Magnetic resonance cholangiopancreatography evaluation of intrahepatic bile duct variations with updated classification

Association between anatomic variations of extrahepatic and intrahepatic bile ducts: Do look up!

Biliary anatomic variations are usually asymptomatic, but they may cause problems in diagnostic investigations and interventional and surgical procedures, increasing both their technical difficulty and their postoperative complication rates. The aim of the present study was to evaluate the prevalence of anatomic variations in the intrahepatic biliary ducts (IHBD) in relation to demographical and clinical characteristics in a large study population requiring magnetic resonance cholangiopancreatography (MRCP) for various clinical conditions. The possible association between IHBD and extrahepatic biliary ducts (EHBD) variants was then explored. From January 2017 to May 2019, 1004 patients underwent MRCP. Demographical and clinical data were collected. IHBD and EHBD anatomy were recorded and the EHBD anatomy was classified using both qualitative and quantitative classifications. The presence of a type 3 EHBD variant (an abnormal proximal cystic duct [CD] insertion) in both qualitative and quantitative classifications and an intrapancreatic CD were associated with the presence of IHBD variants at univariate analysis (p = 0.008, p = 0.019, and p = 0.001, respectively). The presence of a posterior or medial insertion of the CD into the EHBD was a strong predictive factor of the presence of IHBD variants both at uni- and multivariate analysis (p = 0.002 and p = 0.003 for posterior insertion and p = 0.002 and p = 0.002 for medial insertion, respectively). The presence of gallstones on MRCP resulted in a strong predictor of the presence of an anatomical variant of the IHBD both at uni- and multivariate analysis (p = 0.027 and p = 0.046, respectively). In conclusion, the presence of a type 3 variant of the EHBD, an intrapancreatic CD and, especially, a posterior/medial CD insertion into the EHBD represent predictive factors of the concomitant presence of IHBD variants, thus radiologists must be vigilant when encountering these EHBD configurations and always remember to "look up" at the IHBD. Finally, the presence of an IHBD variant is a strong predictive factor of gallstones.

Our Experience in Tracking the Tract: Normal Biliary Anatomy and Variants on Magnetic Resonance Cholangiopancreatography in Living Donor Liver Transplantation

Objective Biliary anatomy is of paramount importance for hepatobiliary pancreatic surgeons for operative planning. Preoperative assessment with magnetic resonance cholangiopancreatography (MRCP) to evaluate the biliary anatomy plays a vital role, especially for prospective liver donors in living donor liver transplantation (LDLT). Our objective was to evaluate the diagnostic accuracy of MRCP in assessing the anatomical variations of the biliary system and the frequency of biliary variation in the donors of LDLT. Materials and Methods Sixty-five donors of living donor liver transplantation in the age range of 20 to 51 years were studied retrospectively to evaluate the anatomical variations of the biliary tree. As a part of the pre-transplantation donor workup, MRI with MRCP was performed in a 1.5T machine for all these candidates. MRCP source data sets were processed with maximum intensity projections, surface shading, and multi-planar reconstructions. Images were reviewed by two radiologists, and the classification system of Huang et al. was utilized to evaluate the biliary anatomy. The results were compared with the intraoperative cholangiogram, considered the gold standard. Results We identified standard biliary anatomy in 34 candidates (52.3%), and variant biliary anatomy was observed in 31 candidates (47.7%) on MRCP. An intraoperative cholangiogram showed standard anatomy in 36 candidates (55.4%) and biliary variation in 29 candidates (44.6%). Our study showed a sensitivity of 100% and a specificity of 94.5% for identifying biliary variant anatomy on MRCP in comparison with the gold standard intraoperative cholangiogram. The accuracy of MRCP in detecting the variant biliary anatomy in our study was 96.9%. The most common biliary variation was the right posterior sectoral duct draining into the left hepatic duct, Huang type A3. Conclusion The frequency of biliary variations is high in potential liver donors. MRCP is sensitive and highly accurate in identifying the biliary variations of surgical significance.

Anatomic variations of the intra-hepatic biliary tree in the Caribbean: A systematic review

BACKGROUND

In the classic descriptions of the human liver, the common hepatic duct forms at the confluence of left and right hepatic ducts. Many authors have documented variations in the intra-hepatic ductal system, but to the best of our knowledge there has been no report on bile duct variations in Caribbean populations.

AIM

To evaluate the variations in bile duct anatomy using magnetic resonance cholangiography (MRC) in unselected patients at a major hepatobiliary referral centre in the Eastern Caribbean. Knowledge of the intra-hepatic biliary anatomy is important to optimize service delivery for any physician treating liver and biliary disorders.

METHODS

This study was carried out at a tertiary referral hospital for hepatobiliary diseases in the Eastern Caribbean. We retrospectively evaluated magnetic resonance cholangiograms in 152 consecutive patients at this facility over a two-year period from April 1, 2017 to March 31, 2019. Two consultant radiologists experienced in MRC interpretation reviewed all scans and described biliary anatomy according to the Huang’s classification. A systematic review of published studies was performed and relevant data were extracted in order to calculate the global prevalence of each biliary variant. The variants in our population were compared to the global population.

RESULTS

There were 152 MRCs evaluated in this study in 86 males and 66 females. There were 109 (71.7%) persons with “classic” biliary anatomy (type A1) and variants were present in 43 (28.3%) persons. There was no statistical relationship between the presence of anatomic variants and gender or ethnicity. We encountered the following variants: 29 (19.1%) type A2, 7 (4.6%) type A3, 6 (3.95%) type A4, 0 type A5 and a single variant (quadrification) that did not fit the classification system. Compared to the global prevalence, our population had a significantly greater occurrence of A1 anatomy (71.7% vs 62.6%; P = 0.0227) and A2 trifurcations (19.1% vs 11.5%; P = 0.0069), but a significantly lower incidence of A3 variants (4.61% vs 11.5%; P = 0.0047).

CONCLUSION

There are significant differences in intra-hepatic biliary anatomy in this unselected Eastern Caribbean population compared to global statistics. Specifically, persons of Caribbean descent have a greater incidence of Huang A2 trifurcations and a lower incidence of Huang A3 variants.

Comprehensive classification of anatomical variants of the main biliary ducts

This systematic review provides the most comprehensive overview of intrahepatic biliary anatomical variants to date. Additionally, it proposes a clinically focused, prevalence-based classification system based on meta-analysis of a large pooled dataset whilst incorporating the merits of previous classification systems.

Prevalence of Different Hepatobiliary Tree Variants on Magnetic Resonance Cholangiopancreatography in Patients Visiting a Tertiary Care Teaching Hospital in Karachi

Introduction

Hepatobiliary tree variant anatomy is crucial to understand the preoperative planning of hepatobiliary surgeries. Although the presence of variant anatomy is not an absolute contraindication for liver transplantation, inadvertent mapping can lead to postoperative biliary complications. These variants are also important to be recognized in various hepatobiliary surgeries and interventional procedures. Magnetic resonance cholangiopancreatography (MRCP) is an excellent non-invasive imaging tool that can identify biliary anatomy. The purpose of the current study is focused on determining anatomical variants of the biliary tree on MRCP in our population visiting a teaching hospital in Karachi.

Methods

This cross-sectional study was conducted on patients referred to Dr. Ziauddin Hospital for MRCP. MRCP was performed on MAGNETOM Avanto, SIEMENS, Belgium, Germany. Images were analyzed on a workstation by two radiologists and a postgraduate trainee. A senior radiologist reviewed equivocal cases. SPSS 22.0 (SPSS Inc., Chicago, IL) was used for statistical analysis. Chi-square test was used to see the link between anatomical variants of biliary tree and gender. P-value of ≤0.05 was considered as statistically significant.

Results

We recruited 369 patients undergoing MRCP consecutively for our study. Out of 369, 342 patients were eligible for analysis (139 males and 203 females). Standard anatomy was found to be prevalent in 65.8%. Type 3 was the leading variant. A statistically significant difference was recorded for the type 2 anatomic variant which was more frequent in males than females (p-value <0.001), while types 1, 3, and 4 anatomic variants were found to be more in females than males but this difference was not statistically significant. Few other variants were also recorded.

Conclusion

This study is robust evidence regarding biliary variants in Pakistan. It is important to consider these variants in our region, owing to an increased trend of liver transplants and other hepatobiliary procedures.

Effectiveness of near-infrared fluorescent cholangiography in the identification of cystic duct-common hepatic duct anatomy in comparison to magnetic resonance cholangio-pancreatography: a preliminary study

INTRODUCTION

Bile duct injury represents the most serious complication of LC, with an incidence of 0.3-0.7% resulting in a significant impact on quality-of-life, overall survival, and frequent medico-legal litigations. Near-infrared fluorescent cholangiography (NIRF-C) represents a novel intra-operative imaging technique that allows a real-time enhanced visualization of the extrahepatic biliary tree by fluorescence. The role of routine use of pre-operative magnetic resonance cholangio-pancreatography (MRCP) to better clarify the biliary anatomy before laparoscopic cholecystectomy is still a matter of debate. The primary aim of this study was to evaluate the effectiveness of NIRF-C in the detection of cystic duct-common hepatic duct anatomy intra-operatively in comparison with pre-operative MRCP.

METHODS

Data from 26 consecutive patients with symptomatic cholelithiasis or chronic cholecystitis, who underwent elective laparoscopic cholecystectomy with intra-operative fluorescent cholangiography and pre-operative MRCP examination between January 2018 and May 2018, were analyzed. Three selected features of the cystic duct-common hepatic duct anatomy were identified and analyzed by the two different imaging methods: insertion of cystic duct, cystic duct-common hepatic duct junction, and cystic duct course.

RESULTS

Fluorescent cholangiography was performed successfully in all twenty-six patients undergoing elective laparoscopic cholecystectomy. The visualization of cystic duct was reported in 23 out of 26 cases, showing an overall diagnostic accuracy of 86.9%. The level of insertion, course, and wall implantation of cystic duct were achieved by NIRF-C with diagnostic accuracy values of 65.2%, 78.3%, and 91.3%, respectively in comparison with MRCP data. No bile duct injuries were reported.

CONCLUSION

Fluorescent cholangiography can be considered a useful imaging diagnostic tool comparable to MRCP for detailed intra-operative visualization of the cystic duct-common hepatic duct anatomy during elective laparoscopic cholecystectomies.

Evaluating the origin of vascular structures in ectopic kidneys with multidetector computed tomography

PURPOSE

The purpose of this study is to investigate the origin of the vascular structures in ectopic kidneys with multidetector computed tomography (CT).

METHODS

The abdominal CT images of 96 cases with 106 ectopic kidneys were retrospectively reviewed. The ectopic kidney location, type of ectopia, and the origins of renal arteries and veins of the ectopic kidneys were evaluated. The origins of the renal arteries and veins were classified as suprarenal aorta/inferior vena cava (IVC), normal origin, infrarenal aorta/IVC, aortic/IVC bifurcation, common iliac artery/vein, iliac bifurcation, internal iliac artery/vein, and external iliac artery/vein. Finally, the ectopic kidneys were classified according to the most common combinations of artery and vein origins.

RESULTS

The renal artery originated from the suprarenal aorta in 1 case, normal origin in 13 cases, the infrarenal aorta in 36 cases, aortic bifurcation in 50 cases, the common iliac artery in 17 cases, and the iliac artery bifurcation in 2 cases. The renal vein was of normal origin in 19 cases, originated from the infrarenal IVC in 44 cases, IVC bifurcation in 36 cases, the common iliac vein in 23 cases, the internal iliac vein in 1 case, and the external iliac vein in 1 case. We classified the artery and vein origins of the ectopic kidneys into 7 most common types and other less common types. A significant correlation was found between the level of the ectopic kidneys and the origin of the arteries and veins (P < 0.001).

CONCLUSIONS

Our study shows that the majority of ectopic kidneys have various origins of arterial and venous supply. We described the most common vascular origins of ectopic kidneys. Prior knowledge of these vascular variations may have important implications in preventing iatrogenic hemorrhage during surgery of patients with ectopic kidney.

Variations in the vascular and biliary structures of the liver: a comprehensive anatomical study

PURPOSE

Vascular structures of the liver and the bile ducts are crucial during liver transplantation or liver resection surgery. Here, we report on variations in the vascular structures and bile ducts of 200 patients.

MATERIALS AND METHODS

We reviewed magnetic resonance cholangiopancreatographic and multiple-detector computed tomographic data.

RESULTS

Michels type 1 was detected in 54% of the patients. The other most common variations were, respectively, Michels type 5 (13%) and type 2 (11%). Unclassified variations were defined as Michels type 11; 5% of patients were in this group. Type 1 variations in the hepatic portal vein were detected in 76% of our study group. Other common variations were type 2 (9%) and type 3 (8.5%). The left and intermediate hepatic veins united to become a single vein and then joined the inferior vena cava in 64% of the patients. The right, intermediate, and left hepatic veins joined the inferior vena cava separately in 36% of the patients. Type A, which represents the classic anatomy of the bile duct, was observed in 51.5% of our patients. Type C1 and type B were detected in 15% and 12% of patients, respectively.

CONCLUSIONS

We describe vascular and biliary variations in the livers of our patients.

Frequency of bile duct confluence variations in subjects with pancreas divisum: an analysis of MRCP findings

PURPOSE

We aimed to evaluate the frequency of bile duct branching pattern variations at the hepatic confluence in patients with pancreas divisum (PD).

METHODS

A search was performed through the hospital database using the keyword "pancreas divisum" to identify patients. The magnetic resonance cholangiopancreatography (MRCP) images of 137 patients who were diagnosed with PD between August 2011 and November 2016 were retrospectively analyzed for the presence of bile duct variations. A control group of 137 patients without PD was established among patients investigated during the same period. Variations of the biliary tract were grouped into seven types according to the McSweeney et al. classification.

RESULTS

Biliary tract variations were detected in 103 of a total of 274 patients. Fifty-eight PD patients (42.3%) and 45 control patients (32.8%) had bile duct variation at the hepatic confluence level. The patients with PD were more likely to have biliary tract variation compared with the control group; however, it was not statistically significant (P = 0.105). The most common variation in PD patients was type 3a variation (16.8%).

CONCLUSION

MRCP studies showed atypical bile duct confluence pattern in nearly half of both PD patients and controls. There was no statistically significant difference in the frequency of anatomic variations at bile duct confluence in patients with PD versus those without PD. Derivation of these structures from different outpouchings in early embryological life may explain this insignificant difference.