Biliary Variations Research Articles

Assessment of biliary anatomy in potential living liver donors: Added value of gadoxetic acid–enhanced T1 MR Cholangiography (MRC) including utilization of controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique in comparison to T2W-MRC

ObjectivesTo assess the added value of gadoxetic-acid–enhanced T1-weighted magnetic resonance Cholangiography (T1W-MRC) including controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA)-Volumetric Interpolated Breathhold (VIBE) technique compared to T2-weighted MR Cholangiography (T2W-MRC) in depicting biliary anatomy in potential living liver donors. MethodsEighty-five potential donors including 34 men with a mean age of 35.6 years (range, 18–55 years) and 51 women with a mean age of 36.7 years (range, 23–57 years), were enrolled in this ethics-approved retrospective study. Image quality for depiction of bile ducts was evaluated by two readers in consensus in 3 separate reading sessions: 1) T2W-MRC alone, 2) T1W-MRC alone (including CAIPI-VIBE and generalized autocalibrating partially parallel acquisitions (GRAPPA)-VIBE techniques, and 3) combined T1W/T2W-MRC. Accuracy of T2W-MRC, T1W-MRC, and combined T1W/T2W-MRC for the identification/classification of the biliary variants was calculated using intraoperative cholangiogram (IOC) as the reference standard. Image quality and reader diagnostic confidence provided by CAIPI-VIBE technique was compared with GRAPPA-VIBE technique. Datasets were compared using the Wilcoxon signed-rank test. ResultsImage quality for depiction of the bile ducts was significantly superior in the combined T1W/T2W-MRC group, when compared to each of T2W-MRC and T1W-MRC groups independently (P value = 0.001–0.034). The combination of CAIPI-VIBE and GRAPPA-VIBE was superior compared to each of the sequences individually. The accuracy of T2W-MRC and T1W-MRC was 93% and 91%, respectively. T1W-MRC depicted four biliary variants better than T2W-MRC. Two variants not well seen in T2W-MRC were clearly shown on T1W-MRC. ConclusionGadoxetic-acid–enhanced T1W-MRC and conventional T2W-MRC techniques are complementary for depiction of biliary variants in potential liver donors and the combination of the two improves the results. The combination of CAIPI-VIBE and GRAPPA-VIBE techniques appear to be complementary for optimal diagnostic yield of T1W-MRC.

Intraductal Tubulopapillary Neoplasm of the Pancreas and Bile Duct: A Review.

Intraductal tubulopapillary neoplasms (ITPNs) of the pancreas and bile duct are contemporary entities. It is unclear on how to best manage patients with this diagnosis because little is known about its progression to cancer. This review provides an update on the current knowledge of ITPN of the pancreas and bile duct with an overview of clinical, radiological, histopathological, and molecular features, as well as the prognosis and management. Embase and Medline databases search were performed to identify studies that evaluated ITPN of the pancreas and bile duct. The infrequent exposure to this variant poses a diagnostic challenge. The diagnosis of ITPN is almost always made postoperatively because there are no characteristics on radiological studies to distinguish it from other cystic neoplasms of the pancreas. As ITPN has a favorable prognosis, it is crucial to establish an accurate diagnosis and differentiate it from other pancreatic and biliary variants. These neoplasms are considered to be precursor lesions to carcinomas, hence, surgery and close clinical surveillance are recommended. Further studies are essential to elucidate the natural history of ITPN, guide best treatment strategy and determine disease recurrence and survival.

Intrahepatic bile duct variation: MR cholangiography and implication in hepatobiliary surgery

BackgroundThe aim of this study was to assess the prevalence of biliary anatomical variants using 3-T MR cholangiography (MRC) with its impact in reduction of the complication of hepatobiliary surgical techniques.ResultsMRC was applied to 120 subjects (24 potential liver donors and 96 volunteers) and the right posterior hepatic duct insertion was documented, and accordingly, the biliary variants were classified based on Huang classification (Huang et al, Transplant Proc 28: 1669–1670, 1996).Biliary anatomic variants were divided based on Huang classification: Huang A1, 65.83% (n = 79); Huang A2, 11.67% (n = 14); Huang A3, 13.3% (n = 16); Huang A4, 7.5% (n = 9); and Huang A5, 1.67% (n = 2). The total frequency for A2, A3, A4, and A5 was 34.17% (n = 41). The distance between RPHD insertion and the junction of right and left hepatic ducts (L) was measured, and Huang A1 cases were then subtyped into S1 subtype (L > 1 cm) and S2 subtype (L ≤ 1 cm). We had 52 subjects with subtype S1 (43.33%) and 27 subjects with subtype S2 (22.5%).Twenty-three subjects had bile duct exploration or intraoperative cholangiograms and showed Huang type A1 in 14 (60.87%), type A2 in 3 (13.05%), and type A3 in 6 (26.08%). Twenty-two (95.65%) had the same classification in MRC and intraoperative while only one case (4.35%) was considered as A2 at MRC but the intraoperative classification was Huang A3, which was attributed to the insertion of the RPHD insertion at the distal end of the left hepatic duct.ConclusionMRC is an accurate tool for biliary tract mapping before hepatobiliary surgery to provide excellent identification of biliary variants which can reduce the incidence of biliary complications.

Main right hepatic duct entering the cystic duct: a case report

BackgroundRisk factors for bile duct injury in laparoscopic cholecystectomy include severe inflammation at Calot’s triangle and aberrant bile duct variations. Knowledge of the various biliary anomalies and early identification may therefore assist in decreasing the rate of bile duct injury.Case presentationA 65-year-old woman was admitted with right hypochondrial pain and high fever. A diagnosis of acute calculous cholecystitis was made by radiological imaging. Magnetic resonance cholangiopancreatography revealed that the confluence of the right and left hepatic duct was unclear. Intraoperatively, the procedure was converted from a laparoscopic cholecystectomy to laparotomy because of unclear anatomy of the cystic duct with severe inflammation at Calot’s triangle. Furthermore, intraoperative cholangiography from Hartmann’s pouch showed the main right hepatic duct entering the cystic duct. Subtotal cholecystectomy was performed to avoid injuring the right hepatic duct.ConclusionAlthough an aberrant hepatic duct entering the cystic duct is not uncommon, the main right hepatic duct infiltrating the cystic duct is extremely rare. Preoperative and intraoperative evaluation of the biliary duct and awareness of aberrant biliary duct variations is important in preventing bile duct injury.

High spatial resolution navigated 3D T1-weighted hepatobiliary MR cholangiography using Gd-EOB-DTPA for evaluation of biliary anatomy in living liver donors.

To determine the feasibility of high-resolution navigated three-dimensional (3D) T1-weighted hepatobiliary MR cholangiography (Nav T1 MRC) using Gd-EOB-DTPA for biliary visualization in living liver donors and to assess added value of 3D T1-weighted hepatobiliary MRCs in improving the confidence and diagnostic accuracy of biliary anatomy in complementary to T2-weighted MRCs. Twenty-nine right liver donors underwent 3D T2 MRC, 2D T2 MRC, breath-hold T1-weighted hepatobiliary MRC (BH T1 MRC), and Nav T1 MRC. Two readers independently reviewed and compared 3D/2D MRC set, added BH T1 MRC set, and added Nav T1 MRC set for biliary diagnostic accuracy and confidence. For each MRC, biliary segments visualization and image quality were scored. Both BH T1 MRC and Nav T1 MRC improved accuracy and specificity in biliary diagnosis when added to 3D/2D T2 MRC-alone set, though without statistical significance (R1, 82.8% to 93.1%; R2, 82.8% to 89.7%). The added Nav T1 MRC set showed the highest diagnostic confidence with both readers. Both readers scored Nav T1 MRC with the highest visualization scores for branching ducts and overall ducts. Combining T1-weighted hepatobiliary MRCs to 3D/2D T2 MRC set improved accuracy for biliary anatomy diagnosis; time-efficient BH T1 MRC in axial and coronal planes should be considered as a key MRC sequence complementary to T2 MRCs. Given excellent biliary visualization and superior diagnostic confidence, Nav T1 MRC in selected subjects with breath-hold difficulties and inconclusive or complex biliary variations may assist in reaching a correct biliary diagnosis.

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.

A case of congenital biliary tract dilatation (BTD) with anatomical biliary variants (ABV) identified perioperatively

A case of congenital biliary tract dilatation (BTD) with anatomical biliary variants (ABV) identified perioperatively

Clinical Implications of Biliary Confluence Pattern for Bismuth-Corlette Type IV Hilar Cholangiocarcinoma Applied to Hemihepatectomy

BackgroundSince biliary variations are commonly seen, our aims are to clarify these insidious variations and discuss their surgicopathologic implications for Bismuth-Corlette (BC) type IV hilar cholangiocarcinoma (HC) applied to hemihepatectomy. MethodsThree-dimensional images of patients with distal bile duct obstruction (n = 97) and advanced HC (n = 79) were reconstructed and analyzed retrospectively. Normal biliary confluence pattern was defined as the peripheral segment IV duct (B4) joining the common trunk of segment II (B2) and segment III (B3) ducts to form the left hepatic duct (LHD) that then joined the right hepatic duct (RHD). The lengths from left and right secondary biliary ramifications to the right side of the umbilical portion of the left portal vein (Rl-L) and the cranio-ventral side of the right portal vein (Rr-R) were measured, respectively, and compared with the resectable bile duct length in HCs. Surgicopathologic findings were compared between different BC types. ResultsThe resectable bile duct length in right hemihepatectomy for eradication of type IV tumors was significantly longer than the Rl-L length in normal biliary configuration (17.4±1.8 and 10.3±3.4 mm, respectively, p < 0.001), and type III variation (B2 joining the common trunk of B3 and B4) was the predominant configuration (53.8%). The resectable length in left hemihepatectomy for eradication of type IV tumors was comparable with the Rr-R length in RHD absent cases (15.2±2.5 and 16.4±2.6 mm, respectively, p = 0.177) but significantly longer than that in normal configuration (p < 0.001). The estimated length was 8.5 ± 2.0mm in unresectable cases. There was no significant difference between type III and IV tumors, except for the rate of nodal metastasis (29.7 and 76.0%, respectively, p < 0.001). ConclusionHemihepatectomy might be selected for curative-intent resection of BC type IV tumors considering the advantageous biliary variations, whereas anatomical trisegmentectomy is recommended for the resectable bile duct length less than 10 mm. Biliary variations might result in excessive classification of BC type IV but require validation on further study.

Non-invasive methods for diagnostics of liver fibrosis in patients with autoimmune hepatitis and autoimmune hepatitis - primary biliary cirrhosis

Aim: to evaluate the performance of non-invasive indices for the diagnosis of pronounced fibrosis and cirrhosis in patients with autoimmune hepatitis (AIH) and autoimmune hepatitis - primary biliary cirrhosis variant (AIH-PBC). Methods: Data from 70 patients with AIH and 53 patients with AIH-PBC were analyzed retrospectively. Fibrosis-4 score (FIB-4), aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio (AAR), AST to platelet ratio (APRI) and platelet count to spleen diameter ratio (PLT/SPD) were calculated based on results of blood analyses and abdominal ultrasound. Results of the histological study of the liver with the assessment of the stage of fibrosis (according to the METAVIR score) were obtained for all patients. The diagnostic accuracy of the tests was evaluated based on the area under the receiver operating characteristic curve (AUROC). Results: 51 (72.8%) of the 70 AIH patients (median age [25th - 75th interquartile range] 41 years [27-51]) had markedfibrosis (≥F2) and 28 (40%) presented with cirrhosis. In the PBC-AIHgroup (n=53; median age 50years [43.5- 57]) 42 (79.2%) and 21 (39.6%) patients had marked fibrosis (≥F2) and cirrhosis (F4), respectively. PLT/SPD was superior to other indices studied for the discrimination between mild and severe fibrosis (≥F2) as well as between severe fibrosis and cirrhosis (F4) in AIH (AUROCs: 0.840 [95% confidence interval (CI) 0.744-0.935] and 0.968 [0.934-1.000], respectively) and AIH-PBC (AUROCs: 0.752 [0.584-0.919] and 0.889 [0.800-0.979], respectively). Conclusion: The accuracy of the PLT/SPD index for diagnostics of ≥F2 is 79.1% and 76.9% and for diagnostics of F4 85.1% and 82.7% in AIH and AIH-PBC patients respectively.

The Preliminary Study on Procurement Biliary Convergence from Donors with Complicated Bile Duct Variant in Emergency Right Lobe Living Donor Liver Transplantation

The incidence of biliary complications after living donor adult liver transplantation (LDALT) is still high due to the bile duct variation and necessity reconstruction of multiple small bile ducts. The current surgical management of the biliary variants is unsatisfactory. We evaluated the role of a new surgical approach in a complicated hilar bile duct variant (Nakamura type IV and Nakamura type II) under emergent right lobe LDALT for high model for end-stage liver disease score patients. The common hepatic duct (CHD) and the left hepatic duct (LHD) of the donor were transected in a right-graft including short common trunks with right posterior and anterior bile ducts, whereas the LHD of the donor was anastomosed to the CHD and the common trunks of a right-graft bile duct and the recipient CHD was end-to-end anastomosed. Ten of 13 grafts (Nakamura types II, III, and IV) had two or more biliary orifices after right graft lobectomy; seven patients had biliary complications (53.8%). Later, the surgical innovation was carried out in five donors with variant bile duct (four Nakamura type IV and one type II), and, consequently, no biliary or other complications were observed in donors and recipients during 47-53 months of follow-up; significant differences (P<0.05) were found when two stages were compared. Our initial experience suggests that, in the urgent condition of LDALT when an alternative live donor was unavailable, a surgical innovation of cutting part of the CHD trunks including variant right hepatic ducts in a complicated donor bile duct variant may facilitate biliary reconstruction and reduce long-term biliary complications.

Biliary Tree Variants among Potential Living Liver Donors , Our Experience at King Hussein Medical Center

Biliary Tree Variants among Potential Living Liver Donors , Our Experience at King Hussein Medical Center

Cannulation of the non visualised duct: Managing biliary complications after adult-to-adult living donor liver transplantation

Background: Anatomic variations of donor bile ducts may be a significant cause of post-transplant morbidity. The aim of this study is to evaluate the impact of donor biliary variations on recipients' outcome in (AALDLT). Methods: From 2008 to 2015, 420 patients underwent AALDLT with duct-to-duct biliary reconstruction. According to donor biliary anatomy, right liver grafts (RLG) were classified into 2 groups; grafts with single right bile duct (RBD) (group1, n = 254) and grafts with multiple RBDs (group 2, n = 166). duct-to-duct biliary reconstruction was done. Type I: single right bile duct to recipient's common hepatic duct (CHD); Type II: 2 right sectorial bile ducts anastomosed to the recipient's right & left hepatic ducts; Type III: ductoplasty of the graft's sectorial bile ducts anastomosed to the recipient's CHD. mean follow-up 12 months. Results: Multiple RBDs included 2 or 3 RBD in (46.7%) and (3.3%) cases, respectively. type I in 50% of cases, type II in 21.6% and type III in 28.3%. In type 1, the incidence of biliary leakage, cholangitis & stricture was 3.3%, 13.3% & 20% respectively. In group 2 recipients, the incidence of biliary leakage, cholangitis & stricture was 8.7%, 10% & 26.7% respectively. There were no statistical significant differences in early or late biliary complications. Endoscopic management was the primary treatment modality in all patients with biliary strictures and leakage. Conclusion: Biliary complications could be managed endoscopically. RLGs with multiple biliary orifices should not be prohibited as it does not penalize recipient biliary reconstruction outcome in AALDLT.

Comparison of gadoxetic acid to gadobenate dimeglumine for assessment of biliary anatomy of potential liver donors.

To compare MRI using gadobenate dimeglumine (Gd-BOPTA) vs. gadoxetic acid disodium (Gd-EOB-DTPA) for the assessment of biliary anatomy of potential liver donors. 76 potential liver donors (39M/37F, mean 38years) who underwent 1.5T MRI using Gd-BOPTA (n=37) or Gd-EOB-DTPA (n=39) were retrospectively evaluated. T2 cholangiogram (T2 MRC) and delayed hepatobiliary phase (HBP) T1 cholangiogram (T1 MRC) (performed during HBP 20min after injection of Gd-EOB-DTPA and 1-2h after Gd-BOPTA injection) were obtained in addition to MR angiogram/venogram. Two independent observers evaluated image quality (IQ) and conspicuity scores (CS) of the biliary system. Biliary anatomy was assessed in 3 reading sessions (T2 MRC, T1 MRC, and combined T2/T1 MRC). Reference standard consisted of consensus reading of two separate observers of all image sets, clinical/surgical information and intraoperative cholangiogram when available. Datasets were compared using the Mann-Whitney U test or Chi-squared test. There was no difference in IQ for T1 MRC using either contrast agent or T2 MRC vs. T1 MRC for both observers (all p values >0.07). There was superior CS for T2 MRC vs. Gd-BOPTA T1 MRC for both observers and T2 MRC vs. Gd-EOB for one observer (p<0.001). No difference was found for biliary variant detection for T1 MRC (with either contrast agent) vs. T2 MRC. Combined T2/T1 MRC demonstrated improved sensitivity for biliary variant detection using Gd-BOPTA for both observers (p<0.004) and Gd-EOB-DTPA for one observer (p<0.001). Equivalent image quality was found for T1 MRC obtained with Gd-BOPTA or Gd-EOB-DTPA and T2 MRC. T1 MRC is equivalent to T2 MRC for detection of variant biliary anatomy, and the combination of sequences may have added value.

An Innovative Surgical Management of Complicated Bile Duct Variant in Emergency Living Donor Adult Liver Transplantation: Initial Experience

Background: The incidence of biliary complications after living donor adult liver transplantation (LDALT) is still high due to the dile duct variation and necessity reconstruction of multiple small bile ducts. The current surgical management of the biliary variants is unsatisfactory. We evaluated the role of a new surgical approach in a complicated hilar bile duct variant (Nakamura type IV and Nakamura type II) under emergent right lobe LDALT for high MELD score patients. Methods: The common hepatic duct (CHD) and the LHD of the donor were transected in a right-graft including short common trunks with right posterior and anterior bile ducts, whereas the LHD of the donor was anastomosed to the CHD and the common trunks of a right-graft bile duct and the recipient CHD was end-to-end anastomosed. Results: Ten of 13 grafts (Nakamura types II, III, and IV) had two or more biliary orifices after right graft lobectomy; seven patients had biliary complications (53.8%). Later, the surgical innovation was carried out in five donors with variant bile duct (Four Nakamura type IV and one type II), and, consequently, no biliary or other complications were observed in donors and recipients during 47-53 months of follow-up, significant differences (P<0.05) were found when two stages were compared. Conclusions: Our initial experience suggests that, in the urgent condition of LDALT when an alternative live donor was unavailable, a surgical innovation of cutting part of the CHD trunks including variant RHDs in a complicated donor bile duct variant may facilitate biliary reconstruction and reduce long-term biliary complications.

Right Hepatic Duct Drainage into Gallbladder Infundibulum: An Inevitable Bile Duct Injury during Laparoscopic Cholecystectomy

Laparoscopic cholecystectomy is gold standard for symptomatic gallstone and is world widely used for decades. With this minimally invasive approach, patients recovered from operation quicker than traditional open method. But biliary complication during this operation was not rare and had been reported. Literatures had suggested many preoperative image studies and intraoperative methods to avoid biliary complications. However, patients with biliary tree variation may have higher risk of bile duct injury during operation. Here, we present the patient with extremely rare biliary variation who encountered bile duct injury during laparoscopic cholecystectomy. The preoperative images, intraoperative findings, managements for complications, outcome and short review of the literature were recorded.

Biliary tract variations of the left liver with special reference to the left medial sectional bile duct in 500 patients

BackgroundAmong the intrahepatic bile ducts, the biliary system of the left medial sectional bile duct (B4) is known to have relatively complex patterns. MethodsThe records of 500 patients who had been diagnosed as having hepato-pancreatico-biliary disease were retrospectively studied for anatomical biliary variations of the left liver with special reference to the drainage system of B4 using magnetic resonance images. ResultsThe left hepatic duct was present in 494 patients (98.8%), whereas it was lacking in 6 patients (1.2%), and these patients exhibited the following B4 confluence patterns: B4 drained into the common hepatic duct in 2 patients (.4%), the right anterior sectional bile duct in 3 patients (.6%), and the right posterior sectional bile duct in 1 patient (.2%). The left hepatic duct was absent more frequently in patients with portal venous variations than in patients with a common branching pattern (8.2% vs .4%, P = .0011). ConclusionThe presently reported data are useful for obtaining a better understanding of the surgical anatomy of the biliary system of the left liver.

Ultrashort Common Bile Duct-A Novel Biliary Variant

Detection of variations in biliary ductal anatomy is of paramount importance as it may lead to diagnostic fallacies and ductal injury during therapeutic and surgical procedures. Authors report a unique case of ultrashort common bile duct (CBD), a novel biliary variant due to extreme low union of right and left hepatic ducts with cystic duct opening in right hepatic duct.

MRCP as a pre-operative tool in predicting variant biliary anatomy in living related liver donors

Biliary complications represent the most common cause of morbidity in living related liver donor transplantation and detailed preoperative evaluation of biliary anatomic variants is crucial for safe patient selection and improved surgical outcomes. Purpose of this study is to determine the accuracy of preoperative MRCP in predicting biliary variations when compared to intraoperative cholangiography in living related liver donors

Radiographic Features of Potential Donor Livers That Precluded Donation

The objective of our study was to catalog the anatomic features shown on preoperative CT that precluded living-donor liver donation. We retrospectively reviewed the records of 159 consecutive candidates who were evaluated for potential right or left lobe liver donation from November 2007 to January 2012 using MDCT angiography and cholangiography. For the potential donors who were excluded secondary to findings depicted on preoperative imaging, we determined which findings precluded donation. In two (1%) patients who had no prohibitive preoperative imaging findings, anatomic abnormalities were detected intraoperatively that precluded transplantation. Sixty-one (38%) candidates were excluded from liver donation on the basis of imaging findings. Of these patients, 40 (66%) had inadequate liver volume, 14 (23%) had vascular or biliary variants, five (8%) had steatosis, and two (3%) were found to have renal cell carcinoma. Arterial and biliary variants were the most common reason for exclusion based on anatomic findings. Inadequate liver volume was the most common reason for exclusion based on preoperative imaging. Arterial and biliary anatomic variants precluded both right and left lobe transplantation in a number of cases.

Repeated Introperative Cholangiography is Helpful for Donor Safety in the Procurement of Right Liver Graft with Supraportal Right Bile Duct Variants in Living-Donor Liver Transplantation

BackgroundDespite recent advances in preoperative diagnostic imaging and operative techniques, biliary variation of the donor still remains a challenge in the procurement of graft. The supraportal right bile duct (BD) variant including presentation as trifurcation is a potential trap for injuring the remnant bile duct of donor. MethodsBefore living/related-donor liver transplantation (LRLT), cholangiogram with magnetic resonance images of each donor was performed as a routine. After exploration of the donor before hilar dissection, intraoperative chloangiography (IOC) was routinely performed. Among the supraportal right bile duct variants, if the preoperative cholangiography showed a suspected trifurcation of the bile duct, we then performed 3 sessions of IOC during liver graft procurement, including prior to hilar dissection, before the division of bile ducts and after the division. We reviewed the cholangiogram and the postoperative laboratory data of a consecutive series of 25 donors of LRLT. ResultsThere was no division injury of the remnant bile duct of all of the donors. ConclusionsRepeated IOC is suggested as a routine for variants of supraportal right bile ducts especially trifurcation pattern in graft procurement to avoid the injury of donor remnant bile ducts.