3-T MRI of the biliary tract variations

The anatomy of the cystic duct and its association with cholelithiasis: MR Cholangiopancreatographic study

INTRODUCTION

The aims of this article are to detail the anatomy of the cystic duct in patients with and without gallstones as it relates to maneuvering of the duct during endoscopic transpapillary gallbladder cannulation, and to elucidate its role in the dynamics of bile flow during gallbladder contraction.

MATERIAL AND METHODS

One hundred MRCPs were retrieved from the prospectively maintained radiology data system to assess the configuration of the cystic duct and its confluence vis-a-vis the main biliary duct.

RESULTS

The configuration of the cystic duct was broadly classified into four types: Angular (44%), Linear (40%), Spiral (11%) and Complex (5%). The level of emergence of the cystic duct from the bile duct was proximal in 29%, middle in 49% and distal in 20%. Its direction from the bile duct was to the right and angled upward in 69%, right and angled downward in 15%, left and angled upward in 13%, and left and angled downward in 1%. Its orifice was on the lateral surface of the bile duct in 50%, posterior in 19%, anterior in 15% and medial in 14%. In two cases, the cystic duct opened directly into the duodenum. Tortuous cystic ducts and non-lateral unions with the bile duct were significantly more prevalent in gallstone cases than the non-gallstone group (p=0.02).

CONCLUSIONS

The present study details the spatial anatomy of the cystic duct vis a vis the main biliary duct. This has not been well investigated to date but has become increasingly relevant with the advent of recent gallbladder interventions.

Anatomic Variations of the Cystic Duct in Magnetic Resonance Cholangiopancreatography in Shiraz: A Cross-Sectional Study

BACKGROUND

Anatomic variations of the cystic duct (CD) are commonly encountered. Being aware of these variants will reduce complications subsequent to surgical, endoscopic, or percutaneous procedures. Magnetic resonance cholangiopancreatography (MRCP) is the least invasive and the most reliable modality for biliary anatomy surveys. This study aimed to determine the prevalence of cystic duct variations in the Iranian population.

METHODS

In this retrospective cross-sectional study, MRCP images of 350 patients referred to Shiraz Faraparto Medical Imaging and Interventional Radiology Center from October 2017 to October 2018 were reviewed. The CD course and insertion site to the extrahepatic bile duct (EHBD) was determined and documented in 290 cases. Descriptive statistics and Chi square test were applied for data analysis via SPSS software.

RESULTS

About 77% of cases revealed the classic right lateral insertion to the middle third of EHBD. The insertion of CD to the upper third and the right hepatic duct was 10%, and the insertion to the medial aspect of the middle third of EHBD from anterior or posterior was noted to be about 7.6%. From 2.8% of insertions to the lower third, 1% demonstrated parallel course, and finally, 0.3% of cases presented short CD.

CONCLUSION

CD variations are relatively common, and MRCP mapping prior to the hepatobiliary interventions could prevent unexpected consequences.

Anatomical variations of cystic duct insertion and their relationship with choledocholithiasis: an MRCP study

Background

The frequency of insertion variations of cystic duct (CD) is inconsistent between studies caused to some extent by the way they give the relative frequency of the variations. Moreover, certain insertion variations have been reported to be associated with choledocholithiasis. This study aimed to assess the frequency of CD insertion variations with a comprehensive way of classification in an unselected population in whom MRCP was performed. Moreover, the relationship between the types of variant insertions and choledocholithiasis using MRCP was also assessed. Patients undergoing magnetic resonance cholangiopancreatography (MRCP) were reviewed retrospectively by two radiologists who were blinded to the clinical data. The normal insertion was defined as the union through middle one third of the lateral border of the extrahepatic bile duct. The transverse site (lateral, medial, anterior, and posterior) and the craniocaudal level (high, mid and low) of insertions and their intersections were assessed using axial and coronal slices, respectively. In addition, the frequencies of the CD insertion variations were compared between choledocholithiasis and control (no-choledocholithiasis) groups.

Results

A total of 307 patients (124 with choledocholithiasis and 183 controls) were analyzed. A true variant insertion was found in 149 (48.5%) cases. The insertion variations were less frequent in the choledocholithiasis group [50 (40.3%) vs. 99 (54.1%), respectively, p = 0.018]. The frequencies of craniocaudal level of insertion differed significantly between groups (p = 0.014) that was driven by a lower rate of low medial insertion (1.6% vs. 9.8%, respectively) in the choledocholithiasis group. The frequencies of transverse site of insertion were similar between groups (p = 0.314). The low medial insertion was 80.7% less likely associated with choledocholithiasis even after adjustment for age (Odds ratio: 0.193, 95% Confidence interval: 0.039–0.954, p = 0.044). The interreader agreement for insertion assessment was good (Cohen’s Kappa: 0.748, p < 0.001).

Conclusions

The prevalence of CD insertion variations in an unselected population undergoing MRCP is quite high and a mid-posterior insertion is the most common variant type. Insertion variations of CD, the low medial insertion in particular, are less common in patients with choledocholithiasis than controls.

Three-dimensional visualization technique compared with magnetic resonance cholangiopancreatography for evaluation of anatomic variants of pediatric congenital choledochal cysts

OBJECTIVE

The aim of this study was to compare the application of a three-dimensional (3D) visualization technique and magnetic resonance cholangiopancreatography (MRCP) for diagnosis of pediatric congenital choledochal cysts.

METHODS

Thin slices of coronal heavily T2-weighted pulse sequences of MRI pertaining to 35 patients were retrospectively used to reconstruct 3D models. Diagnoses and variants of the biliary system were evaluated based on the 3D models and MRCP imaging. The quality of delineation of the biliary duct system and the Todani classification were evaluated. Wilcoxon and Chi-squared tests were used for statistical analysis.

RESULTS

Two cases that were diagnosed as type II congenital choledochal cysts using the 3D model were diagnosed as type I using MRCP imaging. Significant differences were observed between the two modalities with respect to the delineation of the right anterior bile duct, right posterior bile duct, and left hepatic duct. The excellent and good rates obtained with the 3D model (65.7%) were much better than that obtained with MRCP (37.1%) imaging. Two cases with accessory hepatic ducts (5.7%), one case with an accessory pancreatic duct (2.8%), and two cases with biliary strictures at the hepatic hilum (5.7%) were detected using the 3D models. In contrast, only one case with an accessory hepatic duct and one case with a biliary stricture at the hepatic hilum were detected using MRCP.

CONCLUSION

The 3D visualization technique facilitated more precise morphological evaluation of congenital choledochal cysts and provided comprehensive spatial anatomic information for diagnosis.

Risk of Gallstone Formation in Aberrant Extrahepatic Biliary Tract Anatomy: A Review of Literature

The age-long mnemonic of '5Fs' (fat, female, fertile, forty, and fair) has traditionally been used in medical school instructions to describe the risk factors for gallstone disease. However, evidence suggests that aberrant extrahepatic biliary tract (EHBT) anatomy may contribute significantly to the risk of gallstone disease. This review explores the anatomy and embryological bases of EHBT variations as well as the prevalence of these variations. Also, we discuss the risk factors for gallstone formation in the relationship between gallstone disease and aberrant EHBT anatomy.

A novel classification of aberrant right hepatic ducts ensures a critical view of safety in laparoscopic cholecystectomy

BACKGROUND

Based on the spatial relationship of an aberrant right hepatic duct (ARHD) with the cystic duct and gallbladder neck, we propose a practical classification to evaluate the specific form predisposing to injury in laparoscopic cholecystectomy (LC).

METHODS

We retrospectively investigated the preoperative images (mostly magnetic resonance cholangiopancreatography) and clinical outcomes of 721 consecutive patients who underwent LC at our institute from 2015 to 2018. We defined the high-risk ARHD as follows: Type A: communicating with the cystic duct and Type B: running along the gallbladder neck or adjacent to the infundibulum (the minimal distance from the ARHD < 5 mm), regardless of the confluence pattern in the biliary tree. Other ARHDs were considered to be of low risk.

RESULTS

A high-risk ARHD was identified in 16 cases (2.2%): four (0.6%) with Type A anatomy and 12 (1.7%) with Type B. The remaining ARHD cases (n = 34, 4.7%) were categorized as low risk. There were no significant differences in the operative outcomes (operative time, blood loss, hospital stay) between the high- and low- risk groups. Subtotal cholecystectomy was applied in four cases (25%) in the high-risk group, a significantly higher percentage than the low-risk group (n = 1, 2.9%). In all patients with high-risk ARHD, LC was completed safely without bile duct injury or conversion to laparotomy.

CONCLUSIONS

Our simple classification of high-risk ARHD can highlight the variants located close to the dissecting site to achieve a critical view of safety and may contribute to avoiding inadvertent damage of an ARHD in LC.

High insertion of cystic duct at the gallbladder fundus: An undescribed anomaly!

The anatomy of the biliary tree is complex, and its variations of both intra- and extra-hepatic bile ducts can be found in approximately 30% of the general population. These variations are not picked up on routine pre-operative investigations of patients planned for a laparoscopic cholecystectomy (LC) and often present as an unusual ‘surprise’ and a challenge that can make dissection in the Calot's triangle difficult leading to iatrogenic injury. We present a case of a 53-year-old female with an undescribed anomaly encountered during an LC. There was a high insertion of the cystic duct into the fundus of the gallbladder. No such anomaly has been described in literature till date.

A rare anatomical variation of the biliary tree

A 31-year-old woman was admitted to our department in order to undergo a laparoscopic cholecystectomy. The operation was converted to open due to cholorrhea during the dissection in the hepatocystic triangle. The cholorrhea came from a transected bile duct, which was 2 mm in diameter, came out of the hepatoduodenal ligament, ran along the common hepatic duct and drained into the cystic duct, in proximity to the neck of the gallbladder. The gallbladder was removed and an intraoperative cholangiography revealed that the aberrant bile duct was originated from the right posterior sectoral duct (RPSD). The RPSD continued its typical course up to its confluence with the right anterior sectoral duct and the formation of the right hepatic duct. This is a rare type of aberrant bile duct, which is added to the long catalogue of the anatomical variations of the biliary tree.

Anatomic variations of the pancreatic duct and their relevance with the Cambridge classification system: MRCP findings of 1158 consecutive patients

BACKGROUND

The study was conducted to evaluate the frequencies of the anatomic variations and the gender distributions of these variations of the pancreatic duct and their relevance with the Cambridge classification system as morphological sign of chronic pancreatitis using magnetic resonance cholangiopancreatography (MRCP).

PATIENTS AND METHODS

We retrospectively reviewed 1312 consecutive patients who referred to our department for MRCP between January 2013 and August 2015. We excluded 154 patients from the study because of less than optimal results due to imaging limitations or a history of surgery on pancreas. Finally a total of 1158 patients were included in the study.

RESULTS

Among the 1158 patients included in the study, 54 (4.6%) patients showed pancreas divisum, 13 patients (1.2%) were defined as ansa pancreatica. When we evaluated the course of the pancreatic duct, we found the prevalence 62.5% for descending, 30% for sigmoid, 5.5% for vertical and 2% for loop. The most commonly observed pancreatic duct configuration was Type 3 in 528 patients (45.6%) where 521 patients (45%) had Type 1 configuration.

CONCLUSIONS

Vertical course (p = 0.004) and Type 2 (p = 0.03) configuration of pancreatic duct were more frequent in females than males. There were no statistically significant differences between the gender for the other pancreatic duct variations such as pancreas divisium, ansa pancreatica and course types other than vertical course (p > 0.05 for all). Variants of pancreas divisum and normal pancreatic duct variants were not associated with morphologic findings of chronic pancreatitis by using the Cambridge classification system. The ansa pancreatica is a rare type of anatomical variation of the pancreatic duct, which might be considered as a predisposing factor to the onset of idiopathic pancreatitis.

Anatomical Variations of Cystic Ducts in Magnetic Resonance Cholangiopancreatography and Clinical Implications

Background. Anatomical variations of cystic duct (CD) are frequently unrecognized. It is important to be aware of these variations prior to any surgical, percutaneous, or endoscopic intervention procedures. Objectives. The purpose of our study was to demonstrate the imaging features of CD and its variants using magnetic resonance cholangiopancreatography (MRCP) and document their prevalence in our population. Materials and Methods. This study included 198 patients who underwent MRCP due to different indications. Images were evaluated in picture archiving communication system (PACS) and variations of CD were documented. Results. Normal lateral insertion of CD at middle third of common hepatic duct was seen in 51% of cases. Medial insertion was seen in 16% of cases, of which 4% were low medial insertions. Low insertion of CD was noted in 9% of cases. Parallel course of CD was present in 7.5% of cases. High insertion was noted in 6% and short CD in 1% of cases. In 1 case, CD was draining into right hepatic duct. Congenital cystic dilation of CD was noted in one case with evidence of type IV choledochal cyst. Conclusion. Cystic duct variations are common and MRCP is an optimal imaging modality for demonstration of cystic duct anatomy.

Morphologic factors of biliary trees are associated with gallstone-related biliary events

AIM: To determine the risk factors for gallstone-related biliary events.

METHODS: This retrospective cohort study evaluated magnetic resonance cholangiopancreatography images from 141 symptomatic and 39 asymptomatic gallstone patients who presented at a single tertiary hospital between January 2005 and December 2012.

RESULTS: Logistic regression analysis showed significant differences between symptomatic and asymptomatic patients with gallstones in relation to the number of gallstones, the angle between the long axis of the gallbladder and the cystic duct, and the cystic duct diameter. Multivariate analysis showed that the number of gallstones (OR = 1.27, 95%CI: 1.03-1.57; P = 0.026), the angle between the long axis of the gallbladder and the cystic duct (OR = 1.02, 95%CI: 1.00-1.03; P = 0.015), and the diameter of the cystic duct (OR = 0.819, 95%CI: 0.69-0.97; P = 0.018) were significantly associated with biliary events. The incidence of biliary events was significantly elevated in patients who had the presence of more than two gallstones, an angle of > 92° between the gallbladder and the cystic duct, and a cystic duct diameter < 6 mm.

CONCLUSION: These findings will help guide the treatment of patients with asymptomatic gallstones. Clinicians should closely monitor patients with asymptomatic gallstones who exhibit these characteristics.