Intrahepatic portal vein branches studied by percutaneous transhepatic portography

International multidisciplinary consensus recommendations on clinical application of three-dimensional visualization in precision surgery for pediatric liver tumors

BACKGROUND

Pediatric liver tumors are predominantly primary malignant tumors, and complete tumor resection with sufficient preservation of liver tissue is crucial for improving prognosis. However, due to the delicate anatomical structure of the pediatric liver and the relatively large size of the tumors, especially in difficult cases, the surgical challenges are substantial. While precision liver surgery are widely applied in clinical practice, pediatric cases require more customized approaches. The application of three-dimensional (3D) visualization technology is crucial for enhancing surgical accuracy, allowing for precise preoperative planning and intraoperative guidance.

METHODS

This consensus was collaboratively developed by 36 experts from eight countries, using the Glaser's state-of-the-art method to review and refine the draft.

RESULTS

The final consensus resulted in 15 international multidisciplinary consensus recommendations on clinical application of 3D visualization in precision surgery for pediatric liver tumors.

CONCLUSION

This consensus will standardize the application of 3D visualization technology in precision surgery for pediatric liver tumors to improve outcomes and reduce risks.

Comprehensive evaluation of the ramification patterns of hepatic vascular anatomy based on three-dimensional visualization technology

The liver segmentation method proposed by Couinaud is widely accepted by surgeons because of its convenience and practicality. However, this conventional eight-segment classification does not reflect realistic details of the liver and thus requires further adjustments to promote improvements in surgical strategies. This study aimed to explore the ramification patterns of the hepatic vasculature comprehensively. A total of 197 eligible patients meeting the study criteria were enrolled for three-dimensional reconstruction analysis. In the left hemiliver, the portal vein bifurcated into P2 and umbilical portion (UP) in 172 (98.3%) patients. The P4b of 103 patients (103/172, 59.9%) whose P4b branched from the right horn of the left portal vein (LPV) diverged from the main trunk of the UP. In the right paramedian sector (RPMS), the entire portal trunk directly bifurcates into P8vent and P8dor. Simple branching of P5 off the trunk of the RPMS was observed in 78 patients (78/130, 60%). The anterior fissure vein (AFV) was identified in 86 (86/148, 58.1%) patients. V8d entered the right hepatic vein (RHV) in all the patients. In 75.3% (113/150) of all the patients, V5d joined the RHV. In the right lateral sector (RLS), more than half (71/133, 53.4%) of the patients had an arch-like type. We summarize different patterns of liver vascular branches, providing a valuable reference for clinical surgery and liver transplantation. Cranio-caudal segmentation is more common than ventral-dorsal segmentation. The AFV can be regarded as a reliable anatomical landmark for subsegmentation in segment 8. In addition, the absence of AFV was associated with the P8 pattern.

Impact of Minimally Invasive Surgery on Anatomic Liver Segmentectomy Using the Extrahepatic Glissonean Approach

Accurate minimally invasive anatomic liver (sub)segmentectomy (MIAS) is technically demanding and not yet standardized, and its surgical outcomes are undefined. To study the impact of the minimally invasive approach on perioperative outcomes of anatomic liver (sub)segmentectomy (AS), we retrospectively studied and compared perioperative outcomes of 99 open AS (OAS) and 112 MIAS (laparoscopic 77, robotic 35) cases using the extrahepatic Glissonean approach, based on the 1:1 propensity score matched analyses. After matching (71:71), MIAS was superior to OAS in terms of blood loss (p < 0.0001), maximum postoperative serum total bilirubin (p < 0.0001), C-reactive protein (p = 0.034) levels, R0 resection rate (p = 0.021), bile leak (p = 0.049), and length of hospital stay (p < 0.0001). The matched robotic and laparoscopic AS groups (30:30) had comparable outcomes in terms of operative time, blood loss, transfusion, open conversion, postoperative morbidity and mortality, R0 resection, and hospital stay, although the rate of Pringle maneuver application (p = 0.0002) and the postoperative aspartate aminotransferase level (p = 0.002) were higher in the robotic group. Comparing the matched posterosuperior (sub)segmentectomy cases or unmatched repeat hepatectomy cases between MIAS and OAS, we observed significantly less blood loss and shorter hospital stays in MIAS. Robotic AS yielded comparable outcomes with laparoscopic AS in the posterosuperior (sub)segmentectomy and repeat hepatectomy settings, despite the worse tumor and procedural backgrounds in robotic AS. In conclusion, various types of MIAS standardized by the extrahepatic Glissonean approach were feasible and safe with more favorable perioperative outcomes than those of OAS. Although robotic AS had almost comparable outcomes with laparoscopic AS, robotics may serve to decrease the surgical difficulty of MIAS in selected patients undergoing posterosuperior (sub)segmentectomy and repeat hepatectomy.

Prevalence and clinical significance of the Sg6/Sg7 intersegmental veins based on re-evaluation of the Couinaud classification for the right posterior portal vein

Although Segment 6(Sg6) and Segment 7(Sg7) are two independent units, there are currently no clear anatomical boundary markers between Sg6 and Sg7. This study aimed to identify intersegmental veins (ISV) in the intersegmental plane of Sg6 and Sg7, and evaluate the prevalence of ISV, and its clinical significance in anatomical hepatectomy. We analyzed data from 180 patients undergoing abdominal computed tomography (CT) examination, and simultaneously performed 3D reconstruction models of the liver for each patient. The right posterior portal vein was analyzed and re-typed. Furthermore, the existence of ISV was defined, and prevalence and confluence patterns of ISV were analyzed. The author attempted to apply ISV to laparoscopic S6/S7 segmentectomy. We sorted data from the right posterior portal vein and divided it into six types. The ISV could be identified in 82.2% (148/180) of the patients, which were derived from the right hepatic vein (RHV) (91.9%) and right posterior inferior vein (IRHV) (8.1%). Ten ISV-guided laparoscopic Sg6/Sg7 segmentectomy were successfully carried out, seven patients underwent Sg6 segmentectomy, and three patients underwent Sg7 segmentectomy. There was no perioperative mortality. The median operative time was 223 min (range 181-260 min). The median blood loss was 200 ml (range 150-310 ml). The R0 resection rate was 100%. The ISV may be a candidate vessel to distinguish the boundary of the right posterior sector; it is expected to be a landmark in the liver parenchyma of anatomical hepatectomy.

Study of the Intersegmental Veins Between S5 and S8 Based on 3D Reconstruction

BACKGROUND

Anatomic resection (AR) is a surgical method for treating hepatocellular carcinoma, and identifying intersegmental planes between segments 5 (S5) and 8 (S8) remains challenging. This study aims to find reliable intersegmental veins (IVs) between them as anatomical landmarks using 3D reconstruction analysis.

METHODS

We retrospectively evaluated 57 patients who underwent multidetector-row CT scans from September 2021 to January 2023. The portal vein watershed of S5 and S8 and hepatic veins were reconstructed using 3D reconstruction analysis software. We counted and analyzed the IVs running within the intersegmental plane between S5 and S8, examined their features, and analyzed the location of the junctions between IVs and middle hepatic veins (MHVs).

RESULTS

Among the 57 patients, 43 patients (75.4%) had IVs between S5 and S8. Most patients (81.4%) had a single IV joining the MHV, while 13.9% had two IVs, one joining the MHV and the other joining the right hepatic vein (RHV). The majority of IV-MHV junctions were found in the lower part of the MHVs. The most clearly identifiable junctions between the IVs and MHVs occurred slightly below the midpoint of the horizontal planes of the second hepatic portal and the center of the gallbladder bed.

CONCLUSION

Our study identified IVs between S5 and S8 in the liver as potential anatomical landmarks during AR for hepatocellular carcinoma surgery. We found three types of IVs and provided insights on how to locate their junctions with MHVs for easier surgical navigation. However, individual anatomical variations must be considered, and preoperative 3D reconstruction and personalized surgical planning are crucial for success. More research with larger sample sizes is needed to validate our findings and establish the clinical significance of these IVs as landmarks for AR.

Comparison Between Contrast-Enhanced Computed Tomography and Contrast-Enhanced Magnetic Resonance Imaging With Magnetic Resonance Cholangiopancreatography for Resectability Assessment in Extrahepatic Cholangiocarcinoma

OBJECTIVE

To compare the diagnostic performance and interobserver agreement between contrast-enhanced computed tomography (CECT) and contrast-enhanced magnetic resonance imaging (CE-MRI) with magnetic resonance cholangiopancreatography (MRCP) for evaluating the resectability in patients with extrahepatic cholangiocarcinoma (eCCA).

MATERIALS AND METHODS

This retrospective study included treatment-naïve patients with pathologically confirmed eCCA, who underwent both CECT and CE-MRI with MRCP using extracellular contrast media between January 2015 and December 2020. Among the 214 patients (146 males; mean age ± standard deviation, 68 ± 9 years) included, 121 (56.5%) had perihilar cholangiocarcinoma. R0 resection was achieved in 108 of the 153 (70.6%) patients who underwent curative-intent surgery. Four fellowship-trained radiologists independently reviewed the findings of both CECT and CE-MRI with MRCP to assess the local tumor extent and distant metastasis for determining resectability. The pooled area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of CECT and CE-MRI with MRCP were compared using clinical, surgical, and pathological findings as reference standards. The interobserver agreement of resectability was evaluated using Fleiss kappa (κ).

RESULTS

No significant differences were observed between CECT and CE-MRI with MRCP in the pooled AUC (0.753 vs. 0.767), sensitivity (84.7% [366/432] vs. 90.3% [390/432]), and specificity (52.6% [223/424] vs. 51.4% [218/424]) (P > 0.05 for all). The AUC for determining resectability was higher when CECT and CE-MRI with MRCP were reviewed together than when CECT was reviewed alone in patients with discrepancies between the imaging modalities or with indeterminate resectability (0.798 [0.754-0.841] vs. 0.753 [0.697-0.808], P = 0.014). The interobserver agreement for overall resectability was fair for both CECT (κ = 0.323) and CE-MRI with MRCP (κ = 0.320), without a significant difference (P = 0.884).

CONCLUSION

CECT and CE-MRI with MRCP showed no significant differences in the diagnostic performance and interobserver agreement in determining the resectability in patients with eCCA.

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.

Color Doppler Intraoperative Ultrasonography Evaluation of Hepatic Hemodynamics for Laparoscopic Parenchyma-Sparing Liver Resections

BACKGROUND

Tumors involving the hepatic veins at the hepatocaval confluence often require major or extended hepatectomies. Color Doppler intraoperative ultrasonography (CD-IOUS) evaluation of liver hemodynamics to assess congestion in the veno-occlusive parenchyma provides real-time information helpful in parenchyma-sparing surgery (PSS). This study evaluated the feasibility of CD-IOUS in patients undergoing laparoscopic liver resections for such tumors and its capacity to allow PSS.

METHODS

Consecutive patients undergoing laparoscopic liver resection for tumors at the hepatocaval confluence requiring resection of at least one hepatic vein between January 2010 and August 2020 were included. Patients were divided in 3 groups: (A) patients not assessed with CD-IOUS because it would not change the scheduled operation; patients assessed with CD-IOUS and treated with (B) PSS and (C) no-PSS. Portal blood flow in the veno-occlusive parenchyma was assessed using CD-IOUS at baseline and after clamping the concerned hepatic vein.

RESULTS

The study included 43 out of 47 patients with tumors at the hepatocaval confluence. There were 19 patients in group A. Among patients assessed with CD-IOUS, the resection of 26 hepatic veins was planned: 25 were resected, and 1 was spared. Group B included 22 patients treated with PSS, whereas group C included 2 patients with resection of all veno-occlusive parenchyma. No postoperative mortality or major morbidity was observed. The median length of hospital stay was 5 days.

CONCLUSIONS

Selected patients with tumors involving the hepatocaval confluence can be safely approached using laparoscopy. CD-IOUS evaluation of the veno-occlusive area can increase the success rate of PSS.

Study on the portal ramification pattern of the right anterior sector of the liver and a unique medial branch (PV8c) of the right anterior portal vein

Aim

The concept of Couinaud segmentation is widely used in clinical practice. However, there were no definite anatomical landmarks between segments V and VIII. Therefore, segmentation of the right anterior sector is still controversial. We aimed to investigate the portal segmentation of the right anterior sector using 3D image analysis, and to reveal the existence of the medial branch (PV8c), a unique, characteristic branch of the right anterior portal vein.

Methods

The ramification form and pattern of the tertiary portal branch of the right anterior portal vein were retrospectively analyzed, and the frequency of PV8c was evaluated in 261 patients between January 2016 and June 2020.

Results

The ramification pattern of tertiary portal branches of the right anterior portal vein was classified into four types: craniocaudal, 28.0% of patients; ventrodorsal, 21.8%; trifurcation, 39.5%; and quadfurcation, 5.7%, and each type was further subdivided into six patterns by focusing especially on the caudal branches. The ramification pattern in the remaining 5.0% of the livers did not belong to the above-mentioned four types. The PV8c branch was identified in 140 of 261 livers (53.6%); the mean proportion of the feeding area of PV8c in the whole liver volume was 3.4%.

Conclusion

Since the ramification pattern of tertiary portal branches of the right anterior portal vein does not necessarily show a single pattern, it is important to confirm the portal vein branching in each case during hepatectomy. This is the first study of the details of PV8c by 3D computed tomography.

Artificial intelligence enhances the accuracy of portal and hepatic vein extraction in computed tomography for virtual hepatectomy

BACKGROUND/PURPOSE

Current conventional algorithms used for 3-dimensional simulation in virtual hepatectomy still have difficulties distinguishing the portal vein (PV) and hepatic vein (HV). The accuracy of these algorithms was compared with a new deep-learning based algorithm (DLA) using artificial intelligence.

METHODS

A total of 110 living liver donor candidates until 2017, and 46 donor candidates until 2019 were allocated to the training group and validation groups for the DLA, respectively. All PV or HV branches were labeled based on Couinaud's segment classification and the Brisbane 2000 Terminology by hepato-biliary surgeons. Misclassified and missing branches were compared between a conventional tracking-based algorithm (TA) and DLA in the validation group.

RESULTS

The sensitivity, specificity, and Dice coefficient for the PV were 0.58, 0.98, and 0.69 using the TA; and 0.84, 0.97, and 0.90 using the DLA (P < .001, excluding specificity); and for the HV, 0.81, 087, and 0.83 using the TA; and 0.93, 0.94 and 0.94 using the DLA (P < .001 to P = .001). The DLA exhibited greater accuracy than the TA.

CONCLUSION

Compared with the TA, artificial intelligence enhanced the accuracy of extraction of the PV and HVs in computed tomography.

Laparoscopic anatomic combined subsegmentectomy of segment 8 via the tailored strategy using digital intelligent technology

INTRODUCTION

Segment 8 is considered the largest liver segment, and its portal vein branches are generally divided into four parts, including ventral, dorsal, dorsolateral and medial branches (Shindoh et al., 2010; Takayasu et al., 1985) [1,2]. An anatomic combined subsegmentectomy could satisfy both the oncological quality of anatomical resection and the safety of parenchyma sparing principle if a small hepatocellular carcinoma is located between the hepatic subsegments (Berardi et al., 2021) [3]. Yet, laparoscopic anatomic combined subsegmentectomy of segment 8 is still technically challenging. The development of digital intelligent technology has made it possible to tailored preoperative planning and accurate intraoperative navigation in laparoscopic surgery.

VIDEO

A 57-year-old man underwent a routine CT scan and was found to have a mass occupation in segment 8 of the liver. Three-dimensional reconstruction was performed to evaluate liver anatomy, vascular variations, and volume of each vascular unit as well as the location of the tumor, its relationship with the liver anatomy, and the Glissonian pedicles feeding the tumor-bearing area. Based on the reconstructed model, resection was planned aiming to the narrowest but oncologically safe anatomical tumor-bearing area. Upon evaluation, anatomic combined subsegmentectomy of segment 8 (ventral and medial subsegments) was confirmed. The operation was performed precisely under assistance of the Laparoscopic Hepatectomy Navigation System (LHNS, software copyright No. 2018SR840555) (Yang et al., 2020) [4].

RESULTS

The operation lasted 200 min with 50 ml intraoperative blood loss. There were no postoperative complications, and the patient was discharged after 6 days.

CONCLUSION

Digital intelligent technology could provide tailored strategy for laparoscopic liver surgery, which makes laparoscopic anatomic combined subsegmentectomy of segment 8 feasible and effective.

Re-evaluation of the Couinaud classification for segmental anatomy of the right liver, with particular attention to the relevance of cranio-caudal boundaries

BACKGROUND

Although the Couinaud classification of liver segments has been challenged by several studies, whether the cranio-caudal boundaries can be delineated in the right liver has not yet been assessed. This study scrutinized the third-order branching pattern of the portal vein in the right liver with attention to the validity of cranio-caudal segmentation.

METHODS

Three-dimensional reconstruction of the portal vein and hepatic vein, using non-contrast-enhanced magnetic resonance imaging was performed in 50 healthy participants.

RESULTS

In the right paramedian sector, the portal vein ramified into 2 thick P8s (P8vent and P8dor) in all the participants. Additional thick P8s that ran laterally and/or medially (P8lat and/or P8med) were observed in 18 (32%) participants. In contrast, multiple thin P5s, ranging in number from 2 to 6 (median, 4), branched from the right paramedian trunk, the right portal trunk, and/or even from P8s. In the right lateral sector, an arch-like type in which multiple P6s ramified from a single thick P7 was observed in 26 (52%) participants. A bifurcation type composed of a single P7 and a single P6 was observed in 23 (46%) participants, and a trifurcation type was observed in 1 participant.

CONCLUSION

No clear cranio-caudal intersegmental plane could be delineated in the right liver in most of the participants. The resection of a whole Couinaud segment in the right liver should not be regarded as a systematic, anatomic resection from an oncologic viewpoint. In contrast, detailed information on the third-order portal vein ramification pattern is likely to be helpful when performing smaller anatomic resections.

Study of the Portal Branches Arising from the Cranial Part of the Umbilical Portion of the Left Portal Vein: Implications for Anatomic Right Hepatic Trisectionectomy

BACKGROUND

In "anatomic" right hepatic trisectionectomy for advanced perihilar cholangiocarcinoma, the left hepatic duct is divided at the left side of the umbilical portion (UP) of the left portal vein (LPV). For this reason, the left hepatic duct is completely detached from the UP after all division of the portal branches arising cranially from the UP. However, little is known about these thin portal branches.

METHODS

Using 3D imaging processing software, we examined the portal branches arising cranially from the UP of the LPV in 100 patients who underwent multidetector row computed tomography (MDCT). Special attention was paid to the portal branch running to the left lateral sector, designated as the left cranio-lateral branch.

RESULTS

The left cranio-lateral portal branch number was 0 in 57 patients, 1 in 32 patients, and 2 in 11 patients. Thus, 54 left cranio-lateral branches were identified, arising from near the cul-de-sac of the UP, from near the elbow of the LPV, or from the UP trunk. The median volume of the territory supplied by the left cranio-lateral portal branch was 21 mL (range, 5-47 mL), and the median ratio to the left lateral sector was 11.8% (range, 1.7-25.0%).

CONCLUSION

Approximately 40% of patients had the left cranio-lateral portal branches arising cranially from the UP and running to the left lateral sector. When planning anatomic right hepatic trisectionectomy, the presence or absence of this branch should be checked by using 3D imaging with MDCT.

Anatomy of the Right Anterior Sector of the Liver and Its Clinical Implications in Surgery

BACKGROUND

Surgery remains the gold standard both for delimited hepatocellular carcinoma by selective anatomic liver segentectomy and for colorectal liver metastases by parenchymal sparing liver resection. Right anterior sector (RAS) (segments V-VIII; Couinaud) is the largest and most difficult sector to operate on. A better knowledge of its segmentation could prevent postoperative remnant liver ischemia and its impacts on patient's survival.

METHODS

A literature search was conducted in PubMed for papers on anatomy and surgery of the right anterior sector.

RESULTS

Segmentation of the RAS depended of the anatomic variations of the third-order portal branches. Cranio-caudal segmentation was the most commonly found (50-53%), followed by ventro-dorsal (23-26%), trifurcation (13-20%), and quadrifurcation types (5-11%). Ventral and dorsal partial or total subsegmentectomy seemed accessible in 47 to 50% of patients, including bifurcation, trifurcation, and quadrifurcation types, and could spare up to 22% of the total liver volume. The RAS hepatic vein was present in 85-100% of the patients and could be used as a landmark between RAS dorsal and ventral part in 63% of patients. Reported overall morbidity rate of RAS subsegmentectomy ranged from 33 to 59% among studies with a postoperative major complication rate (Clavien-Dindo ≥ III) ranging around 18% and a biliary leakage rate from 16 to 21%. In-hospital reported mortality rate was low (0-3%), and results were comparable to "classic" liver resections. RAS subsegmentectomy remains a complex procedure; median operating time ranged from 253 to 520 min and median intraoperative blood loss reached 1255 ml.

CONCLUSION

Better knowledge of RAS anatomy could allow for parenchymal preservation by using subsegmentectomy of the RAS, selective or as a part of a major hepatectomy.

Aberrant Right Gastric Vein Directly Communicating with Left Portal Vein System

In 3 patients with primary hepatic malignancies, a communication between the right gastric vein and the left portal vein system was recognized at angiography. The right gastric vein entered directly into the left lateral portal veins in 2 patients and into the left medial portal veins in one. Portal angio-CT performed in one patient demonstrated a specific defect only in the left lateral superior area of the liver, consistent with the segmental opacification of the portal vein branch recognized on the angiogram. This rare communication was seen in 3 (1.5%) of 200 consecutive patients who underwent celiac angiography and is most likely an anomaly in which the right gastric vein directly enters the left portal vein instead of the portal vein trunk. When interpreting a filling defect not associated with a mass lesion on portal angio-CT for hepatic neoplasms or the right gastric vein communicating with the left portal vein system on the angiogram, this particular anomaly should be considered.

Three-Dimensional Black Blood Mr Angiography of the Liver during Breath Holding

In 2-D time-of-flight MR angiography (2-D TOF MRA) of the liver, artifacts caused by respiratory motion are unavoidable. Therefore, a 3-D black blood MRA of the liver was attempted in 7 healthy volunteers, using a 3-D gradient echo sequence which allows imaging during breath holding. 2-D TOF MRA was performed as well. In all subjects, 3-D MRA allowed visualization of the trunk, 1st-, and 2nd-order branches of the portal vein without interruption. Right 3rd-order branches were visualized without interruption in 6 of 7 subjects (85%). However, with 2-D MRA, the transverse portion of the left main portal vein could not be visualized in any subject, and the periphery of the portal vein was less clear than with 3-D MRA.

Variation or newly identified glissonian pedicles between the lateral and medial sections of the liver, using cadaver dissection

Purpose

Studies of liver anatomy have developed alongside clinical achievements, as these types of research complement each other. The aim of this study is to determine whether or not the portal vein branches (P4d) in 'Nagino's trisectionectomy' exist, and to examine their characteristics using cadaver dissection.

Methods

From April 2012 to July 2012, 31 adult cadavers were delicately dissected. We defined a 'NewGP' as an extra glissonian pedicle (GP) other than the traditional GPs that supply segments II, III, IVa, and IVb in the ordinary direction, and anatomically located superior to the umbilical fissure (UF).

Results

We identified 'NewGPs' based on the UF and UF vein. The incidence of 'NewGPs' was 30/31 (96.8%). The diameter of the 'NewGPs' ranged from 3.5 to 5.6 mm, which was not significantly different from that of traditional GPs (II-, III-, or IV-GP), which have diameters ranging from 3.7 to 9.7 mm.

Conclusion

We think that the P4d in 'Nagino's trisectionectomy' correspond to the 'IVa NewGP' and the additional pedicle. We believe the clinical significance of the 'NewGP' is to complement the traditional II, III, IVa, and IVb pedicles in supplying the liver.

Concepts for Liver Segment Classification: Neither Old Ones nor New Ones, but a Comprehensive One

Concepts dealing with the subdivision of the human liver into independent vascular and biliary territories are applied routinely in radiological, surgical, and gastroenterological practice. Despite Couinaud's widely used eight-segments scheme, opinions on the issue differ considerably between authors. The aim of this article is to illustrate the scientific basis for understanding and harmonizing inconsistencies between seemingly contradictory observations. Possible clinical implications are addressed.

Segmentectomy of the liver

Segmentectomy is anatomical resection of segments based on the classification of Couinaud. This procedure is performed mainly for hepatocellular carcinoma. Invasion of portal vein and intrahepatic metastases often occur with hepatocellular carcinoma. Thus, it is desirable to perform anatomical resection of the cancer-bearing areas for curative purpose. However, segmentectomy is selected when extensive resection must be avoided to preserve liver function. There are major differences between segmentectomy of the left hemiliver (Sg 2-4) and right hemiliver (Sg 5-8). In the former, the branches (third-order branches) arising from the umbilical portion of the portal vein can be ligated prior to liver resection. In the latter, manipulation is difficult. Therefore, ultrasonically guided segmental staining is performed by puncturing the portal branch and injecting a dye. This report described techniques for segmentectomy.

Total or partial anatomical resection of segment 8 using the ultrasound-guided finger compression technique

BACKGROUND

A new surgical technique to define intra-operatively segmental and subsegmental areas of the liver using ultrasound-guided bimanual liver compression has been recently described. However, this technique does not allow disclosure of the subsegmental ventral (S8v) and dorsal (S8d) portions of segment 8 (S8). Another technique that overcomes these limitations is described.

METHODS

Six patients with hepatoma, cirrhosis and no evidence of portal vein thrombosis were submitted to the procedure. Demarcation of the resection area was achieved using ultrasound-guided finger compression of the S8 subsegmental portal branches (P8v and P8d).

RESULTS

The procedure was feasible in all patients and demarcation was always obtained within 1 min of bimanual ultrasound-guided compression. In one patient, the entire S8 was resected. In the remaining five patients, the dorsal (four patients) or the ventral (one patient) portion was removed, respectively. There was no mortality or morbidity and no blood transfusions were administered.

CONCLUSIONS

Disclosure of the subsegmental portions of S8 using the ultrasound-guided compression technique was feasible, safe and effective, and represents the completion of the ultrasound-guided compression technique for performing segmental and subsegmental anatomical resection of the liver.

Portal vein normal anatomy and variants: implication for liver surgery and portal vein embolization

The normal anatomy of the portal vein is defined as a division of the main portal vein into two branches-the left (supplying segments II, III, and IV) and right portal veins; the right dividing secondarily into two branches-the anterior (supplying segments V and VIII) and the posterior (supplying segments VI and VII) portal veins. Variants are frequent and account for 20 to 35% of the population. The most frequent variants are portal trifurcation with division of the main portal vein into the left, right anterior, and posterior branches, and the early origin of the right posterior branch directly from the portal vein. The presence of portal vein variants increases the risk of bile duct hilar anatomical variation. These variants must be diagnosed before complex hepatectomy, split or living donor transplantation, and before complex interventional procedures such as portal vein embolization. The purpose of this article is to review normal and variant portal venous anatomy and their implications for liver surgery and preoperative portal vein embolization.

Spatial relationship between intrahepatic artery and portal vein based on the fusion image of CT-arterial portography (CTAP) and CT-angiography (CTA): new classification for hepatic artery at hepatic hilum and the segmentation of right anterior section of the liver

PURPOSE

To clarify the variations of the intrahepatic artery and portal vein and to verify the proper segmentation for the right anterior section of the liver.

MATERIALS AND METHODS

CT during arterial portography and CT angiography were performed on 64-slice multi detector row CT in 147 patients. All images were transferred to a workstation for analysis using multi-image-fusion mode. We investigated the spatial relationship between hepatic artery and portal vein in the right hemiliver and the segmentation of the right anterior hepatic artery and portal vein.

RESULTS

The spatial anatomy of right hepatic arteries and portal vein was (1) anterior and posterior hepatic artery run superior and inferior to anterior portal vein, respectively (47.6%), (2) one anterior hepatic artery runs superior to and another one runs inferior to anterior portal vein (15%), (3) anterior and posterior hepatic arteries run superior to anterior portal vein (11.6%), (4) anterior and posterior hepatic arteries run inferior to anterior portal vein (7.5%), and (5) one posterior hepatic artery runs superior to and another one runs inferior to anterior portal vein (6.8%). The combined anatomy of right anterior artery and portal vein with regard to segmentation was classified as (1) dorso-ventral (26.5%), (2) dorso-ventral and inferior (10.9%), (3) multiple (18.4%), and (4) superior and inferior segments (1.4%).

CONCLUSION

There are various types of spatial anatomy of intrahepatic artery and portal vein. The hepatic arteries as well as portal veins of right anterior section of the liver could be divided into dorsal and ventral, not superior and inferior.

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.

Extended right trisegmentectomy using in situ hypothermic perfusion with modified HTK solution for a large intrahepatic cholangiocarcinoma

The technique of right hepatic trisegmentectomy has been standardized for large tumors that involve the right lobe and extend into the medial segment of the left lobe. However, these tumors are deemed unresectable if they encroach across the falciform ligament into the left lateral segment. We report the technique of extended right trisegmentectomy in a patient with a large intrahepatic cholangiocarcinoma that involved the right lobe of the liver and extended into the medial and lateral segments of the left lobe. The resection was performed by using total hepatic vascular isolation and in situ hypothermic perfusion with modified histidine-tryptophan-ketoglutarate (HTK) solution into the left lateral segment. The biliary enteric anastomosis was constructed using a double hepaticojejunostomy to Segments II and III bile ducts. The procedure allowed safe parenchymal dissection with preservation of the blood supply to Segments II and III. Furthermore, in situ hypothermic perfusion protected the remnant liver from the deleterious effects of warm ischemia during parenchymal dissection and facilitated postoperative recovery. To the best of our knowledge, this is the first report of extended right trisegmentectomy for the treatment of intrahepatic cholangiocarcinoma in the Western literature.

Preoperative evaluation of hepatic vasculature by three-dimensional computed tomography in patients undergoing hepatectomy

BACKGROUND

Hepatectomy is particularly difficult when the tumor is large, close to the inferior vena cava or the main trunk of the hepatic or portal vein, or in the caudate lobe, as well as when the operation is a re-hepatectomy, because two-dimensional computed tomography (CT) often does not clearly show tumor location relative to blood vessels.

STUDY DESIGN

To evaluate the efficacy of three-dimensional computed tomography (3D-CT), reconstructed from multidetector-row computed tomography (MD-CT) with contrast, MD-CT was performed in 17 patients before hepatectomy.

RESULTS

The third-order branches of the hepatic artery and the portal vein were clearly shown in all cases. Both the hepatic vein, which drained the same segment that the portal vein fed, and the portal vein were also clearly shown. These vessels could be visualized from any perspective. In 2 patients who underwent hemihepatectomy, large tumors (23.0 and 17.0 cm) displaced the vasculature, but the positions of tumor and vessels could be precisely evaluated by 3D-CT. In patients who required replacement of the vena cava with synthetic grafts, the distance and direction of pressure to IVC by tumor was accurately estimated by 3D-CT. In patients who were limited to segmentectomy or partial hepatectomy because of prior hepatectomy or tumor position, evaluation of the glissons was facilitated by 3D-CT.

CONCLUSIONS

Three-dimensional-CT was extremely useful for preoperative simulation because it provided important information that could not be obtained with 2D-CT.

"Anatomic" right hepatic trisectionectomy (extended right hepatectomy) with caudate lobectomy for hilar cholangiocarcinoma

BACKGROUND

The techniques of right hepatic trisectionectomy are now standardized in patients with hepatocellular or metastatic carcinoma, but not in those with hilar cholangiocarcinoma.

METHODS

Under preoperative diagnosis of hilar cholangiocarcinoma, 8 patients underwent "anatomic" right hepatic trisectionectomy with en bloc resection of the caudate lobe and the extrahepatic bile duct, in which the bile ducts of the left lateral section were divided at the left side of the umbilical fissure following complete dissection of the umbilical plate.

RESULTS

Liver resection was successfully performed, and all patients were discharged from the hospital in good condition, giving a mortality of 0%. All patients were histologically diagnosed as having cholangiocarcinoma. The proximal resection margins were cancer-negative in 7 patients and cancer-positive in 1 patient. Four patients with multiple lymph node metastases died of cancer recurrence within 3 years after hepatectomy. One patient died of liver failure without recurrence 42 months after hepatectomy. The remaining 3 patients without lymph node metastasis are now alive after more than 5 years.

CONCLUSIONS

Anatomic right hepatic trisectionectomy with caudate lobectomy can produce a longer proximal resection margin and can offer a better chance of long-term survival in some selected patients with advanced hilar cholangiocarcinoma.

[Portal vein: variations of its branches (about 32 dissections)]

PURPOSE

The aim of this study is to precise the variations of portal vein branches and also to elucidate anatomic basis of partial hepatectomy.

MATERIAL AND METHODS

Thirty-two post-mortem specimens, with ages ranged from one day to sixty-five years in both two sexes, were dissected. Latex and Rhodopas were used for visualizing and drawing the portal vein course and its branches.

RESULTS

Nine types of different variations of portal vein branches were observed. Most of cases were similar to those previously reported in literature. But four types must be especially noted, because they were not available in literature.

DISCUSSION

this study updates the anatomy of portal vein and its tributaries, and also finds out four types of distribution which must be known by surgeons with regards to partial hepatectomy.

Proposal for a reclassification of liver based anatomy on portal ramifications

BACKGROUND

Portal branching patterns that differ from those previously described are occasionally encountered during liver surgery.

METHODS

A total of 60 patients with normal intrahepatic venous anatomy underwent helical computed tomography during arterial portography (CTAP). Next, 3 dimensional portograms were reconstructed to verify the locations of the portal veins. Portal branching patterns in the right hemiliver were assessed.

RESULTS

In all 60 patients examined, the right anterior portal vein bifurcated into the ventral and dorsal branches. In 42 (70%) of 60 patients, some branches arose from the right posterior portal trunk. Between 1 and 3 branches (mean 2.3 branches per patient) coursed cranially, between 2 and 5 branches (mean 3.2 branches per patient) coursed caudally, and between 1 and 2 branches (mean 1.3 branches per patient) coursed laterally.

CONCLUSIONS

We propose that the right liver should be divided into 3 segments, which are designated as the right anterior, middle, and posterior segments.

N/A

N/A

Relation between hepatic and portal veins in the right paramedian sector: proposal for anatomical reclassification of the liver

Although a right liver graft without a middle hepatic vein resulted in potential venous congestion in the right paramedian sector, the details of the hepatic venous distribution in the right paramedian sector have not been established. In this study, the ramification patterns of the hepatic veins draining the right anterosuperior segment (S8) and the relation between the hepatic and portal veins were assessed using multislice computed tomography in 44 patients without lesions in the liver. All 52 drainage veins of the ventral area of S8 joined the middle hepatic vein, and all 48 drainage veins of the dorsal area joined the right hepatic vein. The hepatic vein crossing between the ventral and dorsal areas was observed in each patient examined. Therefore, we propose a reclassification wherein the right paramedian sector is divided into ventral and dorsal segments. This new classification may contribute to the development of new and safer surgical procedures, including more limited resection and right lobe adult living donor liver transplantation to avoid graft congestion.

Relationship between left biliary duct system and left portal vein: evaluation with three-dimensional portocholangiography

PURPOSE

To investigate the relationship between the left biliary duct system and the left portal vein by using in vivo analysis of the human liver with three-dimensional portocholangiography.

MATERIALS AND METHODS

Twenty-seven patients underwent helical computed tomography during both arterial portography and cholangiography. Three-dimensional portocholangiograms were reconstructed to evaluate the relationship between the left biliary duct system and the left portal vein, in particular the umbilical portion.

RESULTS

In 16 (59%) patients, segment II and III ducts united just above the umbilical portion or laterally to it, and the segment IV duct joined medially to the umbilical portion. In eight (30%) patients, segment III and IV ducts united medially to the umbilical portion and the segment II duct joined at a point close to the hepatic hilum. In three (11%) patients, three ducts from segments II-IV united at a position immediately medial to the umbilical portion.

CONCLUSION

Three types of left bile duct anatomy were seen in relation to the left portal vein.

Human liver caudate lobe and liver segment

Recently, the caudate lobe has seemed to be the final target for aggressive cancer surgery of the liver. This lobe has five surfaces: the dorsal, left and hilar-free surfaces and the right and ventral-border planes. Surgeons have divided the caudate lobe into three parts: Spiegel's lobe, which is called the 'caudate lobe and papillary process' by anatomists, the caudate process, viewed as almost the same entity by anatomists, and the paracaval portion corresponding to the dorsally located parenchyma in front of the inferior vena cava. All three parts are supplied by primary branches originating from the left and right portal veins, including the hilar bifurcation area. The hilar bifurcation branch often (50%) supplies the paracaval portion and it sometimes (29%) extends its territory to Spiegel's lobe. It was postulated by Couinaud that the paracaval portion or the S9 is not defined by its supplying portal vein branch but by its 'dorsal location' in the liver. Couinaud's caudate lobe or dorsal-liver concept cause, and still now causes, great logical confusion for surgeons. We attempt here to describe the margins of the lobe, border branches of the portal vein, the left/right territorial border of the portal vein or Cantile's line and other topics closely relating to the surgery within these contexts. Finally, the caudate lobe as a liver segment will be discussed.

Complications of percutaneous transhepatic portal vein embolization

PURPOSE

Percutaneous transhepatic portal vein (PV) embolization (PTPE) is a useful preoperative procedure for extended liver resection. The purpose of the present study was to assess the frequency of technical complications of PTPE and to discuss the risks of this procedure.

MATERIALS AND METHODS

PTPE was performed in 46 patients. Forty-seven procedures were performed because an initial puncture failure required that the procedure be performed twice in one patient. The technical success rate and technical complications were assessed. Complications were analyzed with regard to approach methods and puncture sites. Approach methods were categorized as contralateral or ipsilateral. Puncture sites were categorized into anterior, posterior, and lateral segments. The results were compared statistically with use of the Fisher exact test.

RESULTS

Technical success was achieved in 45 of 47 procedures (95.7%). Complications occurred in seven of 47 procedures (14.9%), including pneumothorax in two, subcapsular hematoma in two, arterial puncture in one, pseudoaneurysm in one, hemobilia in one, and PV thrombosis in one. Subcapsular hematoma and pseudoaneurysm occurred in the same procedure. No patient died as a result of complications. There was no significant difference between the contralateral and ipsilateral approaches. The incidence of complications was significantly higher in procedures involving puncture of the posterior segment than in those involving puncture of the anterior segment (P =.0374).

CONCLUSION

In cases in which the anterior segment cannot be visualized for puncture, PTPE via the lateral segment or transileocolic portal embolization should be considered rather than PTPE via the posterior segment.

Location of the ventral margin of the paracaval portion of the caudate lobe of the human liver with special reference to the configuration of hepatic portal vein branches

The topographic anatomy of the ventral margin of the paracaval portion of the caudate lobe of the human liver has not been clearly described to date. To this end we hypothesize the existence of a precaudate plane, a flat or slightly curved plane defined by the ventral margins of the ligamentum venosum and the hilar plate. Using 76 cadaveric livers, we investigated whether the paracaval portion of the caudate lobe extended ventral to this plane and whether the paracaval caudate branch of the portal vein (PC) ran through this plane to its ventral side. In 28 of the specimens (36.8%), the PC extended over the plane to a variable depth: less than 10 mm in 10 specimens, 10-20 mm in 10, and more than 20 mm in eight specimens. This ventral extension of the PC consistently included its penetration into the dome-like area under the terminals of the three major hepatic veins; therefore, the ventrally extended PC often interdigitated with these veins and their tributaries (in practice, the ventral margin of the paracaval portion of the caudate lobe could generally be considered to run alongside the middle hepatic vein). Moreover, the ventral extension of the PC often reached the upper, diaphragmatic surface or the dorsal surface of the liver immediately to the right of the inferior vena cava. Several branches (termed border branches) in the ventral extension were difficult to identify as belonging to the PC. We discuss both the marginal configuration of the paracaval portion of the caudate lobe and how to identify and operate on the ventrally extended PC and related border branches during liver surgery.

Focal lesions in cirrhotic explant livers: pathological evaluation and accuracy of pretransplantation imaging examinations

Imaging detection and diagnosis of hepatocellular carcinomas (HCCs) and dysplastic nodules (DNs) in cirrhotic patients is important because the number, size, and type of focal lesions strongly influence patient management. Focal lesions detected by imaging examinations during pretransplantation evaluation were correlated with focal lesions detected during detailed pathological examination of 49 cirrhotic explant livers. Within 6 months before transplantation, color Doppler ultrasonography (US), contrast-enhanced computed tomography (CT), and magnetic resonance (MR) imaging were performed in 94%, 33%, and 55% of patients, respectively. In 2% to 8% of patients, different types of benign focal lesions were present, and a considerable proportion was interpreted as (pre)malignant on imaging examination. US detected only the largest HCCs (patient sensitivity, 40%; specificity, 100%) and no DNs. On a per-patient basis, contrast-enhanced CT and MR imaging had poor sensitivity (20% and 27%, respectively) and good specificity (100% and 94%, respectively) for DNs. Patient sensitivity and specificity of both techniques for HCC were reasonable (50% for CT, 70% for MR imaging) and good (79% for CT, 82% for MR imaging), respectively. Neither technique was able to detect smaller (pre)malignant lesions. As a consequence, 10% of patients underwent transplantation, although they exceeded the tumor number limit. Currently used imaging techniques cannot correctly determine the exact tumor burden in some cirrhotic patients. Regular contrast-enhanced MR examination of cirrhotic patients waiting for liver transplantation is the best tool for the early detection of (pre)malignant lesions.

Effectiveness of systematized hepatectomy with Glisson's pedicle transection at the hepatic hilus for small nodular hepatocellular carcinoma: retrospective analysis

BACKGROUND

The effectiveness of systematized hepatectomy with transection of Glisson's pedicle at the hepatic hilus in patients with small nodular hepatocellular carcinoma (HCC) has not been confirmed.

METHODS

Surgical outcomes were reviewed in 204 patients with single nodular HCCs less than 5 cm in greatest diameter, including 68 patients with tumors that showed extranodular growth and 136 patients with tumors that did not, who had undergone curative hepatectomy (partial hepatic resection, n = 114; systematized hepatectomy, n = 90) from 1990 through 1994.

RESULTS

The rates of microscopic vascular invasion and intrahepatic metastasis were significantly higher in patients who had single nodular HCCs with extranodular growth (34% and 49%) than in patients who had single nodular HCCs without extranodular growth (13%, P =.001, and 4%, P <.001). The 5-year survival rate in patients who had single nodular HCCs with extranodular growth was significantly greater after systematized hepatectomy (67%) than after partial hepatic resection (21%, P =.0002). Multivariate analysis showed that the type of operation was an independent prognostic factor in patients with single nodular HCCs with extranodular growth (P =.0008).

CONCLUSIONS

Systematized hepatectomy with Glisson's pedicle transection at the hepatic hilus should be performed in patients who have single small nodular HCCs with extranodular growth because these tumors often invade within the liver sector containing the tumor.

Configuration of the right portion of the caudate lobe with special reference to identification of its right margin

The configuration of the right portion of the caudate lobe (CL), and especially the exact location of its right margin, remains obscure. This study aimed to identify this right margin according to reliable landmarks suitable for use during clinical examinations and surgery: (1) the bifurcation of the right portal vein, (2) the end of the right hepatic vein, and (3) the notch on the gallbladder fossa. The plane defined by these three landmarks is called the right paracaval plane. Dissection of 55 livers demonstrated that the entire CL was usually contained within the left half of the specimen after cutting along the right paracaval plane (Type A: 65.4%, 36/55). However, its right portion sometimes extended beyond this plane into the right half of the liver (34.6%, 19/55), forming one or two islands when viewed from the paracaval plane (Types B and C). We found two separate marginal configurations among the 19 rightward extensions of the paracaval portion: a tree-like, deep protrusion (11/19) and a relatively smooth border (8/19). The present results suggest the existence of reliable landmarks that will allow a right-side limit for surgical resection of the CL to be established: (1) the right paracaval plane (60% reliability), (2) 10 mm to the right of the plane, including the terminal of the right hepatic vein (80% reliability), and (3) the widest margin, including the 30 mm to the right of the right paracaval plane, the right side running along the inferior vena cava, and the diaphragmatic surface around the end portions of the three main hepatic veins (100% reliability).

Intrahepatic inflow areas of the drainage vein of the gallbladder: analysis by angio-CT

BACKGROUND

The drainage veins of the gallbladder (cystic veins) are important hepatic metastatic routes of gallbladder cancer. We studied the cystic vein inflow portions of the intrahepatic vessels by computed tomography during angiography (angio-CT).

METHODS

The subjects were 27 unoperated pancreatic-biliary patients. After superselective catheterization of the cystic artery, angio-CT was performed, and cystic veins and sinusoidal filling were visualized. We identified the cystic vein inflow routes and the vessels they fed.

RESULTS

We found 72 cystic veins in 26 patients. All cystic veins flowed into the intrahepatic portal branches or sinusoids. The cystic veins took either of two routes: one into the liver through the hepatic hilum (17 patients, 21 veins), taken mainly by the portal branch for subsegment 4a (P4a), the anterior portal branch, and the umbilical portion of the portal branch; and the other through the hepatic bed (23 patients, 51 veins), taken mainly by S4a sinusoid, S5 sinusoid, P4a, and P5.

CONCLUSIONS

Angio-CT is useful for detecting the cystic vein inflow portions of the intrahepatic vessels. It makes possible identification of areas where there is a possibility for micrometastasis of the gallbladder cancer.

Anatomy of the right anterosuperior area (segment 8) of the liver: evaluation with helical CT during arterial portography

PURPOSE

To evaluate the segmental anatomy of the right anterosuperior area (segment 8) of the liver by using helical computed tomography during arterial portography (CTAP).

MATERIALS AND METHODS

Twenty-seven patients without lesions at segment 8 underwent helical CTAP. Three-dimensional portograms were reconstructed to verify the course of the portal veins. The number of subsegmental branches, in addition to the branching point and the distribution in segment 8, was assessed.

RESULTS

In 25 (93%) patients, the dorsal branch of segment 8 gave rise to dorsally directed branches posterior to the right hepatic vein. In only four (25%) of 16 patients in whom the medial branch of segment 8 arose near the porta hepatis, the long paracaval portal branch of the caudate lobe extended upward above the interval between the middle and right hepatic veins.

CONCLUSION

In most of the patients, the dorsal branches of segment 8 supplied the dorsocranial area of the right lobe posterior to the right hepatic vein. The paracaval portion of the caudate lobe was limited to below the interval between the middle and right hepatic veins in the majority of patients who showed medial branches of segment 8 arising near the porta hepatis. Recognition of this vascular anatomy is clinically important for preoperative evaluation of hepatic tumors in segment 8 because it may contribute to a safer surgical approach.

Right trisegment portal vein embolization for biliary tract carcinoma: technique and clinical utility

BACKGROUND

Right portal vein embolization has become popular in preparation for right hepatic lobectomy. However, right trisegment portal vein embolization (R3PE) is not well established.

METHODS

We performed R3PE in 15 patients with biliary tract carcinoma and 1 patient with primary sclerosing cholangitis. We used 2 types of 5.5 F triple-lumen balloon catheters to embolize portal branches of the right trisegment (the left medial, the right anterior, and the right posterior segments).

RESULTS

R3PE was successful in all patients without any complications. The calculated volume of the right lobe significantly (P < .01) decreased from 650 +/- 161 cm3 before embolization to 585 +/- 143 cm3 after embolization; the volume of the left lateral segment significantly (P < .0005) increased from 240 +/- 58 cm3 to 361 +/- 66 cm3. The volume of the left medial segment was unchanged. The volume gain of the left lateral segment was larger in patients with R3PE than in those patients (n = 41) with right portal vein embolization (122 +/- 39 cm3 vs 66 +/- 35 cm3; P < .0001). Two of the 16 patients underwent only laparotomy because of peritoneal dissemination, and the remaining 14 patients underwent right hepatic trisegmentectomy with caudate lobectomy. In addition, portal vein resection was also performed in 5 patients, and pancreatoduodenectomy and right hemicolectomy was performed in 3 patients. One patient died of posthepatectomy liver failure 87 days after surgery, a mortality rate of 7.1% (1/14 patients).

CONCLUSIONS

R3PE is more useful than standard right portal vein embolization in preparation for right hepatic trisegmentectomy and has the potential to increase the safety of this high-risk surgery for patients with biliary tract carcinoma.

A new technical aspect of ultrasound-guided liver surgery

Nowadays, resective hepatic surgery should be considered an echo-guided surgical procedure to guarantee that effective anatomical resection is accomplished. We describe a simple and original technique guided by intraoperative ultrasonography (IOUS), called the hooking technique, that enables the ligation sites of the intrahepatic vessels during systematic segmentectomy to be chosen precisely. Together with other IOUS-guided techniques described previously, the hooking technique provides a further guarantee for the successful execution of anatomical and radical liver resection.