Concordance of second-order portal venous and biliary tract anatomies on MDCT angiography and MDCT cholangiography

Identification and verification of communicating accessory bile duct associated with a biliary circuit by modified and dynamic intraoperative cholangiography during laparoscopic cholecystectomy

Communicating accessory bile duct (CABD) is a rare anatomical anomaly of the bile duct and forms a biliary circuit. It is difficult to identify during laparoscopic cholecystectomy (LC) without the use of intraoperative cholangiography (IOC). A modified IOC, in which tube insertion was performed through the infundibulum of the gallbladder, was evaluated dynamically. This procedure allowed us to accurately identify and verify the presence of CABD, a biliary circuit, and the short cystic duct. The short cystic duct could be separated safely without damaging the biliary circuit. Modified and dynamic IOC is recommended for identifying and verifying the presence of CABD during LC.

Anatomical variations in living donors for liver transplantation-prevalence and relationship

PURPOSE

Living donor liver transplantation (LDLT) is a widely accepted option to address the lack of a deceased liver program for transplantation. Understanding vascular and biliary anatomy and their variants is crucial for successful and safe graft harvesting. Anatomic variations are common, particularly in the right hepatic lobe. To provide evidence for screening potential liver transplant donors, the presence of vascular and biliary anatomic variations in Pakistan's preoperative assessment of transplantation donor candidates was explored.

METHODS

This retrospective cross-sectional study evaluated the hepatic artery, portal vein, hepatic vein, and biliary variations in living liver donors. The study included 400 living liver donors; data were collected from March 2019 to March 2023. We used a CT scan and MRCP to assess the anatomical variations.

RESULTS

The study examined 400 liver donors aged 18 to 53 years. Conventional arterial anatomy was the most common (65.8%), followed by replaced right hepatic artery (16%) and replaced left hepatic artery (10.8%). Conventional type 1 biliary anatomy was seen in 65.8% of cases. The dominant right hepatic vein was found in 13.3% of donors. There was a significant association between the prevalence of variant portal venous anatomy with variant biliary anatomy.

CONCLUSION

Variations of the hepatic arterial, portal venous, and biliary systems are frequent and should be carefully evaluated while selecting a suitable living donor. A strong relationship between variant portal venous and biliary anatomy was found. These findings can aid in selecting suitable candidates and improving surgical planning for liver transplantation.

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.

Deep learning reconstruction of drip-infusion cholangiography acquired with ultra-high-resolution computed tomography

PURPOSE

Deep learning reconstruction (DLR) introduces deep convolutional neural networks into the reconstruction flow. We examined the clinical applicability of drip-infusion cholangiography (DIC) acquired on an ultra-high-resolution CT (U-HRCT) scanner reconstructed with DLR in comparison to hybrid and model-based iterative reconstruction (hybrid-IR, MBIR).

METHODS

This retrospective, single-institution study included 30 patients seen between January 2018 and November 2019. A radiologist recorded the standard deviation of attenuation in the paraspinal muscle as the image noise and calculated the contrast-to-noise ratio (CNR) in the common bile duct. The overall visual image quality of the bile duct on thick-slab maximum intensity projections was assessed by two other radiologists and graded on a 5-point confidence scale ranging from 1 (not delineated) to 5 (clearly delineated). The difference among hybrid-IR, MBIR, and DLR images was compared.

RESULTS

The image noise was significantly lower on DLR than hybrid-IR and MBIR images and the CNR and the overall visual image quality of the bile duct were significantly higher on DLR than on hybrid-IR and MBIR images (all: p < 0.001).

CONCLUSION

DLR resulted in significant quantitative and qualitative improvement of DIC acquired with U-HRCT.

Living Donor Liver Transplantation: Overview, Imaging Technique, and Diagnostic Considerations

OBJECTIVE. The purpose of this article is to discuss the process of becoming a liver donor, describe the surgical methods used for transplantation, and critically review preoperative and intraoperative imaging techniques. CONCLUSION. Radiologists play a vital role in ensuring the safety of living liver donors; however, consensus guidelines do not exist for imaging protocol or reporting. Standardization would provide more consistent image quality across centers, improve communication with the transplant team, and facilitate data mining for quality assurance and research.

Evaluation of biliary anatomy in the caudate lobe using drip infusion cholangiography-computed tomography

PURPOSE

This study aimed to retrospectively evaluate the caudate branches (CBs), which are bile ducts originating from the caudate lobe (CL), using drip infusion cholangiography with computed tomography (DIC-CT).

METHODS

The confluence patterns of CBs were evaluated in 185 adult patients undergoing DIC-CT. The following bile duct features were evaluated: (a) number of depicted CBs; (b) identification of the caudate portion from which the CBs were derived; (c) identification of the confluence site of a CB; and (d) whether there was a difference in the confluence site of the CBs depending on the position of the right posterior hepatic duct (RPHD) and the portal vein (PV).

RESULTS

DIC-CT enabled detection of a total of 640 bile ducts from the CL in 185 patients, and the total number of CBs from the Spiegel lobe (SP), the paracaval portion, and the caudate process (CP) were 347 (54.2%), 112 (17.5%), and 181 (28.2%), respectively. In the SP, over 60% of CBs joined the left hepatic duct system (LHDS). The positional relationship between the RPHD and the PV was divided into a supra-portal course (n = 168) and an infra-portal course (n = 17). The number of CBs joining the LHDS was significantly different between a supra-portal course and an infra-portal course (p = 0.0484).

CONCLUSION

CBs were depicted by DIC-CT in 98.9% of the subjects, and a detailed evaluation was possible. The number of CBs joining the LHDS was associated with the position of the RPHD and the PV.

The development of an automatically produced cholangiography procedure using the reconstruction of portal-phase multidetector-row computed tomography images: preliminary experience

PURPOSE

Fusion angiography using reconstructed multidetector-row computed tomography (MDCT) images, and cholangiography using reconstructed images from MDCT with a cholangiographic agent include an anatomical gap due to the different periods of MDCT scanning. To conquer such gaps, we attempted to develop a cholangiography procedure that automatically reconstructs a cholangiogram from portal-phase MDCT images.

METHODS

The automatically produced cholangiography procedure utilized an original software program that was developed by the Graduate School of Information Science, Nagoya University. This program structured 5 candidate biliary tracts, and automatically selected one as the candidate for cholangiography. The clinical value of the automatically produced cholangiography procedure was estimated based on a comparison with manually produced cholangiography.

RESULTS

Automatically produced cholangiograms were reconstructed for 20 patients who underwent MDCT scanning before biliary drainage for distal biliary obstruction. The procedure showed the ability to extract the 5 main biliary branches and the 21 subsegmental biliary branches in 55 and 25 % of the cases, respectively. The extent of aberrant connections and aberrant extractions outside the biliary tract was acceptable. Among all of the cholangiograms, 5 were clinically applied with no correction, 8 were applied with modest improvements, and 3 produced a correct cholangiography before automatic selection.

CONCLUSIONS

Although our procedure requires further improvement based on the analysis of additional patient data, it may represent an alternative to direct cholangiography in the future.

Anatomic variations of the right hepatic duct: results and surgical implications from a cadaveric study

Purpose. Thorough understanding of biliary anatomy is required when performing surgical interventions in the hepatobiliary system. This study describes the anatomical variations of right bile ducts in terms of branching and drainage patterns, and determines their frequency. Methods. We studied 73 samples of cadaveric material, focusing on the relationship of the right anterior and posterior segmental branches, the way they form the right hepatic duct, and the main variations of their drainage pattern. Results. The anatomy of the right hepatic duct was typical in 65.75% of samples. Ectopic drainage of the right anterior duct into the common hepatic duct was found in 15.07% and triple confluence in 9.59%. Ectopic drainage of the right posterior duct into the common hepatic duct was discovered in 2.74% and ectopic drainage of the right posterior duct into the left hepatic duct in 4.11%. Ectopic drainage of the right anterior duct into the left hepatic ductal system and ectopic drainage of the right posterior duct into the cystic duct was found in 1.37%. Conclusion. The branching pattern of the right hepatic duct was atypical in 34.25% of cases. Thus, knowledge of the anatomical variations of the extrahepatic bile ducts is important in many surgical cases.

CT and MR cholangiography: advantages and pitfalls in perioperative evaluation of biliary tree

Recent developments in imaging technology have enabled CT and MR cholangiopancreatography (MRCP) to provide minimally invasive alternatives to endoscopic retrograde cholangiopancreatography for the pre- and post-operative assessment of biliary disease. This article describes anatomical variants of the biliary tree with surgical significance, followed by comparison of CT and MR cholangiographies. Drip infusion cholangiography with CT (DIC-CT) enables high-resolution three-dimensional anatomical representation of very small bile ducts (e.g. aberrant branches, the caudate branch and the cystic duct), which are potential causes of surgical complications. The disadvantages of DIC-CT include the possibility of adverse reactions to biliary contrast media and insufficient depiction of bile ducts caused by liver dysfunction or obstructive jaundice. Conventional MRCP is a standard, non-invasive method for evaluating the biliary tree. MRCP provides useful information, especially regarding the extrahepatic bile ducts and dilated intrahepatic bile ducts. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRCP may facilitate the evaluation of biliary structure and excretory function. Understanding the characteristics of each type of cholangiography is important to ensure sufficient perioperative evaluation of the biliary system.

Anatomic variations of intrahepatic bile ducts in a European series and meta-analysis of the literature

BACKGROUND

Accurate knowledge of biliary anatomy and its variants is essential to ensure successful hepatic surgery; however, data from European countries are lacking.

METHODS

Two hundred cholangiograms obtained from patients submitted to whole liver transplantation were reviewed; donors' characteristics were related to the prevalence of typical biliary anatomy and its variants. A comprehensive literature search was performed with MEDLINE and EMBASE from 1980 to 2010 to investigate whether geographical origin could be related to biliary abnormalities.

RESULTS

Typical biliary anatomy was observed in 64.5% of cases, but female donors more frequently presented an anatomic variation; typical anatomy was present in 55.0% of females and in 74.0% of males (P = 0.005). Twenty-two reports were identified by the literature search with a total of 7,559 cases, including the present series; heterogeneity was low (Q = 14.60; I2 < 5.0%) after exclusion of three outlier reports. Prevalence of typical biliary anatomy was similar in Europeans and Americans (∼60%); a slightly higher prevalence was observed in Asiatics (∼65%).

CONCLUSIONS

Anatomic variants seem to be more frequent in females, probably as a consequence of different embryologic development. Available data suggest that typical biliary anatomy can be more frequent in Asiatics, but an accurate means of classification is essential to making comparison realistic.

Ultrasound examination of the liver: Variations in the vascular anatomy

The hepatic vasculature is highly complex. The hepatic artery (a branch of the celiac tripod) and the portal vein (formed by the confluence of the splenic and superior mesenteric veins) provide a dual blood supply while venous drainage is guaranteed by the hepatic veins. There are also numerous anatomic variants that can involve one or more of the system's three components.Hepatic artery variants are the least common. Ten types have been identified, including several that are fairly frequent and others that are quite rare, and the variation generally involves the extrahepatic portion of the vessel. Portal vein variants are found in around 20% of the population. They can involve the main portal trunk or segmental branches. Variants of the hepatic veins are the most common. They involve the number and course (supernumerary veins) or the number, course, and openings (accessory veins).Knowledge of portal vein and hepatic vein variants, which are extremely common, is of prime importance for precise localization of lesions. Hepatic artery variants are equally important for surgical treatment of hepatic disease, especially liver transplantation, where it is essential for preoperative workup and postoperative follow-up of the recipient as well as for assessment of potential donors.

Reappraisal of Right Portal Segmental Ramification Based on 3-dimensional Volume Rendering of Computed Tomography During Arterial Portography

OBJECTIVE

To investigate and describe the segmental ramification patterns of the right portal vein (RPV) according to the Couinaud system.

MATERIALS AND METHODS

Between February 2004 and June 2005, 127 patients with hepatic tumors underwent computed tomography during arterial portography with a 16-slice multidetector computed tomography. The final analysis included 90 patients without RPV thrombosis or obvious vascular distortion. The ramification patterns of RPV were verified by 3-dimensional portograms using volume-rendering technique.

RESULTS

Seventy-five patients (83.3%) had bifurcation of the main portal vein, 12 (13.3%) had trifurcation, and 3 (3.3%) had the right posterior portal vein (RPPV) arising from main portal vein. A total of 5 segmental types and 3 subsegmental subgroups of RPV ramification patterns were clarified: type I, the classic ramification pattern with right anterior portal vein (RAPV) branching to S8/S5 and RPPV branching to S7/S6 (63; 70%); II, two separate segmental branches to S7 and S6 without a definite main stem of RPPV (18; 20%); III, "whisk-like" ramification pattern of RPV (2; 2.2%); IV, RAPV branching to S8 alone and RPPV to S5, S6, and S7, consecutively (5; 5.6%); and V, RPV first branching to S8/S5 and then to S7/S6 after a common path (2; 2.2%); subgroup a with dorsocranially directed branches arising from P8 and supplying S8 posterior to the right hepatic vein (28; 31.1%); subgroup b with RPPV branching to the dorsal part of S5 (11; 12.2%); and subgroup a + b, combination of the aforementioned 2 subgroups (45; 50%). In most patients, RAPV had dorsocranially directed branches posterior to the right hepatic vein (73; 81.1%), and RPPV gave off branches to the dorsal part of S5 (56; 62.2%).

CONCLUSIONS

Recognition of these ramification patterns could be helpful for more accurate anatomical resection of right hemiliver and preoperative planning, although some variants are present.

Ultrasound examination of the liver: Normal vascular anatomy

Various treatments for liver diseases, including liver transplant (particularly partial liver resection from a living donor), treatment of liver tumors, and TIPS, require detailed knowledge of the complex vascular anatomy of the liver. The hepatic artery and portal vein provide the organ with a double blood supply whereas venous drainage is furnished by the hepatic veins.Multislice computed tomography and magnetic resonance imaging provide undeniably excellent information on these structures. On ultrasound, the inferior vena cava, the openings of the hepatic veins, and the main branch of the portal vein can always be visualized, but intrasegmental vessels (portal, arterial, accessory hepatic venous branches) can be only partially depicted and in some cases not at all.In spite of its difficulty and limitations, hepatic sonography is frequently unavoidable, particularly in critically ill patients, and the results are essential for defining diagnostic and therapeutic strategies. For this reason, a thorough knowledge of the sonographic features of hepatic vascular anatomy is indispensable.

Predicting Biliary Complications in Right Lobe Liver Transplant Recipients according to Distance between Donor's Bile Duct and Corresponding Hepatic Artery

PURPOSE

To retrospectively determine whether biliary complications in recipients of living-donor right lobe liver grafts can be predicted at pretransplantation donor computed tomography (CT).

MATERIALS AND METHODS

The human research committee approved this study. The requirement for informed consent was waived. Multi-detector row CT cholangiography and CT angiography were performed in 44 consecutive right lobe liver donors (25 men, 19 women; mean age, 37 years). When CT cholangiography in the donor demonstrated the right biliary anatomy (conventional or variant), the shortest distance between the right main (or second-order) hepatic artery and the corresponding right main (or second-order) bile duct was measured and compared with posttransplantation biliary complications in the transplant recipient by using generalized estimating equations.

RESULTS

In 22 transplant recipients with one right main duct-to-common duct anastomosis (ie, conventional donor anatomy), the distance between the donor's right main bile duct and hepatic artery generally was small (mean distance, 3.8 mm; range, 1-14 mm) and unrelated (P=.46) to biliary complications (n=6). In 22 recipients who required two second-order right duct anastomoses (ie, with variant donor anatomy), the distance between the donor's second-order duct and corresponding hepatic artery was more variable (mean distance, 6.6 mm; range, 1-32.5 mm), and biliary complications were significantly more common when this distance was 10 mm or greater (in eight of 13 ducts with conventional anatomy and four of 31 ducts with variant anatomy, P<.05).

CONCLUSION

Right lobe liver graft recipients who have variant right biliary anatomy and a second-order bile duct 10 mm or farther from the corresponding hepatic artery are at high risk for biliary complications, possibly because of a predisposition to ischemic injury.

Liver and Biliary System: Evaluation by Multidetector CT

CT commonly is indicated for the evaluation of suspected hepatic and biliary pathology. The recent introduction of multidetector CT (MDCT) provides unique capabilities that are valuable especially in hepatic volume acquisitions, combining short scan times, narrow collimation, and the ability to obtain multiphase data. These features result in improved lesion detection and characterization. Concomitant advances in computer software programs have made three-dimensional applications practical for a range of hepatic image analyses and displays. This article discusses the specific areas of hepatic and biliary pathology where MDCT has a significant diagnostic impact.