenotypes persist into adulthood. Altogether, this study provides unique genetic and computational toolsets that advance our understanding of the molecular pathways leading to biliary system malformation and cholestatic liver diseases.

Determining the patency of biliary tracts in dogs with gallbladder mucocele using near-infrared cholangiography with indocyanine green.

Cholecystectomy is indicated for gallbladder mucoceles (GBM). Evaluating the patency of the biliary duct and precise biliary tree visualization is crucial for reducing the risk of compromised bile flow after surgery. Therefore, intraoperative cholangiography (IOC) is recommended during cholecystectomy to prevent biliary tract injury. Although indocyanine green (ICG) cholangiography has been extensively reported in human medicine, only one study has been conducted in veterinary medicine. Therefore, this study aimed to demonstrate the use of ICG for IOC to identify fluorescent biliary tract images and determine the patency of the common bile duct during cholecystectomy in dogs. This study comprised 27 dogs, consisting of 17 with gallbladder mucoceles (GBM) and 10 controls, specifically including dogs that had undergone elective cholecystectomy for GBM. ICG injection (0.25 mg/kg) was administered intravenously at least 45 minutes before surgery. During the operation, fluorescent images from cholangiography were displayed on the monitor and obtained in black-and-white mode for the comparison of fluorescence intensity (FI). The FI values of the gallbladders (GBs) and common bile duct (CBD) were measured using FI analyzing software (MGViewer V1.1.1, MetapleBio Inc.). The results demonstrated successful CBD patency identification in all cases. Mobile GBM showed partial gallbladder visibility, whereas immobile GBM showed limited visibility. Additionally, insights into the adequate visualization of the remaining extrahepatic biliary tree anatomy were provided, extending beyond the assessment of CBD patency and gallbladder intensity. Our study demonstrates the potential of fluorescent IOC using intravenous injection of ICG for assessing the patency of the cystic duct and common bile duct during cholecystectomy in patients with GBM, eliminating the need for surgical catheterization and flushing of the biliary ducts. Further research is warranted to investigate and validate the broader applicability of ICG cholangiography in veterinary medicine.

The dysregulation of biliary tract microflora is closely related to primary choledocholithiasis: a multicenter study.

Bile microecology changes play an important role in the occurrence and development of choledocholithiasis. At present, there is no clear report on the difference of bile microecology between asymptomatic patients with gallbladder polyps and choledocholithiasis. This study compared bile microecology between gallbladder polyp patients and patients with choledocholithiasis to identify risk factors for primary choledocholithiasis. This study was conducted in 3 hospitals in different regions of China. Bile samples from 26 patients with gallbladder polyps and 31 patients with choledocholithiasis were collected by laparoscopic cholecystectomy and endoscopic retrograde choledocholithiasis cholangiography (ERCP), respectively. The collected samples were used for 16S ribosomal RNA sequencing and liquid chromatography mass spectrometry analysis. The α-diversity of bile microecological colonies was similar between gallbladder polyp and choledocholithiasis, but the ß-diversity was different. Firmicutes, Proteobacteri, Bacteroidota and Actinobacteriota are the most common phyla in the gallbladder polyp group and choledocholithiasis group. However, compared with the gallbladder polyp patients, the abundance of Actinobacteriota has significantly lower in the choledocholithiasis group. At the genera level, the abundance of a variety of bacteria varies between the two groups, and Enterococcus was significantly elevated in choledocholithiasis group. In addition, bile biofilm formation-Pseudomonas aeruginosa was more metabolically active in the choledocholithiasis group, which was closely related to stone formation. The analysis of metabolites showed that a variety of metabolites decreased in the choledocholithiasis group, and the concentration of beta-muricholic acid decreased most significantly. For the first time, our study compared the bile of gallbladder polyp patients with patients with choledocholithiasis, and suggested that the change in the abundance of Actinobacteriota and Enterococcus were closely related to choledocholithiasis. The role of Pseudomonas aeruginosa biofilm in the formation of choledocholithiasis was discovered for the first time, and some prevention schemes for choledocholithiasis were discussed, which has important biological and medical significance.

BiliQML: a supervised machine-learning model to quantify biliary forms from digitized whole slide liver histopathological images.

The progress of research focused on cholangiocytes and the biliary tree during development and following injury is hindered by limited available quantitative methodologies. Current techniques include two-dimensional standard histological cell-counting approaches, which are rapidly performed, error prone, and lack architectural context or three-dimensional analysis of the biliary tree in opacified livers, which introduce technical issues along with minimal quantitation. The present study aims to fill these quantitative gaps with a supervised machine-learning model (BiliQML) able to quantify biliary forms in the liver of anti-keratin 19 antibody-stained whole slide images. Training utilized 5,019 researcher-labeled biliary forms, which following feature selection, and algorithm optimization, generated an F score of 0.87. Application of BiliQML on seven separate cholangiopathy models [genetic (Afp-CRE;Pkd1l1null/Fl, Alb-CRE;Rbp-jkfl/fl, and Albumin-CRE;ROSANICD), surgical (bile duct ligation), toxicological (3,5-diethoxycarbonyl-1,4-dihydrocollidine), and therapeutic (Cyp2c70-/- with ileal bile acid transporter inhibition)] allowed for a means to validate the capabilities and utility of this platform. The results from BiliQML quantification revealed biological and pathological differences across these seven diverse models, indicating a highly sensitive, robust, and scalable methodology for the quantification of distinct biliary forms. BiliQML is the first comprehensive machine-learning platform for biliary form analysis, adding much-needed morphologic context to standard immunofluorescence-based histology, and provides clinical and basic science researchers with a novel tool for the characterization of cholangiopathies.NEW & NOTEWORTHY BiliQML is the first comprehensive machine-learning platform for biliary form analysis in whole slide histopathological images. This platform provides clinical and basic science researchers with a novel tool for the improved quantification and characterization of biliary tract disorders.

Three-dimensional magnetic resonance cholangiography is superior to two-dimensional single-shot magnetic resonance cholangiography for visualization and image quality of the feline and canine biliary tract: A postmortem study.

Magnetic resonance cholangiography (MRC) is an established diagnostic tool for noninvasive assessment of the biliary tract in humans. It has also been found to be feasible in companion animals, but no published studies have compared MRC sequences in veterinary medicine. The present study is part of a prospective, observational, analytical investigation on MR cholangiopancreatography performed on the donated bodies of 12 cats and eight dogs. The main aim of this study was to compare the images of 2D-SSh-TSE-MRC and 3D-TSE-MRC sequences for visualization and image quality of the feline and canine biliary tract. Both sequences are T2-weighted and noncontrast. Three independent readers scored the visibility of four segments of the biliary tract, namely the gallbladder (GB), cystic duct, common bile duct (CBD), and extrahepatic ducts, and the image quality of the two MRC sequences using five-point Likert scales. Wilcoxon signed-rank test was used to compare the scores between the MRC sequences separately for cats and dogs. Inter- and intraobserver agreements were measured using Gwet's AC2 with linear weighting. The 3D-TSE-MRC images were scored significantly higher than the 2D-SSh-TSE-MRC for both visibility and image quality (P < .001-.016 for cats, P = .008-.031 for dogs); the only exception was GB in dogs. In both cats and dogs, interobserver agreement for segment visibility and image quality ranged from slight to substantial in 2D-SSh-TSE-MRC and from poor to almost perfect in 3D-TSE-MRC. Most of the assessments (73% for segment visibility and 66% for image quality) had substantial to almost perfect intraobserver agreement. Findings from the current study support the use of 3D-TSE-MRC over 2D-SSh-TSE-MRC for evaluation of the feline and canine biliary tract, but further studies on live animals are warranted.

Proteomic analysis of serum extracellular vesicles from biliary tract infection patients to identify novel biomarkers.

Biliary tract infection (BTI), a commonly occurring abdominal disease, despite being extensively studied for its initiation and underlying mechanisms, continues to pose a challenge in the quest for identifying specific diagnostic biomarkers. Extracellular vesicles (EVs), which emanate from diverse cell types, serve as minute biological entities that mirror unique physiological or pathological conditions. Despite their potential, there has been a relatively restricted exploration of EV-oriented methodologies for diagnosing BTI. To uncover potent protein biomarkers for BTI patients, we applied a label-free quantitative proteomic method known for its unbiased and high-throughput nature. Furthermore, 192 differentially expressed proteins surfaced within EVs isolated from individuals afflicted with BTI. Subsequent GO and KEGG analyses pinpointed Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) and Crumbs homolog 3 (CRB3) as noteworthy biomarkers. Validation via data analysis of plasma-derived EV samples confirmed their specificity to BTI. Our study leveraged an unbiased proteomic tool to unveil CEACAM1 and CRB3 as promising protein biomarkers in serum EVs, presenting potential avenues for the advancement of diagnostic systems for BTI detection.

Features of biliary tract diseases in ketamine abusers: a systematic review of case reports.

BACKGROUND AND AIMS: Anesthesiologists prefer ketamine for certain surgeries due to its effectiveness as a non-competitive inhibitor of the N-methyl-D-aspartate receptor in the brain. Recently, this agent has also shown promise as an antidepressant. However, ketamine can cause hallucinogenic effects and is sometimes abused as an illicit drug. Ketamine abuse has been associated with liver and bile duct complications. This systematic study aims to better understand cholangiopathy in ketamine abusers by reviewing case reports. METHODS AND MATERIAL: In this systematic review, a comprehensive literature search was conducted with the terms "biliary tract diseases" and "ketamine". Case reports and case series of adult patients with documented ketamine abuse and reported cholangiopathy or biliary tract disease were included. We extracted the data of relevant information and the results were reported through narrative synthesis and descriptive statistics. RESULTS: A total of 48 studies were initially identified, and 11 studies were finally included in the review. The mean age of the patients was 25.88 years. Of the 17 patients, 64.7% were men. Symptoms often included abdominal pain, nausea, and vomiting. Most patients were discharged with improved symptoms and liver function. Common bile duct dilation and other findings were observed in imaging results and other diagnostic studies. CONCLUSION: This review highlights the diverse presentations and diagnostic modalities used in ketamine-induced cholangiography. These patients tend to be young men with deranged liver function tests and abdominal pain, which should be taken into consideration. These patients often require a multidisciplinary approach in their management.

Van Gogh-like 2 is essential for the architectural patterning of the mammalian biliary tree.

BACKGROUND & AIMS: In the developing liver, bipotent epithelial progenitor cells undergo lineage segregation to form hepatocytes, which constitute the bulk of the liver parenchyma, and biliary epithelial cells (cholangiocytes), which comprise the bile duct (a complex tubular network that is critical for normal liver function). Notch and TGFß signalling promote the formation of a sheet of biliary epithelial cells, the ductal plate, that organises into discontinuous tubular structures. How these structures elongate and connect to form a continuous duct remains undefined. We aimed to define the mechanisms by which the ductal plate transitions from a simple sheet of epithelial cells into a complex and connected bile duct. METHODS: By combining single-cell RNA sequencing of embryonic mouse livers with genetic tools and organoid models we functionally dissected the role of planar cell polarity in duct patterning. RESULTS: We show that the planar cell polarity protein VANGL2 is expressed late in intrahepatic bile duct development and patterns the formation of cell-cell contacts between biliary cells. The patterning of these cell contacts regulates the normal polarisation of the actin cytoskeleton within biliary cells and loss of Vangl2 function results in the abnormal distribution of cortical actin remodelling, leading to the failure of bile duct formation. CONCLUSIONS: Planar cell polarity is a critical step in the post-specification sculpture of the bile duct and is essential for establishing normal tissue architecture. IMPACT AND IMPLICATIONS: Like other branched tissues, such as the lung and kidney, the bile ducts use planar cell polarity signalling to coordinate cell movements; however, how these biochemical signals are linked to ductular patterning remains unclear. Here we show that the core planar cell polarity protein VANGL2 patterns how cell-cell contacts form in the mammalian bile duct and how ductular cells transmit confluent mechanical changes along the length of a duct. This work sheds light on how biological tubes are patterned across mammalian tissues (including within the liver) and will be important in how we promote ductular growth in patients where the duct is mis-patterned or poorly formed.

Liver transplant for primary biliary tract neuroendocrine tumor in a nine-year-old girl.

BACKGROUND: Neuroendocrine tumors (NETs) are rare epithelial neoplasms that arise most commonly from the gastrointestinal tract. In pediatrics, the most common site of origin is in the appendix, with the liver being the most common site of metastasis. Neuroendocrine tumors arising from the biliary tract are extremely rare. METHODS: We describe a case of a nine-year-old girl who presented with obstructive cholestasis and was found to have multiple liver masses identified on biopsy as well-differentiated neuroendocrine tumor with an unknown primary tumor site. RESULT: The patient underwent extensive investigation to identify a primary tumor site, including endoscopy, endoscopic ultrasound, and capsule endoscopy. The patient ultimately underwent definitive management with liver transplant, and on explant was discovered to have multiple well-differentiated neuroendocrine tumors, WHO Grade 1, with extensive infiltration into the submucosa of bile duct, consistent with primary biliary tract neuroendocrine tumor. CONCLUSION: Identifying the site of the primary tumor in NETs found within the liver can be challenging. To determine if an extrahepatic primary tumor exists, workup should include endoscopy, EUS, and capsule endoscopy. Children with well-differentiated hepatic NETs, with no identifiable primary tumor, and an unresectable tumor, are considered favorable candidates for liver transplantation.

Short-term clinical outcomes of percutaneous biliary tract interventions: analysis of success and complication rates.

INTRODUCTION: Obstructive jaundice is a clinical syndrome that is commonly seen in gastroenterology. Endoscopic retrograde cholangiopancreatography (ERCP) has been recognized as a first-choice therapeutic approach, with percutaneous biliary interventions (PBIs) being a viable alternative. Recent data questions the performance and safety profile of PBIs.