Impact of the inferior vena cava morphology on fluid dynamics of the hepatic veins

We reported previously that a large vertical interval between the hepatic segment of the inferior vena cava (IVC) and right atrium (RA), referred to as the IVC-RA gap, was associated with more intraoperative bleeding during hemi-hepatectomy. We conducted a computational fluid dynamics (CFD) study to clarify the impact of fluid dynamics resulting from morphologic variations around the liver. The subjects were 10 patients/donors with a large IVC-RA gap and 10 patients/donors with a small IVC-RA gap. Three-dimensional reconstructions of the IVC and hepatic vessels were created from CT images for the CFD study. Median pressure in the middle hepatic vein was significantly higher in the large-gap group than in the small-gap group (P = 0.008). Differences in hepatic vein pressure caused by morphologic variation in the IVC might be one of the mechanisms of intraoperative bleeding from the hepatic veins.

Quantitative anatomy of the large variant right hepatic vein: A systematic three-dimensional analysis

Anatomical variations of the right hepatic vein, especially large variant right hepatic veins (≥5 mm), have important clinical implications in liver transplantation and resection. This study aimed to evaluate anatomical variations of the right hepatic vein using quantitative three-dimensional visualization analysis. Computed tomography images of 650 patients were retrospectively analyzed, and three-dimensional visualization was applied using the derived data to analyze large variant right hepatic veins. The proportion of the large variant right hepatic vein was 16.92% (110/650). According to the location and number of the variant right hepatic veins, the configuration of the right hepatic venous system was divided into seven subtypes. The length of the retrohepatic inferior vena cava had a positive correlation with the diameter of the right hepatic vein (rs = 0.266, p = 0.001) and the variant right hepatic veins (rs = 0.211, p = 0.027). The diameter of the right hepatic vein was positively correlated with that of the middle hepatic vein (rs = 0.361, p < 0.001), while it was inversely correlated with that of the variant right hepatic veins (rs = -0.267, p = 0.005). The right hepatic vein diameter was positively correlated with the drainage volume (rs = 0.489, p < 0.001), while the correlation with the variant right hepatic veins drainage volume was negative (rs = -0.460, p < 0.001). The number of the variant right hepatic veins and their relative diameters were positively correlated (p < 0.001). The volume and percentage of the drainage area of the right hepatic vein decreased significantly as the number of the variant right hepatic vein increased (p < 0.001). The findings of this study concerning the variations of the hepatic venous system may be useful for the surgical planning of liver resection or transplantation.

Hepatic venous reconstruction of the left lateral segment with emphasis on anomalous hepatic vein in pediatric liver transplantation

Left lateral segment grafts have become a suitable option in pediatric liver transplantation (PLT). The correlation between hepatic vein (HV) reconstruction and outcome is relevant when assessing the safe use of these grafts. We retrospectively reviewed the medical records prospectively collected from a pediatric living donor liver transplantation database and conducted a comparative analysis of the different left lateral segment graft types according to HV reconstruction. Donor, recipient, and intraoperative variables were analyzed. Post-transplant outcomes included vascular complications such as hepatic vein outflow obstruction, early (≤30 d) and late (>30 d) PVT, hepatic artery thrombosis, and graft survival. From February 2017 to August 2021, 303 PLTs were performed. According to venous anatomy, the distribution of the left lateral segment was as follows: single HV (type I) in 174 (57.4%), close HVs, simple venoplasty for reconstruction (type II) in 97 (32.01%), anomalous hepatic vein (AHV) with a distance between the HVs orifices that allowed simple venoplasty (type IIIA) in 25 (8.26%) and AHV with a distance between the HVs orifices requiring homologous venous graft interposition (type IIIB) in 07 (2.31%) grafts. Type IIIB grafts came from male donors ( p =0.04) and had a higher mean donor height ( p =0.008), a higher mean graft weight, and a higher graft-to-recipient weight ratio, both p =0.002. The median follow-up time was 41.4 months. The overall cumulative graft survival was 96.3%, and comparative graft survival showed no difference (log-rank p =0.61). No hepatic vein outflow obstructions were observed in this cohort study. There was no statistically significant difference in the post-transplant outcomes between the graft types. The venous reconstruction of the AHV with homologous venous graft interposition had similar outcomes in the short and long term.

Venous drainage of the left liver: an evaluation of anatomical variants and their clinical relevance

AIM

To evaluate the variations in venous drainage from the left liver.

MATERIALS AND METHODS

A retrospective evaluation was performed of all consecutive abdominal computed tomography (CT) examinations at a tertiary referral facility between 1 January and 30 June 2018. Osirix (Pixmeo SARL, Bernex, Switzerland) was used to examine the major hepatic veins and their tributaries in each scan. The classification of variants as proposed by Nakamura and Tsuzuki was used to describe the findings. The following information was collected: ramification pattern, number, length and diameter of middle (MHV) and left (LHV) hepatic vein tributaries. Two researchers collected data independently, and the average measurements were used as the final dimensions.

RESULTS

Of 102 examinations evaluated, only 27 demonstrated the conventional venous drainage patterns. The LHV and MHV combined to form a common trunk that emptied into the inferior vena cava (IVC) in 75 (73.5%) cases. The common trunk had a mean length of 8.89 mm and mean diameter of 20.18 mm. Other patterns included Nakamura and Tsuzuki type I (27.5%), type II (29.4%) and type III variants (16.7%). In addition, 4.9% of patients had absent superior middle veins and 80% had supernumerary short hepatic veins (4%).

CONCLUSION

Only 26.5% of patients in this population had conventional venous drainage from the left liver. Surgeons and radiologists in hepatobiliary practice should be aware of these variants in order to minimise morbidity when performing invasive procedures.

Segmentation of liver and vessels from CT images and classification of liver segments for preoperative liver surgical planning in living donor liver transplantation

BACKGROUND AND OBJECTIVE

The present study developed an effective surgical planning method consisting of a liver extraction stage, a vessel extraction stage, and a liver segment classification stage based on abdominal computerized tomography (CT) images.

METHODS

An automatic seed point identification method, customized level set methods, and an automated thresholding method were applied in this study to extraction of the liver, portal vein (PV), and hepatic vein (HV) from CT images. Then, a semi-automatic method was developed to separate PV and HV. Lastly, a local searching method was proposed for identification of PV branches and the nearest neighbor approximation method was applied to classifying liver segments.

RESULTS

Onsite evaluation of liver segmentation provided by the SLIVER07 website showed that the liver segmentation method achieved an average volumetric overlap accuracy of 95.2%. An expert radiologist evaluation of vessel segmentation showed no false positive errors or misconnections between PV and HV in the extracted vessel trees. Clinical evaluation of liver segment classification using 43 CT datasets from two medical centers showed that the proposed method achieved high accuracy in liver graft volumetry (absolute error, AE = 45.2 ± 20.9 ml; percentage of AE, %AE = 6.8% ± 3.2%; percentage of %AE > 10% = 16.3%; percentage of %AE > 20% = none) and the classified segment boundaries agreed with the intraoperative surgical cutting boundaries by visual inspection.

CONCLUSIONS

The method in this study is effective in segmentation of liver and vessels and classification of liver segments and can be applied to preoperative liver surgical planning in living donor liver transplantation.

Portal Supply and Venous Drainage of the Caudate Lobe in the Healthy Human Liver: Virtual Three-Dimensional Computed Tomography Volume Study

OBJECTIVE

The venous vascular anatomy of the caudate lobe is exceptional. The purpose of this study was to assess portal inflow and venous outflow volumes of the caudate lobe.

METHODS

Extrahepatic (provided by the first-order branches) versus intrahepatic (provided by the second- to third-order branches) portal inflow, as well as direct (via Spieghel veins) versus indirect (via hepatic veins) venous drainage patterns were analyzed in virtual 3-D liver maps in 140 potential live liver donors.

RESULTS

The caudate lobe has a greater intrahepatic than extrahepatic portal inflow volume (mean 55 ± 26 vs. 45 ± 26%: p = 0.0763), and a greater extrahepatic than intrahepatic venous drainage (mean 54-61 vs. 39-46%). Intrahepatic drainage based on mean estimated values showed the following distribution: middle > inferior (accessory) > right > left hepatic vein.

CONCLUSIONS

Sacrifice of extrahepatic caudate portal branches can be compensated by the intrahepatic portal supply. The dominant outflow via Spieghel veins and the negligible role of left hepatic vein in caudate venous drainage may suggest reconstruction of caudate outflow via Spieghel veins in instances of extended left hemiliver live donation not inclusive of the middle hepatic vein. The anatomical data and the real implication for living donors must be further verified by clinical studies.

Anatomic Peculiarities of Pig and Human Liver

Many investigations on surgical methods and medical treatment are currently done on pigs. This is possible because the pig is sufficiently close genetically to humans. In recent years, progress in liver surgery has opened new possibilities in surgical treatment of liver diseases. Because the methods are relatively novel, various improvements are still needed, and it is thus helpful to conduct experimental surgeries on pig livers. We reviewed the literature to compare the anatomic and functional features of pig and human livers, information that will be of great importance for improving surgical techniques. During the literature review, we used various sources, such as PubMed, Scopus, and veterinary journals. Our results were summarized in diagrams to facilitate understanding of the vascular structure and biliary systems. We conclude that, although the shapes of the human and pig livers are quite different, the pig liver is divided into the same number of segments as the human liver, which also shows a common structure of the vascular system. Thus, with the anatomic and structural features of the pig liver taken into account, this animal model can be used in experimental hepatic surgery.

Impact of Graft Type in Living Donor Liver Transplantation: Remnant Liver Regeneration and Outcome in Donors

OBJECTIVES

Liver regeneration and donor safety in right-lobe (RL) and left-lobe (LL) grafts are essential for donors in living donor liver transplantation (LDLT). Our aim was to compare the liver regeneration rate and postoperative outcome between different donor graft types in LDLT.

MATERIALS AND METHODS

A total of 95 donors were divided into 2 groups: RL (n = 42) and LL (n = 53). The remnant liver of LL donors were subdivided into 3 subgroups according to the different hepatic venous drainage pattern that dominates from right hepatic vein (dominant RHV; n = 34), middle hepatic vein (dominant MHV; n = 10), and include MHV for left lateral segment (LLS) graft (n = 9). The demographic data, postoperative laboratory data, complications, remnant liver volume (RLV), and remnant liver regeneration rate (RLRR) 6 months after surgery were compared.

RESULTS

The postoperative total bilirubin (TB), prothrombin time (PT), and intensive care unit (ICU) stays of the LL group were lower than the RL group (P < .05). The LL group has no significant better regeneration rate 6 months after surgery than the RL group. However, dominant RHV and LLS groups have significantly better RLRR than the RL group (89.2% vs 86% and 95.1% vs 86%, respectively, P < .05), but no significance in the dominant MHV group.

CONCLUSION

In conclusion, different hepatic venous drainage patterns of remnant liver grafts may affect the regeneration rate in LL LDLT, especially with dominant RHV donors, may have more comparable outcomes with that of RL, and should be a favorable option during donor selection.

Importance Rat Liver Morphology and Vasculature in Surgical Research

BACKGROUND The laboratory rat is one of the most popular experimental models for the experimental surgery of the liver. The objective of this study was to investigate the morphometric parameters, physiological data, differences in configuration of liver lobes, biliary system, and vasculature (arteries, veins, and lymphatic vessels) of the liver in laboratory rats. In addition, this study supports the anatomic literature and identified similarities and differences with human and other mammals. MATERIAL AND METHODS Forty laboratory rats were dissected to prepare corrosion casts of vascular system specimens (n=20), determine the lymph vessels and lymph nodes (n=10), and for macroscopic anatomical dissection (n=10) of the rat liver. The results are listed in percentages. The anatomical nomenclature of the liver morphology, its arteries, veins, lymph nodes, and lymphatic vessels are in accordance with Nomina Anatomica Veterinaria. RESULTS We found many variations in origin, direction, and division of the arterial, venous, and lymphatic systems in rat livers, and found differences in morphometric parameters compared to results reported by other authors. The portal vein was formed by 4 tributaries in 23%, by 3 branches in 64%, and by 2 tributaries in 13%. The liver lymph was drained to the 2 different lymph nodes. The nomenclature and morphological characteristics of the rat liver vary among authors. CONCLUSIONS Our results may be useful for the planing of experimental surgery and for cooperation with other investigation methods to help fight liver diseases in human populations.

Intrahepatic Vascular Anatomy in Rats and Mice--Variations and Surgical Implications

INTRODUCTION

The intra-hepatic vascular anatomy in rodents, its variations and corresponding supplying and draining territories in respect to the lobar structure of the liver have not been described. We performed a detailed anatomical imaging study in rats and mice to allow for further refinement of experimental surgical approaches.

METHODS

LEWIS-Rats and C57Bl/6N-Mice were subjected to ex-vivo imaging using μCT. The image data were used for semi-automated segmentation to extract the hepatic vascular tree as prerequisite for 3D visualization. The underlying vascular anatomy was reconstructed, analysed and used for determining hepatic vascular territories.

RESULTS

The four major liver lobes have their own lobar portal supply and hepatic drainage territories. In contrast, the paracaval liver is supplied by various small branches from right and caudate portal veins and drains directly into the vena cava. Variations in hepatic vascular anatomy were observed in terms of branching pattern and distance of branches to each other. The portal vein anatomy is more variable than the hepatic vein anatomy. Surgically relevant variations were primarily observed in portal venous supply.

CONCLUSIONS

For the first time the key variations of intrahepatic vascular anatomy in mice and rats and their surgical implications were described. We showed that lobar borders of the liver do not always match vascular territorial borders. These findings are of importance for the design of new surgical procedures and for understanding eventual complications following hepatic surgery.

[Application of 3D visualization, 3D printing and 3D laparoscopy in the diagnosis and surgical treatment of hepatic tumors]

OBJECTIVE

To study the value of three-dimensional (3D) visualization, 3D printing and 3D laparoscopy (3-3D techniques) in the diagnosis and surgical treatment of hepatic tumors.

METHODS

From November 2013 to January 2015, 22 patients with hepatic tumors admitted in our department underwent abdominal thin-slice CT scanning. The CT images were imported into Medical Image three Dimensional Visualization System (MI-3DVS) for 3D reconstruction. Standard Template Library (STL) files were exported for 3D printing. The hepatic vascular classification and predicted liver resection were performed with the aid of MI-3DVS system. The 3D models were then printed and virtual liver resections were executed accordingly. Based on these preoperative surgical planning data, we performed anatomical hepatectomy using 3D laparoscopy, and the intraoperative blood loss, volume of virtual and actual liver resection and postoperative hospital stay were recorded.

RESULTS

According to Michels's classifications, 19 patients had type I, 2 had type II, and 1 had type VIII hepatic arteries; based on Cheng classifications, the portal vein was classified into type I in 17 cases, type II in 2 cases, and type III in 2 cases, and type IV in 1 case; according to Nakamura classifications, the right hemiliver hepatic vein was classified into type I in 10 cases, type II in 7 cases, and type III in 5 cases. In the virtual operations, the mean volume of liver resected was 490 ± 228 ml and the mean remnant liver volume was 885 ± 139 ml, with a remnant to functional liver volume ratio of (71 ± 11)%. The 3D printed models stereoscopically displayed the location of the liver tumors and adjacent liver vascular structure clearly. Laparoscopic hepatectomy was performed successfully in 20 patients guided by the 3-3D techniques, and the other 2 patients required convertion to open hepatectomy. The mean operation time was 186 ± 92 min, the intraoperative blood loss was 284 ± 286 ml, the mean actual liver resection volume was 491 ± 192 ml, and the mean postoperative hospital stay of the patients was 8.6 ± 3.7 days.

CONCLUSIONS

The 3-3D technique can facilitate the evaluation of preoperative risk and critical anatomical structures and navigate the surgical procedure in real time in anatomical hepatectomy for hepatic tumors.

The student's dilemma, liver edition: incorporating the sonographer's language into clinical anatomy education

Anatomy students are often confused by multiple names ascribed to the same structure by different clinical disciplines. Increasingly, sonography is being incorporated into clinical anatomical education, but ultrasound textbooks often use names unfamiliar to the anatomist. Confusion is worsened when ultrasound names ascribed to the same structure actually refer to different structures. Consider the sonographic main lobar fissure (MLF). The sonographic MLF is a hyper-echoic landmark used by sonographers of the right upper quadrant. Found in approximately 70% of people, there is little consensus on what the sonographic MLF is anatomically. This structure appears to be related to the main portal fissure (aka principal plane of the liver or principal hepatic fissure), initially described by anatomists and surgeons as in intrahepatic division along the middle hepatic vein which in essence divides the territories of the left and right hepatic arteries and biliary systems. By exploring the relationship between the main portal fissure and the sonographic MLF in cadaveric livers ex vivo, the data suggest the sonographic MLF is actually an extrahepatic structure that parallels the rim of the main portal fissure. The authors recommend that this structure be renamed the "sonographic cystic pedicle," which includes the cystic duct and ensheathing fat and blood vessels. In the context of the redefined underlying anatomy, the absence of the sonographic cystic pedicle due to anatomic variation may serve an important clinical role in predicting complications from difficult laparoscopic cholecystectomies and is deserving of future study.

Contrast-enhanced magnetic resonance angiography for the preoperative evaluation of hepatic vascular anatomy in living liver donors: a meta-analysis

RATIONALE AND OBJECTIVES

The objective of this study was to determine the diagnostic accuracy of contrast-enhanced magnetic resonance angiography (MRA) when used in the preoperative evaluation of hepatic vascular anatomy in living liver donors.

MATERIALS AND METHODS

A computer-assisted literature searching of EMBASE, PubMed (MEDLINE), and the Cochrane library databases was conducted to identify potentially relevant articles which primarily examined the utility of contrast-enhanced MRA in the preoperative evaluation of hepatic vascular anatomy in living liver donors. We used the Q statistic of chi-squared value test and inconsistency index (I-squared, I(2)) to estimate the heterogeneity of the data extracted from all selected studies. Meta-Disc software (version 1.4) (ftp://ftp.hrc.es/pub/programas/metadisc/Metadisc_update.htm) was used to perform our analysis.

RESULTS

Eight studies were included in the present meta-analysis. A total of 289 living liver donor candidates and 198 patients who underwent liver harvesting were included in the present study. The pooled sensitivities of hepatic artery (HA), portal vein (PV), and hepatic vein (HV) in this meta-analysis were 0.84, 0.97, and 0.94, respectively. The pooled specificities of HA, PV, and HV were 1.00, 1.00, and 1.00, respectively. The pooled diagnostic odds ratios of HA, PV, and HV were 127.28, 302.80, and 256.59, respectively. The area under the summary receiver-operating characteristic curves of HA, PV, and HV were 0.9917, 0.9960, and 0.9813, respectively.

CONCLUSIONS

The high sensitivity and specificity demonstrated in this meta-analysis suggest that contrast-enhanced MRA was a promising test for the preoperative evaluation of hepatic vascular anatomy in living liver donors.

[Three-dimensional reconstruction of individual hepatic veins and portal veins system in hepatectomy]

OBJECTIVE

To study the imaging characteristics and variations of individual digitized hepatic vein and portal vein which were reconstructed by medical image three-dimensional visualization system (MI-3DVS), assess the value of MI-3DVS assisted hepatectomy.

METHODS

From June 2008 to September 2012, the clinical data of 81 patients who underwent hepatectomy with the assist of MI-3DVS were retrospectively reviewed. There were 61 male and 20 female patients, and their age were 12-81 years (median 46 years). The patients with malignant tumors were in 69 cases and with benign tumors in 12 cases. The characteristics and variations of individual digitized hepatic vein and portal vein were observed.Omnidirectional rotation of the three-dimensional (3D) model to observe the distribution of intrahepatic venous system as well as the relationship between the tumor and the veins. 3D models were then simulated resection by the Freeform modeling system.

RESULTS

Of all the 81 3D models of the patients, greater posterior hepatic veins appeared in 10 (12.3%) cases, segment VI hepatic vein appeared in 34 (41.9%) cases. The portal vein was separted with the left branch and the right branch in the hilar in 64 cases, the portal trunk was divided into the left branch of portal vein, the right anterior portal branches, the right posterior portal branches trifurcated in 10 cases, the branch of right anterior portal vein start from the left trunk and the branch of right posterior portal vein start from the main trunk independently in 6 cases, there was 1 case, lack of left branch of portal vein. 81 patients underwent hepatectomy with the assist of MI-3DVS, minor hepatectomy in 57 cases, major hepatectomy in 24 cases (comparatively-reduced major hepatectomy in 12 cases). R0-resection was achieved in all of the patients. Both the inflow and the outflow were maintained in the residual liver after the completion of hepatectomy. Postoperative liver failure was observed in none of the patients.

CONCLUSIONS

MI-3DVS in liver resection was the best choice of surgical approach provides an intuitive basis, and it could reduce the risk of surgery to prevent postoperative hepatic failure.

Three-dimensional in vivo imaging of the murine liver: a micro-computed tomography-based anatomical study

Various murine models are currently used to study acute and chronic pathological processes of the liver, and the efficacy of novel therapeutic regimens. The increasing availability of high-resolution small animal imaging modalities presents researchers with the opportunity to precisely identify and describe pathological processes of the liver. To meet the demands, the objective of this study was to provide a three-dimensional illustration of the macroscopic anatomical location of the murine liver lobes and hepatic vessels using small animal imaging modalities. We analysed micro-CT images of the murine liver by integrating additional information from the published literature to develop comprehensive illustrations of the macroscopic anatomical features of the murine liver and hepatic vasculature. As a result, we provide updated three-dimensional illustrations of the macroscopic anatomy of the murine liver and hepatic vessels using micro-CT. The information presented here provides researchers working in the field of experimental liver disease with a comprehensive, easily accessable overview of the macroscopic anatomy of the murine liver.

Extraction of liver vessel centerlines under guidance of patient-specific models

Fast extraction of blood vessels of abdominal organs is still a challenging task especially in intra-procedural treatments due to large tissue deformation. In this study, we propose a novel joint vessel extraction and registration framework. This vessel extraction technique is under the guidance of prior knowledge patient specific models. The proposed technique automatically provides correspondence between extracted vessels and pre-procedural vessels, which is important for image guidance such as labeled vessels from pre-procedural models, improves the quality of disease diagnosis using multiple images and follow-up, and provides important information for nonrigid image registration. Another key component in our framework is to dynamically update mapped pre-procedural models by rapidly registering the patient model to the current image based on strain energy, point marks and 3D extracted vessels currently available. We have demonstrated the effectiveness of our technique in extraction of vessels from liver MR images. Validation shows a extraction error of 3.99 mm. This technique has the potential to significantly improve the quality of intra-procedural image guidance, diagnosis of disease and treatment planning.

Anatomy of the retrohepatic segment of the inferior vena cava and the ostia venae hepaticae with its clinical significance

PURPOSE

The present study was undertaken to provide morphological data regarding the retrohepatic segment of the inferior vena cava (RHIVC) and ostia venae hepaticae with an emphasis on the clinical significance of the observations made.

METHODS

This was an observational study conducted on 160 apparently healthy, randomly selected, cadaveric adult human livers fixed in 10% formalin. The distribution of the hepatic venous openings was studied by dividing the interior of the RHIVC into 16 quadrants. These openings were classified as large, medium, small and very small openings based on their diameter and were also classified as single/double/triple/quadruple according to the number of veins opening into them.

RESULTS

The median length of RHIVC was 7.3 cm (6.2-8.4) and was directed obliquely with respect to the vertical axis of the liver in 92.5% of cases. A total of 1,376 ostia venae hepaticae were observed, and the median number of openings per liver was 7 (5-9). The right hepatic vein had a single opening in 156 (97.5%) and the left and middle hepatic veins had a common opening in 144 (90%) cases. A longitudinal area on the anterior wall of the RHIVC, to the right side of the midline, was relatively avascular with 10.1% of the venous openings, of which 70% were single openings of the right dorsal vein having a small diameter (0.1-0.5 cm).

CONCLUSION

During liver hanging maneuver, rightward direction of the dissecting forceps would avoid injury to the caudate vein and allow access to the safe avascular space in the RHIVC.

[Non-contrast-enhanced MR angiography for selective visualization of the hepatic vein]

OBJECTIVE

To evaluate the diagnostic performance of non-contrast-enhanced MR angiography (NCE-MRA) in the preoperative assessment of hepatic vein.

MATERIALS AND METHODS

Contrast-enhanced MR angiography (CE-MRA)and NCE-MRA were performed on ten patients with hepatic cirrhosis and twelve potential living liver donors with the same 1. 5T MR scanner. The anatomic angiographic images were reconstructed and reviewed by two radiologists independently. The quality of the images of hepatic vein vessels was rated with a four point scale.

RESULTS

After consensus reading, 19 NCE-MRA images (86.4%) and 20 CE-MRA images (90.9%) scored more than 3 point, respectively. The segmental branch vessels were visualized on MR angiography in the majority of cases. Both NCE-MRA and CE-MRA correctly characterized 20 out of 22 hepatic veins without false positive reporting. The NCE-MRA reported two false negative cases. There were no statistically significant differences between NCE-MRA and CE-MRA for the characterization of hepatic vasculature (P > 0.05). High consistency was achieved between the two reviewers, with Kappa values over 0.75.

CONCLUSION

NCE-MRA is a non-invasive and effective method for the comprehensive assessment of hepatic vein.

Detailed dissection of hepato-caval junction and suprarenal inferior vena cava

BACKGROUND/AIMS

There are few anatomical studies on hepatic vein compared to hepatic artery and portal vein. The aim of this study is to clarify the branching patterns of hepatic veins, supra and infra-diaphragmatic course of suprarenal inferior vena cava and its relation with the liver.

METHODOLOGY

Between March and May 2008, 103 consecutive autopsy examinations were included in the study. Hepatic vein anatomy was classified according to the Broelsch classification. The anatomic relations of supra-diaphragmatic and infra-diaphragmatic (suprarenal) inferior vena cava were revealed.

RESULTS

Majority of subjects have Type a (42.7%) variation. The inferior right hepatic vein was presented alone in 26 and together with middle right hepatic vein in 15 subjects. Most of the phrenic veins were drained to the right-anterior sidewall of inferior vena cava (n=21/25 above the diaphragm and, n=144/306 below the diaphragm). Drainage of the right adrenal vein directly into the right side of the inferior vena cava was found in 82 subjects (80%). Most of subjects had 2 lumbar branches in the posterior sidewall of infradiaphragmatic inferior vena cava (n=92/103).

CONCLUSIONS

The proposed classification of hepatic veins and obtained anatomical details from this study provides useful assistance for hepatic surgeons in phases of operative planning and vascular control maneuvers required in liver surgery.

Efficacy of CT angiography for preoperative vascular mapping in adult to adult living related liver transplant donors

OBJECTIVE

To assess the utility of CT angiography (CTA) in preoperative mapping of hepatic vascular anatomy in adult-to-adult living related liver transplant (LRLT) donors.

MATERIAL AND METHOD

Over a 3-year period, 32 potential LRLTdonors underwent CTA with subsequent comparison studies [digital subtraction angiography (DSA) and/or transplantation] were included in this study. Their CTA reports were retrospectively correlated with available DSA and/or operative findings.

RESULTS

CTA correctly predicted right lobe arterial and portal venous anatomy in 32/32 (100%) donors. In 27 donors, hepatic venous anatomy on CT was compared with operative findings. The hepatic veins were well opacified in 23/27 (85.2%) donors. Of these, 15/16 (93.8%) significant (> or =5 mm) accessory right hepatic veins and 11/11 (100%) significant segment VIII vein draining to middle hepatic vein were detected.

CONCLUSION

CTA provided an excellent preoperative depiction of hepatic vascular anatomy in LRLT donors.

Multiscale model of liver DCE-MRI towards a better understanding of tumor complexity

The use of quantitative imaging for the characterization of hepatic tumors in magnetic resonance imaging (MRI) can improve the diagnosis and therefore the treatment of these life-threatening tumors. However, image parameters remain difficult to interpret because they result from a mixture of complex processes related to pathophysiology and to acquisition. These processes occur at variable spatial and temporal scales. We propose a multiscale model of liver dynamic contrast-enhanced (DCE) MRI in order to better understand the tumor complexity in images. Our design couples a model of the organ (tissue and vasculature) with a model of the image acquisition. At the macroscopic scale, vascular trees take a prominent place. Regarding the formation of MRI images, we propose a distributed model of parenchymal biodistribution of extracellular contrast agents. Model parameters can be adapted to simulate the tumor development. The sensitivity of the multiscale model of liver DCE-MRI was studied through observations of the influence of two physiological parameters involved in carcinogenesis (arterial flow and capillary permeability) on its outputs (MRI images at arterial and portal phases). Finally, images were simulated for a set of parameters corresponding to the five stages of hepatocarcinogenesis (from regenerative nodules to poorly differentiated HepatoCellular Carcinoma).

Risk analysis for intraoperative liver surgery

Hepatic vessel structure is very important to ensure the blood supply of the liver tissue. Therefore the knowledge of the hepatic vessel system is indispensable in liver surgery planning, for example before performing a liver resection. The purpose of this paper is to present an easy to use and fast method concerning hepatic vessel segmentation and risk analysis, which is intended to be applicable in clinical routine.

Anatomy of retrohepatic segment of inferior vena cava and termination of hepatic veins

BACKGROUND

Information on anatomy of intrahepatic inferior vena cava (IVC) and hepatic vein openings in it is limited.

METHODS

We studied the retrohepatic segment of IVC and hepatic vein openings in it in 69 livers obtained from cadavers. The retrohepatic portion of the IVC was opened posteriorly by a vertical cut, the exposed surface was divided into 12 quadrants and the position, size, and septation of ostia of hepatic veins and any accessory openings were charted; measurements were made using Vernier calipers.

RESULTS

The median length of the intrahepatic IVC was 5.7 (range 3.3-8.2) cm and its median diameter was 2.3 (range 1.5-3.0) cm. The superior (major) set of hepatic veins comprised of two veins (right and left-middle) in 45 (65%) cases, three veins (right, middle, and left) in 23 (33%) and four veins in one (2%) case. Median diameter of the right hepatic vein was 1.5 (range 0.8-2.7) cm and that of left hepatic vein was 1.2 (0.7-2.6) cm. Middle hepatic vein, when separate, had a median diameter of 1.1 (range 0.5-1.5) cm. The inferior (minor) set of hepatic veins had two to 16 (median 7) veins.

CONCLUSIONS

Our data provide information on number, size, position, and septation of hepatic vein openings into the IVC. This information may be useful to hepatologists, hepatic surgeons while planning segmental resection of the liver, and to radiologists planning diagnostic and interventional procedures on hepatic venous system.

The use of a projection method to simplify portal and hepatic vein segmentation in liver anatomy

In living donor liver transplantation, the volume of the potential graft must be measured to ensure sufficient liver function after surgery. Couinaud divided the liver into 8 functionally independent segments. However, this method is not simple to perform in 3D space directly. Thus, we propose a rapid method to segment the liver based on the hepatic vessel tree. The most important step of this method is vascular projection. By carefully selecting a projection plane, a 3D point can be fixed in the projection plane. This greatly helps in rapid classification. This method was validated by applying it to a 3D liver depicted on CT images, and the result was in good agreement with Couinaud's classification.

Accessory sulci of the liver. An anatomical study with clinical implications

OBJECTIVE

To study the presence of accessory sulcus (AS) in the embalmed cadaveric livers, and compare it with the normal liver.

METHODS

The present study was conducted on 40 embalmed cadaveric livers in the Department of Anatomy, National University of Malaysia, Kuala Lumpur, Malaysia, from September to October 2007, in order to observe the presence and pattern of anomalous AS.

RESULTS

Out of the 40 liver specimens studied, we observed the presence of AS in only 2 specimens 5%. The AS was located in the inferior and posterior surfaces of the right lobes in 2 specimens.

CONCLUSION

The AS of the liver is a rare anomaly. Research studies had mainly described the diaphragmatic sulci in the liver, however there are no research reports on the presence of AS in the inferior surface of the right lobe of the liver. The presence of the AS may represent the deep course of the hepatic veins superficially, thus proving to be more beneficial to the hepatobiliary surgeons. The AS may be due to a developmental defect, or may be acquired as a result of pressure by any superficial structure. The precise anatomical knowledge of the AS may also be important for radiologists interpreting CT images of injected veins. The gross anatomical findings of anomalous AS in 2 liver specimens, and its clinical implications are being highlighted in the present study.

Clinical significance of detailed preoperative evaluation on donors in right lobe living donor liver transplantation

BACKGROUND/AIMS

To investigate the clinical importance of detailed preoperative evaluation on donors of right lobe graft in living donor liver transplantation.

METHODOLOGY

Between January 2001 and August 2006, 106 potential donors were screened and evaluated. Evaluation focused on imaging study of hepatic vascular system, bile duct system, hepatic volumety and hepatic steatosis.

RESULTS

A total of 81 women (77.88%) and 23 men (22.12%) were evaluated with 51 donors participating. 55 potential donors were rejected. One donor failed to complete donation hepatectomy due to 40% macrovesicular steatosis found during operation. Variation of portal vein and hepatic artery could be found with evaluation. However, variations of hepatic veins especially the tributaries of middle hepatic vein and right hepatic bile duct showed on CT scan were not concordant with those at the cut surface of the liver graft. All the 50 right lobe grafts did not include middle hepatic vein, weighing 400-850 g (media 550 g), accounting for 31.74-71.68% (mean 45.35%) of standard liver volume (SLV) of the recipients. Donor morbidity, including all complications, was 8% with no mortality. All the donors recovered uneventfully.

CONCLUSIONS

Detailed evaluation for hepatic lobar volume, vascular anatomy, virtual resection planes and morphologic features is of clinical importance in the selection of suitable donor in living right liver transplantation.

[Anatomy of the liver: what you need to know]

A precise knowledge of arterial, portal, hepatic and biliary anatomical variations is mandatory when a liver intervention is planned. However, only certain variations must be searched when a precise intervention is planned. The basic liver anatomy as well as the most relevant malformations will be precised.

An artificial vascular graft is a useful interpositional material for drainage of the right anterior section in living donor liver transplantation

Congestion in the anterior section in a right liver (RL) without a middle hepatic vein (MHV) may lead to graft dysfunction. To solve this problem, an RL draining MHV branches with autologous or cryopreserved vessels can be introduced. However, these vessels are often unavailable, and their preparation is time-consuming. An expanded polytetrafluoroethylene (ePTFE) graft may be used for anterior section drainage. Between February and November 2005, 26 recipients underwent RL liver transplantation draining MHV branches with an ePTFE graft (group P). Twenty-six ePTFE grafts (6 or 7 mm in internal diameter) drained 35 MHV branches on the back table to the graft right hepatic vein or to the recipient's inferior vena cava. The patency of the ePTFE graft was checked with computed tomography scans of the liver. The outcome of group P was compared with those of an RL group with MHV (group M, n=17) and an RL group without reconstruction of MHV or its tributaries (group R, n=85). The 1-month and 4-month patency rates (PRs) of the ePTFE grafts were 80.8% (21/26) and 38.5% (10/26). All showing early obstruction of the ePTFE graft had congestion in the anterior section, but all showing late obstruction were asymptomatic. The 1-month PRs of group P were comparable to, but the 4-month PRs were lower than, those of group M (both 94.1%; P<0.05). However, 1-year patient and graft survival rates of group P (both 100%) were comparable to those of group M (94.1% and 100%) and better than those of group R (83.5% and 88.2%; P<0.05). In conclusion, the early PR of group P was good, and late obstruction of the ePTFE graft had no impact on congestion in the anterior section or patient survival. Therefore, an ePTFE graft may be a useful interposition material for anterior section drainage in RL transplantation without serious complications.

Surgical anatomy of the liver, hepatic vasculature and bile ducts in the rat

BACKGROUND

The rat is the most used experimental model in surgical research. Virtually all procedures in clinical liver surgery can be performed in the rat. However, the use of the rat model in liver surgery is limited by its small size and limited knowledge of the liver anatomy. As in humans, the rat liver vasculature and biliary system have many anatomical variations. The development of surgical techniques, and the study of liver function and diseases require detailed knowledge of the regional anatomy.

AIM

The objective of this study was to describe and illustrate systematically the surgical anatomy of the rat liver to facilitate the planning and performance of studies in this animal. Knowledge of the diameter and length of liver vessels is also important for the selection of catheters and perivascular devices.

METHODS

Twelve Wistar rat livers were dissected using a surgical microscope. Hepatic and extrahepatic anatomical structures were measured under magnification with a millimeter scale.

CONCLUSION

In this study, we describe the rat liver topographical anatomy, compare it with the human liver and review the literature. Increased knowledge of the rat liver anatomy and microsurgical skills permit individualized dissection, parenchymal section, embolization and ligature of vascular and biliary branches.

Living related liver transplantation: preoperative magnetic resonance imaging for assessment of hepatic vasculature of donor candidates

PURPOSE

To evaluate the accuracy of magnetic resonance angiography (MRA) for preoperative assessment of hepatic vascular anatomy in liver donors before living related liver transplantation.

MATERIAL AND METHODS

A total of 55 consecutive living liver donors (mean age 42 years, range 18-68 years) underwent multiphase contrast-enhanced MRA of the hepatic vessels. Two readers categorized vessel visualization on a five-point scale and recorded vascular anatomy or variations thereof for the arterial, portal venous and venous systems. All 55 living liver donors subsequently underwent right hemihepatectomy for hemiliver donation, and preoperative MRA results were correlated with surgical findings.

RESULTS

Overall vessel visualization assessment demonstrated good or very good ratings for the majority of patients. For hepatic arteries, the mean score was 4.4+/-0.8 (mean+/-standard deviation), and for the portal venous and venous systems it was 4.6+/-0.7 and 4.3+/-0.8, respectively. Among all 55 donors, 16 (29%) demonstrated accessory or replaced hepatic arteries, and seven (13%) and 20 (36%) donors had surgically relevant portal vein (trifurcation or early right posterolateral branching types) and hepatic vein variations, respectively. Correlation coefficients between MRA and surgery were 0.94, 1.00 and 0.91 for hepatic arteries, portal veins and hepatic veins, respectively.

CONCLUSION

In the preoperative evaluation before living related liver donation, contrast-enhanced MR angiography was a highly accurate, noninvasive tool for visualizing the hepatic vasculature and variations thereof in liver donor candidates.

Right inferior phrenic vein indicating the right hepatic vein confluence into the inferior vena cava

BACKGROUND

Limiting backflow bleeding from the hepatic veins is a priority when performing hepatectomy. However, hepatic vein encirclement is difficult, especially in re-resection. We verified the presence and trajectory of the right inferior phrenic vein (RIPV), which could be a useful anatomic landmark to guide surgeons in targeting the extrahepatic right hepatic vein (RHV) before dissection.

METHODS

Between May 2001 and January 2005, 100 consecutive patients with liver tumors were enrolled and underwent hepatectomy: 77 patients underwent surgery for tumors located in the right hemiliver.

RESULTS

RIPV was detected in all but 1 patient (99%), and its trajectory was always guided toward the extrahepatic RHV. The only patient in whom RIPV was not detected had undergone prior liver resection and interstitial therapies for colorectal cancer liver metastases.

CONCLUSIONS

Apart from exceptional conditions, detection of the RIPV is always feasible and allows safe surgical dissection while approaching the extrahepatic RHV before hepatic resection.

Feasibility assessment for tailoring preservation of segment VIII hepatic vein during left liver graft procurement

BACKGROUND/AIMS

Procurement of left lobe (LL) graft occasionally induces large-sized hepatic venous congestion (HVC) at the remnant right liver. Isolated preservation of segment VIII vein (V8) could reduce this HVC, but it has been applied to only a small number of living donor operations to date.

METHODOLOGY

We investigated the indication of tailoring V8 preservation through the anatomical analyses and computer simulation in a large-volume donor pool. After setting up its surgical technique in 3 donor cases, we analyzed the liver anatomy of 147 LL graft donors.

RESULTS

We regarded the first anatomical condition as direct convergence of a large V8 branch on middle hepatic vein root, by which 27 livers were selected. The second was absence of complex hepatic vein branching at the graft cutting line, and 4 livers were excluded. The third was relatively large-sized HVC more than 35% of right lobe volume, and 11 livers were additionally excluded. Finally, 12 (8.2%) of 147 were left after 3-step selection processes. V8 preservation was estimated to reduce the total amount of HVC by 40%.

CONCLUSIONS

We think that tailoring V8 preservation seems to be indicated for 8.2% of LL graft donor livers according to the 3 anatomical conditions.

Tailoring transection of segment V vein for optimal sharing of middle hepatic vein in right-lobe living donor liver transplantation

BACKGROUND/AIMS

Separate reconstruction of multiple V5s (segment V hepatic vein) often resulted in incomplete resolution of hepatic venous congestion (HVC) in the right lobe (RL) grafts. This study intended to obtain single large V5 orifice suitable for middle hepatic vein (MHV) reconstruction.

METHODOLOGY

We tried tailoring V5 transection in 3 of 39 RL donors, in whom MHV anatomy would reveal multiple sizable V5 orifices along the classical transection plane. During transection of its ventral half, the liver cut surface was intentionally deviated leftward to obtain single large V5 orifice with small sacrifice of the medial segment.

RESULTS

Single V5 and single segment VIII vein were reconstructed with interposition vessel graft. Its final shape resembled the combination of RL graft with MHV trunk at the ventral half and RL graft with MHV reconstruction at the dorsal half. There was no noticeable perfusion defect on follow-up computed tomography of all donor and recipient livers.

CONCLUSIONS

We think that this combination of tailoring V5 transection and interposition graft is fully suggestive of the feasibility of modified extended RL graft in donor livers with variant peripheral MHV branching.

Anatomy of the middle hepatic vein: applications to living donor liver transplantation

BACKGROUND/AIMS

In living donor liver transplantation, right lobe graft without a middle hepatic vein (MHV) results in potential venous congestion in the anterior segment, while transplantation with MHV represents an important ethical issue from the perspective of donor safety. The present study assessed ramification patterns of the MHV and relationships between hepatic venous drainage of the anterior and medial segments, to plan optimal harvesting of the right lobe as a graft.

METHODOLOGY

The authors reviewed 102 patients with normal livers who underwent contrast-enhanced multi-detector row CT.

RESULTS

The hepatic vein that drained S4sup (V4sup) joined only the left hepatic vein (LHV) in 60 patients (58%), only the MHV in 25 (25%), and both LHV and MHV in 17 (17%). Both V4sup and the hepatic vein that drained S8 (V8) joined the MHV in 42 patients (42%), and V8 joined proximal to V4sup in 18 of these 42 patients.

CONCLUSIONS

In donation of a right lobe graft including MHV, preservation of V4sup in the remnant donor liver seems possible in most donors.

Volumetric analyses of venous variations in the left liver using 3D-CT venography

BACKGROUND/AIMS

Knowledge of intrahepatic vascular variations, especially in hepatic venous anatomy, is inevitable for carrying out liver surgery safely. However, vascular anatomy of the right liver or right side tributaries of the MHV has been focused in various studies and there have been only a few reports on the left liver.

METHODOLOGY

Sixty consecutive living donors for liver transplantation in a single institute were reviewed. Ramification patterns and drainage volume of each venous tributary were evaluated using 3D-CT venography.

RESULTS

Four characteristic venous tributaries; left superficial vein (LSV), umbilical fissure vein (UFV), and superior/inferior veins of Segment IV (V4sup/4inf) were detected on 3D-CT. Of these, LSV and UFV were sometimes rather thick overwhelming the LHV trunk and drained more than 20% of the left liver in 11 (18.3%) and 4 patients (6.7%), respectively. In such cases, proportions of Segment II (LSV drainage area) or Segment III+IV (UFV drainage area) were significantly large compared with those in typical venous ramification cases.

CONCLUSIONS

Clinically significant findings on venous variations in the left liver were described. Preoperative volumetric assessment of the draining areas of these veins is useful in surgical decision making on venous reconstruction and/or extent of liver resection.

Preoperative evaluation of hepatic arterial and portal venous anatomy using the time resolved echo-shared MR angiographic technique in living liver donors

The purpose of this study was to determine whether MR angiography utilizing the time resolved echo-shared angiographic technique (TREAT) can provide an effective assessment of the hepatic artery (HA) and portal vein (PV) in living donor candidates. MR angiography (MRA)was performed in 27 patients (23 men and 4 women; mean age, 31 years) by using TREAT. Two blinded radiologists evaluated HA anatomy, origin of segment IV feeding artery and PV anatomy in consensus. Qualitative evaluations of MRA images were performed using the following criteria: (a) overall image quality, (b) presence of artifacts, and (c) degree of venous contamination of the arterial phase. Using intraoperative findings as a standard of reference, the accuracy for the HA anatomy, origin of segment IV feeding artery and PV anatomy on TREAT-MRA were 93% (25/27), 85% (23/27), and 96% (26/27), respectively. Overall image qualities were as follows: excellent (n=22, 81%), good (n=4, 15%), and fair (n=1, 4%). Significant artifacts or venous contamination of the arterial phase images was not noted in any patient. TREAT-MRA can provide a complete evaluation of HA and PV anatomy during preoperative evaluation of living liver donors. Furthermore, it provides a more detailed anatomy of the HA without venous contamination.

Anatomical basis for clamping of the right hepatic vein outside the liver during right hepatectomy

The possibility and value of clamping the right hepatic vein (HV) outside the liver during right hepatectomy remain a matter of debate. We carried out an anatomical study on ten fresh cadaveric subjects with no abdominal scarring or hepatic lesions, to determine the biometry of the extraparenchymatous segment of the right HV. One or several accessory right HVs were found in 90% of cases on release of the right edge of the inferior vena cava (IVC). These accessory right HVs had a diameter greater than that of the superior right HV in 10% of cases. In 70% of cases, the extraparenchymatous segment of the vein was free of collateral branches, and in 30% of cases, it was joined by a branch close to its point of exit from the hepatic parenchyma. The length of the vein that can be clamped (length between the point of exit from the hepatic parenchyma and the point of entry of the right HV into the IVC) was 8.6 +/- 1.8 mm (6-12). The right HV entered the vena cava, at an acute angle, in 100% of cases. Clamping of the right HV was possible in all cases. Knowledge of these anatomical points makes it possible to isolate an extraparenchymatous segment of the right HV more safely. The right HV can be isolated and clamped outside the liver in more than 80% of cases, making it possible to carry out right hepatectomy on an exsanguinous liver.

Marginal hepatectomy in the rat: from anatomy to surgery

OBJECTIVE

Based on the 3-dimensional visualization of vascular supply and drainage, a vessel-oriented resection technique was optimized. The new surgical technique was used to determine the maximal reduction in liver mass enabling a 50% 1-week survival rate.

BACKGROUND DATA

Determination of the minimal liver mass is necessary in clinical as well as in experimental liver surgery. In rats, survival seems to depend on the surgical technique applied. Extended hepatectomy with removal of 90% of the liver mass was long regarded as a lethal model. Introduction of a vessel-oriented approach enabled long-term survival in this model.

METHODS

The lobar and vascular anatomy of rat livers was visualized by plastination of the whole organ, respectively, by corrosion casts of the portal vein, hepatic artery and liver veins. The three-dimensional models were used to extract the underlying anatomic structure. In 90% partial hepatectomy, the liver parenchyma was clamped close to the base of the respective liver lobes (left lateral, median and right, liver lobe). Piercing sutures were placed through the liver parenchyma, so that the stem of portal vein and the accompanying hepatic artery but also the hepatic vein were included.

RESULTS

A 1-week survival rate of 100% was achieved after 90% hepatectomy. Extending the procedure to 95% resection by additional removal of the upper caudate lobe led to a 1-week survival rate of 66%; 97% partial hepatectomy, accomplished by additional resection of the lower caudate lobe only leaving the paracaval parts of the liver behind, resulted in 100% lethality within 4 days.

CONCLUSIONS

Using a anatomically based, vessel-oriented, parenchyma-preserving surgical technique in 95% liver resections led to long-term survival. This represents the maximal reduction of liver mass compatible with survival.

The influence of accessory right inferior hepatic veins on the venous drainage in right graft living donor liver transplantation

BACKGROUND/AIMS

Proper venous outflow reconstruction is essential for the success of living donor liver transplantation (LDLT). It has also a decisive impact on postoperative graft dysfunction. The accessory right inferior hepatic veins (IHVs) usually drain parts of the lateral sector of the right hemiliver graft (RHL). The purpose of our study was to: (1) evaluate the drainage patterns of the IHVs in right hemiliver grafts; (2) analyze the influence of IHVs on the dominance relationships between the right and middle hepatic veins in RHL's; (3) evaluate some potential correlation between drainage patterns of IHVs and the portal vein anatomy.

METHODOLOGY

We analyzed 3-dimensional CT-imaging reconstructions of 71 potential live liver donors evaluated at our Institution between January 2003 and October 2004.

RESULTS

(1) Thirty-six (51%) donors had inferior hepatic veins (IHV) with detectable venous drainage territories, (2) the RHV/IHV-complex was dominant in 97% of cases, and the RHV as a single veinwithout anatomical IHV was dominant in 94% of right hemiliver grafts, (3) 27 of 71 livers (38%) showed a central (n=11) or peripheral (n=16) PV anomaly, (4) IHV provided a mean 32% of venous drainage in the right lateral sector, and in some cases drained up to 25% of the right medial sector irrespective of the PV anatomy, (5) such cases required IHV reconstruction to prevent severe tissue congestion in the right hemiliver graft.

CONCLUSIONS

Accurate insight into the drainage patterns of the right and middle hepatic veins and precise knowledge of the functional volume drained by the IHV are essential when planning for the proper outflow reconstruction of right hemiliver grafts in LDLT.

Gross anatomy of the retrohepatic segment of the inferior vena cava in northwest Indians

BACKGROUND AND OBJECTIVES

Information regarding the size and position of the ostia of veins opening into the retrohepatic segment of inferior vena cava (HIVC) in northwest Indians is not available. Knowledge of gross anatomy of this segment is of importance in cases of segmental resection of the liver involving the groove for inferior vena cava (IVC) and when performing selective hepatic venography. We carried out this study to provide information on gross anatomy of HIVC in northwest Indians.

METHODS

Livers were obtained from 500 adult autopsy subjects. The HIVC was opened posteriorly by a vertical cut and its circumference at the upper and lower cut ends was measured. To study the position of the ostia of the hepatic veins, HIVC was divided transversely into upper, middle and lower thirds. The anterior and anterolateral walls of HIVC were also divided into four equal parts longitudinally. The venous ostia were classified according to the size of their openings. In addition, in 100 livers the openings were injected with a 20 per cent solution of cellulose acetate butyrate (CAB) in acetone and veins were dissected.

RESULTS

The HIVC extended upwards and to the left either obliquely (66.4%) or by describing a gentle curve (33.6%) in its upper half or upper third. Its average length was about 71 mm. Mean diameter at the upper cut end was about 19 mm. The posterior aspect of the upper half or upper one third of HIVC was covered by an extension of the caudate lobe completely (4%) or incompletely (7.4%). The ostia of the left, middle and right hepatic veins were large (>10 mm) and were located in the upper third segment of HIVC. In 87 per cent of specimens the left and middle hepatic veins had a common opening on the left anterior area. The ostium of the right hepatic vein was present in the right anterior area.

INTERPRETATION AND CONCLUSION

In conclusion, our study provided gross measurements of HIVC in northwest Indians. A knowledge of the anatomy of HIVC and hepatic venous ostia will help the clinician interventional operator in planning the treatment by choosing a balloon of correct size and at correct site. The measurements helps in determining the fall in portal pressure with pharmacotherapy given for the prevention of variceal bleed.

Branching patterns and drainage territories of the middle hepatic vein in computer-simulated right living-donor hepatectomies

Full right hepatic grafts are most frequently used for adult-to-adult living donor liver transplantation (LDLT). One of the major problems is venous drainage of segments 5 and 8. Thus, this study was designed to provide information on venous drainage of right liver lobes for operation-planning. Fifty-six CT data sets from routine clinical imaging were evaluated retrospectively using a liver operation-planning system. We defined and analyzed venous drainage segments and the impact of anatomic variations of the middle hepatic vein (MHV) on venous outflow from segments 5 and 8. MHV variations led to significant shifts of segment 5 drainage between the middle and right hepatic vein. In cases with the most frequent MHV branching pattern (n = 33), a virtual hepatectomy closely right to the MHV intersected drainage vessels that provided drainage for 30% of the potential graft, not taking into account potential veno-venous shunts. In individuals with inferior MHV branches that extend far into segments 5 and 6 (n = 10), the overall graft volume at risk of impaired venous drainage increased by 5% (p < 0.001). If this is confirmed in clinical trials and correlated with intraoperative findings, the use of liver operation-planning systems would be beneficial to improve overall outcome after right lobe LDLT.

Transjugular liver biopsy: prospective evaluation of the angle formed between the hepatic veins and the vena cava main axis and modification of a semi-automated biopsy device in cases of an unfavorable angle

In cases of transjugular liver biopsies, the venous angle formed between the chosen hepatic vein and the vena cava main axis in a frontal plane can be large, leading to technical difficulties. In a prospective study including 139 consecutive patients who underwent transjugular liver biopsy using the Quick-Core biopsy set, the mean venous angle was equal to 49.6 degrees. For 21.1% of the patients, two attempts at hepatic venous catheterization failed because the venous angle was too large, with a mean of 69.7 degrees. In all of these patients, manual reshaping of the distal curvature of the stiffening metallic cannula, by forming a new mean angle equal to 48 degrees , allowed successful completion of the procedure in less than 10 min.

Modified techniques for adult-to-adult living donor liver transplantation

BACKGROUND

Because of critical organ shortage, transplant professionals have utilized living donor liver transplantation (LDLT) in recent years. We summarized our experience in adult-to- adult LDLT with grafts of right liver lobe by a modified technique.

METHODS

From January 2002 to August 2005, 24 adult patients underwent living donor liver transplantation with grafts of the right liver lobe at West China Hospital, Sichuan University, China. Twenty-two patients underwent modified procedures designed to improve the reconstruction of the right hepatic vein and the tributaries of the middle hepatic vein by interposing a great saphenous vein (GSV) graft and the anastomosis of the hepatic arteries and bile ducts.

RESULTS

No severe complications and death occurred in all donors. In the first 2 patients, (patients 1 and 2), operative procedure was not modified. One patient suffered from "small-for-size syndrome" and the other died of sepsis with progressive deterioration of graft function. In the rest 22 patients (patients 3 to 24), however, the procedure of venous reconstruction was modified, and better results were obtained. Complications occurred in 7 recipients including acute rejection (2 patients), hepatic artery thrombosis (1), bile leakage (1), intestinal bleeding (1), left subphrenic abscess (1), and pulmonary infection (1). One patient with pulmonary infection died of multiple organ failure (MOF). The 22 patients underwent direct anastomosis of the right hepatic vein to the inferior vena cava (IVC), 9 direct anastomosis plus the reconstruction of the right inferior hepatic vein, and 10 direct anastomosis plus the reconstruction of the tributaries of the middle hepatic vein by interposing a GSV graft to provide sufficient venous outflow. Trifurcation of the portal vein was met in 3 patients. Venoplasty or separate anastomosis was performed. The ratio of graft to recipient body weight ranged from 0.72% to 1.17%. Among these patients, 19 had the ratio <1.0% and 4 <0.8%, and the ratio of graft weight to recipient standard liver volume was between 31.86% and 62.48%. Among these patients, 10 had the ratio <50% and 2 <40%. No "small-for-size syndrome" occurred in the 22 recipients who were subjected to modified procedures.

CONCLUSIONS

With the modified surgical techniques for the reconstruction of the hepatic vein to obtain an adequate outflow and provide a sufficient functioning liver mass, living donor liver graft in adults using the right lobe can be safe to prevent the "small-for-size syndrome".

Fusion of the midplane with the left intersectional plane: a liver anatomical variation revisited with multidetector-row CT

This article updates the description of an anatomical variation of the liver, in which the gallbladder is adjacent to the ligamentum teres, that was described until now as "right-sided ligamentum teres and right umbilical portion of the portal vein". A study of eight patients showing this anatomical variation has led to a new archetypal anatomical description of the hepatic and portal veins, using multidetector-row computed tomography (MDCT) with three-dimensional (3D) volume-rendering (VR) reconstructions. While 2D axial imaging gave the same information, MDCT imaging with VR reconstructions provided a clear 3D visualization of this anatomical variation. Typical features can be described as follows: (1) juxtaposition of the ligamentum teres and the gallbladder; (2) typical portal vein branching with a right posterior branch, a left posterior branch and a main medial branch that terminates in the ligamentum teres; (3) two main hepatic veins and a hypotrophied medial hepatic vein. We think, based on the direct comparison of anatomical findings and knowledge of chronological embryological development, that this abnormality results from the defective development of the central part of the liver and not from the persistence of the right rather than the left umbilical vein. Because of the presence of only one medial plane, containing both the gallbladder and the ligamentum teres, we propose renaming it "fusion of hepatic planes".

The "territorial belonging" of the middle hepatic vein: a troublesome dilemma in adult live donor liver transplantation--anatomical evidence based on virtual 3-dimensional-computed tomography-imaging reconstructions

BACKGROUND

The venous drainage of the liver plays an essential role in securing viability of both graft and remnant in live donor liver transplantation (LDLT). There is still controversy on whether the middle hepatic vein (MHV) should be routinely included as part of the graft or retained with the remnant liver. The purpose of this study was to analyze hepatic venous drainage patterns based on information obtained by 3-dimensional CT-imaging reconstructions.

METHODOLOGY

Fifty five potential live liver donors were evaluated between January 2003 and May 2004 at our Institution. We analyzed two anatomical definitions of liver dominance: total liver dominance (TLD) and hemiliver dominance (HLD). The following concepts were addressed: 1) Hepatic vein territories, 2) Hepatic vein dominance relationship, 3) Territorial belonging- patterns of the MHV to the right and left hemilivers, additionally an analysis of venous outflow in the central liver sectors was performed.

RESULTS

Our results showed that: 1) The definitions of dominance: TLD vs. HLD overlap, displaying the MHV belonging, by taking into account the individual right hepatic vein (RHV) variability; 2) A dominant RHV for the whole liver indicates that the RHV is also dominant in the right hemiliver; 3) The MHV belongs predominantly to the left hemiliver (LHL); 4) The left hepatic vein (LHV) is dominant in the LHL.

CONCLUSION

Both dominance definitions provide independent mappings of the liver and offer helpful insight into venous dominance relationship.

Three-dimensional vasculature of the bovine liver

To clarify anatomical distribution of Fasciola infection, the vascular and ductal architectures of the liver were studied by means of corrosion cast technique using synthetic resin. The arteria hepatica propria (AP) passes as the arteria gastroduodenalis (AG); AP becomes the left trunk after the porta hepatis; AP passes on the right side of vena porta communis (VPC) and projects AG while curving in a U-shape below the portal vein. Hepatic veins located between the vena hepatica media (HM) and vena hepatica dextra (HD) varied widely among specimens and were irregular, including the vena hepatica dorso-lateralis sinistra (Hds), vena hepatica dorso-lateralis dextra (Hdd), vena hepatica lobi caudati (Hlc), venae hepaticae processus caudati (Hpc), venae hepaticae processus papillaris (Hpp), and the hepatic vein to the dorsal intermediate part, which directly or indirectly drained into the vena cava caudalis. The courses of the bovine hepatic veins were markedly diverse, and anastomoses between vena hepatica sinistra (HS) and Hds were observed in about a half of the livers. The portal vein entered the liver as VPC slightly above the centre of the right lobe on the visceral surface. The intermediate or transverse part [pars transversa trunci sinistri (PTS)] of truncus sinister (TS), which extends from the entry of the portal vein into the left lobe of the liver, was slightly arched downward [pars umbilicalis trunci sinistri (PUS)]. The portal vein further arched from the distal end of TS to the umbilical vein and ran towards the inter-lobar incision between the left lobe and quadrate lobe. Based on these branches, hepatic segments were determined as 13 or 14 areas. A total of 15 bile ducts were derived from various lobes. The hepatic duct was about 2.6-6 cm long from the confluence of the right and left hepatic ducts to the division of the cystic duct and the common hepatic duct.

[Retrohepatic veins of the posterior section of the right hepatic lobe--terminology and surgical significance]

Three main hepatic veins: right, middle and left are constant, but there is a variable number of retrohepatic vessels called accessory or minor hepatic veins. The most important of them are veins reffered to as middle right hepatic vein (MRHV) draining segment VII and inferior right hepatic vein (IRHV) draining segment VI. The incidence of large MRHV and IRHV reaching or exceeding a caliber of 5mm, their arrangement in the liver and drainage territories were investigated in our collection of 142 injection-corrosion specimens of the liver. In 1/5 of the cases with large IRHV this vein drains small part of segment VI, sometimes its insignificant marginal part so it couldn't be used for segment VI preservation when it is necessary. A precise knowledge of the vein anatomy of right posterior sector of the liver and its vein drainage territories is very important during complex dissections of the retrohepatic areas, resections and preservation liver parenchima.