Prevalence and Types of Main and Right Portal Vein Branching Variations on MDCT

Effect of Portal Vein Types on Estimated Remnant Volume in Living Donor: Preoperative CT Assessment

PURPOSE

The aim of this study is to examine the effect of portal vein types on the ratio of the right-left lobe liver volumes, as well as the insufficient estimated remnant liver volume (ERLV) during the preoperative assessment of donor candidates for right-lobe liver transplantation.

MATERIALS AND METHODS

The preoperative abdominal CT examinations of the donor candidates in a single institution between December 2018 and May 2022 were retrospectively evaluated. Portal vein types are divided into 3; classical anatomy was considered type 1, PV trifuction was considered type 2, and if the first branch arising from the main portal vein is the right posterior branch, it was accepted as type 3. Other configurations were defined as type 4. The total, right-left lobe liver volumes, the ERLV, and the portal vein variations were noted. The chi-square test was performed to assess the correlation between portal vein types, the ratio of the right-left lobe volumes, and the ERLV ratio below 30%. Tamhane's T2 post hoc tests were performed for pairwise comparison to assess the right-left lobe volume ratio among groups.

RESULTS

287 donor candidates (mean age, 35 years ± 8.2; 174 men) were evaluated. The volume ratio of median volume of the right and left lobe was significantly higher in candidates with type 3 portal veins compared to those with type 1 portal veins (2 (1.3-3.5) and 2.1 (1.6-3.2), respectively, p = 0.017). The ERLV ratio below 30% was significantly higher in donor candidates with type 3 portal veins (42.9%) compared to those with type 1 and 2 portal veins (24.6%, 20%)) respectively, p = 0.030).

CONCLUSION

Due to its propensity to result in insufficient ERLV in the donor, the presence of a type 3 portal vein should be evaluated during the preoperative evaluation. Secondary abstract: This study suggests that donor candidates with type 3 portal vein exhibit a notable rise in the frequency of insufficient remnant liver volume during the preoperative assessment.

Classification of variant portal vein anatomy based on three-dimensional CT: surgical implications

PURPOSES

The purpose of this study was to develop a new and more comprehensive classification system for portal vein (PV) variations using three-dimensional visualization and evaluation (3DVE) and to discuss the prevalence rates and clinical implications of the variants.

METHODS

The anatomies of PVs were tracked and analyzed by using three-dimensional visualization of CT images acquired between 2013 and 2022. Scans from 200 adults were evaluated and a total of 178 patients (N = 178) were included in the study. The new classification system, named BLB classification, was developed based on the level of the absent PV branch in each variant anatomy.

RESULTS

Using the BLB classification system, PVs were divided into thirteen subtypes. Only 82.6-84.8% of the portal veins of the 178 patients were depicted in Atri's, Cheng's or Covey's classification, compared with 100% identified by the BLB classification. The BLB classification was validated against external data sets from previous studies, with 97.0-98.9% of patients classified by the BLB system.

CONCLUSION

Variant PV anatomies are more commonly seen based on 3DVE than in previous reports. The BLB classification covers almost all portal vein variants and may be used for planning liver surgery.

Hilar Anatomy in 3035 Living Liver Donors: A Novel Classification for Donor Surgery and Suitability, Hepatic Surgeries, and Hepatobiliary Interventions

BACKGROUND

This study examines the vascular and biliary variations in 3035 liver donors. We propose a novel classification of hepatic arteries, portal veins, and bile ducts and clinically relevant donor classification.

METHODS

Preoperative imaging and operative details of 3035 donors from 2005 to 2020 were reviewed. Hilar anatomical variations were identified and grouped on the basis of incidence and clinical relevance.

RESULTS

Hilar structures are classified according to the numbers supplying or draining the graft: for the hepatic artery, right (R) and left (L), RA1/LA1 (1 artery), RA2/LA2 (2 arteries), and RA3/LA3 (3 arteries), respectively, further defined on the basis of the inflow trunk into C (for common hepatic artery), S (for superior mesenteric artery), and L (for left gastric artery); for the portal vein, RP1 (1 vein) and RP2 (2 veins) for the right lobe; and for the hepatic duct, RB1/LB1 (1 duct), RB2/LB2 (2 ducts), RB3 (3 right ducts), and RB4 (4 right ducts). Donors were classified on the basis of anatomical variations into 3 groups: class 1 and class 2 donors, who can donate liver with acceptable risks, and class 3 donors, who are high-risk donors because they are anatomically unacceptable ( Figures S1 to S4, SDC , http://links.lww.com/TP/C918 ).

CONCLUSIONS

Defining hilar anatomical variations and donor grouping into anatomy-based clinical classes helps in operative planning of donors, hepatobiliary surgeries, and interventional procedures.

Hepatic portal vein branching patterns according to different liver assessment methods and classifications of branching type

BACKGROUND

It is known that there are varying frequencies of hepatic portal vein branching patterns found in the literature. Studies use different methods and classifications to evaluate the anatomy of the portal vein, which limits accurate comparison between studies and the determination of true frequency of branching patterns in different populations. The aim of the present study was to investigate the intrahepatic branching of the portal vein in corrosive samples using different methods - somatoscopic and computed tomography (CT) and compare with similar studies as well as compare the reclassified data according to the most popular classifications used in the literature.

METHODS

A total of 105 liver corrosion specimens from the 1960-1980 period (51 male and 54 female individuals; min-max age variation - 21-90 y., M=59,46 y.) were investigated. The branching patterns of the hepatic portal vein (HPV), left (HPV-LB) and right branch of hepatic portal vein (HPV-RB), and their segmental branches were examined and scanned by CT. Standard HPV ramification was considered, when HPV divided into HPV-LB and HPV-RB, HPV-RB bifurcated to the anterior and posterior branches, and further segmental ramification into the superior and inferior branches was considered standard. We compared the HPV main branch length and diameter measurements between manual and CT method. A review of the literature was performed on portal vein branching variations.

RESULTS

The standard HPV ramification pattern was detected in 85.7% of the cases in both somatoscopic and CT evaluation. Variations related to the main branches were HPV trifurcation - 7.6%, posterior branch of right branch of hepatic portal vein from HPV - 4.8% and 5.7%, HPV quadrifurcation 1.9% and 1% respectively, in somatoscopic and CT evaluation. There was a significant difference between HPV-LB length and diameter in CT and manual measurements. According to the literature, more variations are seen using the CT method versus somatoscopic corrosion cast evaluation. The varying frequency in studies may be explained by a lack of one unanimous classification of branching patterns (some authors do not consider segmental variations as standard HPV ramification) and different evaluation methods.

CONCLUSION

Somatoscopic evaluation of the branching patterns of the hepatic portal vein in corroded specimens and their CT reconstructions did not differ significantly (which allows relatively accurate comparison of old specimens with newer data). However, the ability to evaluate the reconstructed 3D images of the specimens allowed a more accurate assessment of segmental branching and measurements of lengths and diameters. Standard HPV branching (according to a self-developed classification) in this study was 85.7%. Depending on the classification, the rate of standard branching in the same corrosive samples varied from 63.8% to 84.8% of all cases, indicating that the lack of a unified and stable classification makes it difficult to compare the results of different studies. Deviations from standard branching are very important in surgical procedures and liver transplantation.

Blood flow reconstruction in portal vein anatomical variations in right lobe living donor liver transplantation

Background. Adequate restoration of blood flow through the portal vein in the graft is only possible with a clear understanding of its anatomy in the donor.

The aim was to describe new and extend current data on the portal vein anatomy in a donor of the right liver lobe, to describe variants and formulate principles of portal reconstruction in right lobe living donor liver transplantation.

Material and methods. 306 living donor liver transplantations were performed from 2009 to 2021 in the State Research Center – Burnasyan Federal Medical Biophysical Center of Federal Medical Biological Agency. The vascular anatomy of 518 potential donors was analyzed. Portal vein variants of the anatomy of right lobe graft were assessed.

Results. Nine types and 3 subtypes of portal vein branching were evaluated. A, B, C, D, E types match the types described earlier in Nakamura classification. Subtypes B1, B2 и D1 are specifications of types B and D. Types F, G, H, I have been described additionally. The incidence of types and subtypes where reconstruction was made: type A (82%), B (4.6%), B1 (3.9%), B2 (1.3%), C (3.9%), D (3.9%). The incidence of E, G, H, I types among 518 potential donors was 0.4%, 0.6%, 0.2%, 0.4%, respectively. The recipient portal vein complications were detected in 12 cases (3.9%), where 3(25%) were Class 3b according to Clavien-Dindo and 9(75%) of Clavien-Dindo Class 2. There were no correlations between portal vein complications and the method of portal vein reconstruction. (p<0.05). No complications occurred with portal vein in donors.

Conclusion. The existing classification of right liver graft portal vein has been updated and detailed. A certain way of reconstruction has been proposed for each portal vein type. Anatomical types in which donation and transplantation are contraindicated have been specified.

A systematic review and meta-analysis of portal vein morphometry in pediatric and adult populations: Drawing the line between normal and abnormal findings

PURPOSE

The morphometry of the hepatic portal vein is of clinical importance, particularly in pre-operative assessments, surgical management, and diagnoses of liver conditions. This systematic review and meta-analysis aimed to characterize the morphometry of the normal portal vein in both pediatric and adult patients.

METHODS

The study, conducted using the PRISMA guidelines and registered with PROSPERO, utilized the MEDLINE, EMBASE, SCOPUS and Web of Science databases up to May 2020, and updated to May 2023. All studies reporting extractable data on diameter, length, and cross-sectional area (CSA) of the main, left, and right portal veins (PV, LPV, RPV, respectively) were included. The AQUA Tool was used to assess the quality of the included studies. Data analysis included subgroup analyses based on geographical location, sex, age, and imaging modality.

RESULTS

A total of 122 studies with 11,637 subjects were eligible for inclusion. Overall, the pooled mean diameter of the PV (PVD) was 10.09 mm (95% CI: 9.56-10.62). Significant differences in diameter were found between pediatric (6.60 mm; 95% CI: 5.38-7.82) and adult (10.72 mm; 95% CI: 10.25-11.19) subjects. Additionally, there was a significantly larger PVD measurement from computed tomography (CT) than other imaging modalities: CT, 13.28 mm (95% CI: 11.71-14.84); magnetic resonance imaging (MRI), 10.50 mm (95% CI: 9.35-11.66) and ultrasound (US), 9.81 mm (95% CI: 9.47-10.16). The mean diameters of the LPV and RPV were 8.27 mm (95% CI: 6.78-9.77) and 8.33 mm (95% CI: 6.70-9.95), respectively. Mean PV length in adults is 48.63 mm (95% CI: 35.63-61.64). Mean CSA of the PV was 1.09 cm2.

CONCLUSIONS

The study obtained aim to improve the understanding of portal vein anatomy, especially with relevance to surgical interventions of the liver in both pediatric and adult patients. Measurements from ultrasound imaging closely approximates the generated pooled PVD mean for pediatric and adult patients. CT imaging, however, significantly exceeded the established 13 mm threshold for adults. For pediatric patients, a threshold of 8 mm is proposed as a diagnostic upper limit for a normal PVD. Although not significant, the PVD decreased from the portal confluence towards its bifurcation.

Prevalence of hepatic vascular anomalies in consecutive contrast-enhanced computed tomography images — a retrospective observational study

Background

Liver is a complex, highly vascular organ, where anatomical variations are the norm. This study aimed to analyze all the three hepatic vascular anatomical variations in a single study which would help us understand the prevalence of hepatic vascular (arterial, portal, venous) anomalies in the population catered to by our institution.

Methods

A retrospective analysis of 545 contrast-enhanced CT scans was done from November 2019 from the institute PACS after satisfying the inclusion and exclusion criteria. The raw imaging data were processed in PACS software — Centricity™ Universal Viewer and Syngo.via Vb20 platform, for axial, coronal, and axial-oblique multiplanar reformation, maximum intensity projection (MIP), and volume rendering (VR) images. Data were analyzed in the three vascular phases to determine the anatomical variations. Analysis was done by two surgical residents in the division of HPB surgery, which was verified by a certified radiologist.

Results

There were no major differences in the prevalence rates of the vascular anomalies across gender and domicile distributions. The prevalence of normal hepatic artery and variant hepatic artery in our study was 69% and 31%, respectively. Accessory left hepatic artery (10%) was the most common hepatic artery variant in our study. Single RHV was seen in 77.4%, and other RHV variants like two RHV with common trunk, two RHV with independent drainage, and three RHV with common trunk contribute 22.6% of our study population. Accessory inferior RHV was seen in 19.8% of the study population. Normal portal vein anatomy was found in 81.1% in our study, and the most common variant in our study population was trifurcation of portal vein (16.1%).

Conclusion

This was the largest study until date from South India, studying all three hepatic vascular anatomical variations in a single study. Variations in the anatomy of hepatic arteries, portal veins, and hepatic veins are common. A good knowledge of the same is necessary especially for a hepatobiliary surgeon or for an interventional radiologist, to plan and avoid complications during a procedure. Preoperative contrast-enhanced CT scan and whenever necessary a VR or a MIP reconstruction will precisely help in identifying these variations.

Hepatobiliary-pancreatic surgery for patients with a prepancreatic postduodenal portal vein: a case report and literature review

Background

Prepancreatic portal vein (PPV) is a congenital anatomical variant of the portal vein (PV). PPVs are extremely rare and generally classified into two categories, prepancreatic preduodenal portal vein and prepancreatic postduodenal portal vein (PPPV). Prepancreatic preduodenal portal veins are rare, with approximately 100 reported cases globally; PPPVs are even more atypical, with less than 20 documented cases globally. Despite the extremely low occurrence, PPPV knowledge and recognition are important, especially for hepatobiliary-pancreatic (HBP) surgeries, such as pancreaticoduodenectomy (PD) for patients of a PPPV. Here, we report a case of PPPV and a literature review.

Case presentation

A 73-year-old-male with ampullary carcinoma underwent PD at our hospital. Preoperative enhanced CT revealed an abnormal L-shaped PV, identified as a PPPV. Both the PPPV and the postpancreatic “normal” superior mesenteric vein (SMV) divaricated from the SMV at the caudal side of the pancreas. A splenic vein and inferior mesenchymal vein flowed into the postpancreatic “normal” PV, which encircled the common bile duct and potentially flowed into the liver, forming a cavernous transformation at the hilar plate. During surgery, we attempted to isolate the PV from the pancreas and common bile duct. However, it was difficult to isolate from the pancreas. The PPPV was so fragile that bleeding from the PPPV became uncontrollable. To remove the tumor, we resected the PPPV and reconstructed a “normal” PV as an autogenous graft. To maintain intraoperative hepatic blood flow and avoid small bowel congestion, an antithrombogenic bypass catheter was placed between the SMV and umbilical vein during reconstruction. After surgery, several complications occurred, such as PV thrombosis and hyperammonemia. The patient was discharged on postoperative day 45.

Conclusions

PPPV is a rare vascular variant but is easily diagnosed preoperatively due to its distinct shape on CT imaging. However, isolating the PPPV from the pancreas and bile duct is incredibly difficult and potentially associated with increased operative risks and postoperative complications. PV resection rather than isolation is a potential solution to reduce the risk of hemorrhage, even in the absence of invasion.

Incidence of Extrahepatic Portal Vein Anatomic Variations and Their Clinical Implications in Daily Practice

Anatomical variations of the portal vein are relatively common and can affect the outcomes of hepatic resections, transplantations and interventional radiological procedures. The aim of this study was to review the literature regarding extrahepatic portal vein anomalies. Two main databases were searched for suitable articles, and results concerning more than 3,700 patients were included in the analysis. The most common anatomical variations of the portal vein were trifurcation and having a right posterior portal vein as the first branch of the main portal vein; these anomalies were found in 11.7% and 10.8% of cases, respectively.

Comparative anatomo-radiological study of intrahepatic venous vascularization in the Spain

BACKGROUND

Anatomic variations in the hepatic venous system are the least understood aspect of hepatic anatomy. The variations are diverse, and data are lacking with respect to the population of Spain and methods of detection. The objective was to examine morphological patterns of variations in hepatic venous vascularization using cadaveric dissections vs. radiological imaging, and to analyze the findings with respect to Spain and to published studies.

METHODS

Thirty-one livers were anatomically dissected and analyzed for their hepatic venous anatomy and then compared to the venous anatomy of livers examined in 216 CT scans from 119 men and 97 women, ranging between 27 and 89 years of age. Statistical analysis was done using the Chi squared and Fisher homogeneity tests.

RESULTS

The hepatic portal vein showed morphological variations in cadavers vs. CT of 67.3% vs. 67.6% (p-I), 29% vs. 12.2% (p-II), 0% vs. 14.6% (p-III), 0% vs. 14.6% (p-IV), 3.2% vs. 0.5% (p-V) and 6.5% vs. 1.9% (p-VI), respectively in cadavers vs. CT. Hepatic vein pattern variation were found in 64.5% vs. 50.7% (h-I), 32.2% vs. 31.5% (h-II), 0% vs. 2.3% (h-III), 0% vs. 4.7% (h-IV), respectively in dissections vs. CT). In Accessory Hepatic Veins the frequency in pattern variation was 64.5% vs. 18.8% (a-2.1), 29.0% vs. 8.0% (a-2.2), 58.1% vs. 11.3% (a-2.3), 9.7% vs. 0.9% (a-2.4), 67.7% vs. 16.9% (a-2.5), 9.7% vs. 4.2% (a-2.6) and 0% vs. 0.5% (a-2.7), respectively, in cadavers vs. CT. CT showed in 27.2% no accessory hepatic veins. Sex was not a factor influencing patterns of variation.

CONCLUSION

Anatomical variants of the hepatic portal vein, the hepatic vein and accessory hepatic veins are very diverse and show greater variability in the specimens compared to those detected with radiological images, finding a wider spectrum of variations as it allows the clinician to have a more precise definition of the vasculature. A higher precision in the definition of anatomical variations is warranted for surgical planning in liver resection and transplantation.

Clinical Importance of Main Portal Vein and Right Portal Vein Variations: A Prevalence Study With 128-Slice Multidetector Computed Tomography

OBJECTIVES

The portal vein variation type significantly affects the outcome of transplant surgery, hepatectomies, and interventional radiological procedures. To reveal variation types, especially rare types, we used high-technology multidetector computed tomography.

MATERIALS AND METHODS

We evaluated multiphase abdominal multidetector computed tomography scans of 278 consecutive patients. Multidetector computed tomography scans were processed for axial, coronal, and axial-oblique multiplane reformation and for maximum intensity projection. Variations of the main portal vein and right portal vein were simulta-neously analyzed by 2 radiologists. Prevalence of each variation and differences in sexes were investigated.

RESULTS

Variant anatomy was detected in 29.5% of main portal veins and 20.9% of right portal veins. There was no statistical difference between sexes. Type 3 was reported as the most frequent variant of main portal vein, whereas type 4 was the most frequent variant of right portal vein. Some miscellaneous types were also ascertained.

CONCLUSIONS

Different types of anatomic variations may adversely affect the course of surgery and interventional radiological procedures. Fortunately, radiologists can now discover the critical types by using the new generation multidetector computed tomography with 3-dimensional reconstruction techniques. This information should be included in the radiology reports of patients who are scheduled for major surgery.

Perceptions of porta-celiac vascular models for hepatic surgery and their use in residency training

BACKGROUND

Primary aspect of hepatic navigation surgery is the identification of source vascular details to preserve healthy liver which has a vascular anatomy quite challenging for the young surgeons. The purpose was to determine whether three-dimensional (3D) vascular pattern models of preoperative computed tomography (CT) images will assist resident-level trainees for hepatic surgery.

METHODS

This study was based on the perception of residents who were presented with 5 different hepatic source vascular patterns and required to compare their perception level of CT, and 1:1 models in terms of importance of variability, differential of patterns and preoperative planning.

RESULTS

All residents agree that models provided better understanding of vascular source and improved preplanning. Five stations provided qualitative assessment with results showing the usefulness of porta-celiac models when used as anatomical tools in preplanning (p = 0.04), simulation of interventional procedures (p = 0.02), surgical education (p = 0.01). None of the cases had scored less than 8.5. Responses related to understanding variations were significantly higher in the perception of the 3D model in all cases, furthermore 3D models were more useful for seniors in more complex cases 3 and 5. Some open-ended answers: "The 3D model can completely change the operation plan" One of the major factors for anatomical resection of liver transplantation is the positional relationship between the hepatic arteries and the portal veins.

CONCLUSION

The plastic-like material presenting the hepatic vascularity enables the visualization of the origin, pattern, shape, and angle of the branches with appropriate spatial perception thus making it well-structured.

Variations of the right branch of hepatic portal vein in children based on three-dimensional simulation technology

PURPOSE

To study the variations of the right branch of the hepatic portal vein in children.

METHODS

A total of 810 children's abdominal CT images were reconstructed with three-dimensional (3D) simulation software, Variations of the right branch of the hepatic portal vein were analyzed and classified.

RESULTS

The most common anatomy (type A) was seen in 355 patients (43.83%). Trifurcation in the right anterior portal vein (type B) variation was seen in 250 cases (30.86%). The right posterior portal vein arched without obvious branching (type C) was seen in 71 cases (8.77%). There were 134 special variants (16.54%) named type D, including 14 cases (1.73%) with the right anterior branch in four sub-branches, 13 cases (1.60%) in one trunk and multiple sub-branches, 92 cases (11.36%) originating from the left trunk of the portal vein, and 15 cases (1.85%) with the VI segment of the portal vein originating from the right anterior branch of the portal vein.

CONCLUSION

Variations in the right branch of the hepatic portal vein seems to be very frequent. Recognition of such variations is important in the preoperative evaluation of children with surgery planned, because these variations may have implications for anatomy-guided liver resection and for planning the operative approach.

Role of CT Imaging With Three-Dimensional Maximum Intensity Projection Reconstruction in the Evaluation of Portal Vein Variants at a Tertiary Care Hospital

INTRODUCTION

Portal vein (PV) is the principal blood vessel transporting blood from the alimentary tract and spleen to the liver. The aim of this study is to determine the prevalence of PV anatomical variations in our population using multidetector CT with maximum intensity projection (MIP) technique at a tertiary care hospital.

METHODS

This cross-sectional study was prospectively conducted from November 2018 to June 2019 in the Department of Radiology at a tertiary care hospital in Karachi. After informed consent, all the patients with no known hepatic pathology undergoing routine abdomen CT were included in this study. Patients with previous hepatic resection surgeries, undiagnosed large hepatic tumors/metastasis, and those with PV thrombosis were excluded.

RESULTS

A total of 500 patients (256 males and 244 females) were included in the study; the mean age of female patients was relatively higher as compared to the male patients (53.80 ± 18.44 vs. 44.15 ± 19.94 years; p = 0.000). Standard PV anatomy (type 1) was found in 438 patients (87.6%). Trifurcation (type 2) occurred in 18 patients (3.6%). Right posterior portal vein as the first branch of main PV (type 3) was found in 22 patients (4.4%). A separate branch of the right portal vein (RPV) to segment VII (type 4) and separate branch of the RPV to segment VI (type 5) were found in 6 (1.2%) and 16 (3.2%) patients, respectively.

CONCLUSION

Our study displayed a relatively higher frequency of standard PV anatomy (type 1) compared to previous studies. We highlight the role of MIP in the analysis of hepatic venous anatomy with its utility demonstrating improved detection of variations.

Hepatic vascular variations and visual three-dimensional reconstruction technique in pediatric patients with choledochal cyst

PURPOSE

The aim of the present study was to identify the hepatic vascular variations with visual three-dimensional (3D) reconstruction of vessels in pediatric patients with choledochal cyst (CDC).

METHODS

We retrospectively analyzed the data of 84 children with pathologically confirmed CDCs treated in the Children's Hospital of Soochow University. 180 patients without CDCs as a control to analysis the hepatic artery and portal vein anatomy. All patients were examined by multi-slice spiral CT (MSCT) and the images of children with CDC were reconstructed by Hisense computer-assisted surgery system (Hisense CAS) to obtain visual 3D images.

RESULTS

There were 71 females and 13 males diagnosed with CDC. According to Todani classification of CDC, there were 42 cases of type Ia, 10 cases of type Ic and 32 cases of type IVa. There were 10 (11.9%) patients with hepatic artery variations, 14 (16.7%) patients with right hepatic artery located on the ventral side of the CDC, and 16 (19.0%) patients with portal vein variations. Sex, age and types of the cyst were not associated with the presence of vascular variations. There was no significant difference in hepatic vascular variation between CDCs and control groups. Visual 3D images clearly displayed the hepatic vascular variations and the spatial structure of the CDC in pediatric patients with CDC.

CONCLUSIONS

Hepatic artery and portal vein variations can be detected in pediatric patients with CDC. Visual 3D technique can visually and stereoscopically display the anatomical variations of the hepatic artery and portal vein.

Sonographic Appearances of Portal Vein Abnormalities

Portal venous system evaluation is required in many clinical circumstances, as substantial morbidity and mortality can be associated with a spectrum of portal vein abnormalities. Portal venous system pathologies can be congenital or acquired, and the knowledge of their imaging appearances will allow for a confident diagnosis and appropriate treatment options. In addition, a firm understanding of anatomical variants is important for planning surgical procedures and percutaneous interventions of the liver. This article will review various imaging appearances of portal venous systems abnormalities.

Portal Vein Embolization: Radiological Findings Predicting Future Liver Remnant Hypertrophy

OBJECTIVE. The purpose of this article is to evaluate the radiologic findings predicting the future liver remnant hypertrophy ratio after portal vein embolization of the right branch. MATERIALS AND METHODS. The associations between the radiologic findings and the future liver remnant hypertrophy ratio for 79 patients who underwent portal vein embolization of the right branch between July 2007 and April 2017 were retrospectively analyzed. Multiple linear regression was performed to adjust for potential confounders, and the volume ratio of the right lobe anterior segment, number of proximal small branches from the right anterior and posterior portal veins, transient hepatic parenchymal enhancement, portal vein invasion, and variants of main portal vein anatomy were evaluated. The potential confounders were age, ratio of future liver remnant hypertrophy to total liver volume, indocyanine green clearance rate, maximum serum total bilirubin before portal vein embolization, and history of chemotherapy. RESULTS. Statistically significant associations were found between the future liver remnant hypertrophy ratio and the number of proximal small branches from the right anterior and posterior portal veins (p < 0.001), transient hepatic parenchymal enhancement (p < 0.001), portal vein invasion (p = 0.017), and variants of main portal vein anatomy (p = 0.048). The mean future liver remnant hypertrophy rate was 51.0% (n = 16) in patients without the radiologic findings showing statistically significant differences, and 25.8% (n = 63) in patients with at least one significant finding. CONCLUSION. When added to previously reported factors, the radiologic findings identified can help determine the indications for portal vein embolization and novel strategies for major hepatectomy.

Segmental branching pattern of the left portal vein: Anatomical characteristics and clinical implications

The existing knowledge on anatomy of segmental branches of left portal vein (LPV) is limited. This study aims to describe the surgical anatomy and variations of LPV and its segmental branching pattern. Forty fresh cadaveric liver dissections were performed. The dissection of LPV was carried out from its emergence at the level of the portal vein bifurcation to its segmental branches penetrating the left hemiliver. LPV characteristics, the number, and situation of its segmental branches were recorded. LPV comprises two portions: a 28 ± 6.7 mm-long transverse portion (TPLPV) and a 34.9 ± 4.4 mm-long umbilical portion (UPLPV). Mean number of LPV branches to segments I, II, III, and IV was 2 ± 1 (1-6), 2 ± 1 (1-4), 2 ± 1 (1-5), and 8 ± 2 (4-14), respectively. A single large vein supplied segment II in 90% of the cases. Segment III constantly had one vein arising from the left horn of UPLPV with mean diameter of 5.9 ± 1.6 mm. Most of the veins to segment IV took origin from the right horn of UPLPV with a mean number of 5 ± 2 (2-8). Segmental veins arising from UPLPV and TPLPV and supplying segment IV were present in 90 and 45% of the cases respectively. Segmental veins arising from LPV are often multiple and variable in position. Detailed knowledge of these veins is mandatory in order successfully perform anatomical liver resections or monosegment graft harvest for pediatric liver transplantation. Clin. Anat. 31: 1122-1128, 2017. © 2017 Wiley Periodicals, Inc.

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.

Computed tomography angiography study of variations of the celiac trunk and hepatic artery in 100 patients

Objective

To describe the main anatomical variations of the celiac trunk and the hepatic artery at their origins.

Materials and Methods

This was a prospective analysis of 100 consecutive computed tomography angiography studies of the abdomen performed during a one-year period. The findings were stratified according to classification systems devised by Sureka et al. and Michels.

Results

The celiac trunk was "normal" (i.e., the hepatogastrosplenic trunk and superior mesenteric artery originating separately from the abdominal aorta) in 43 patients. In our sample, we identified four types of variations of the celiac trunk. Regarding the hepatic artery, a normal anatomical pattern (i.e., the proper hepatic artery being a continuation of the common hepatic artery and bifurcating into the right and left hepatic arteries) was seen in 82 patients. We observed six types of variations of the hepatic artery.

Conclusion

We found rates of variations of the hepatic artery that are different from those reported in the literature. Our findings underscore the need for proper knowledge and awareness of these anatomical variations, which can facilitate their recognition and inform decisions regarding the planning of surgical procedures, in order to avoid iatrogenic intraoperative injuries, which could lead to complications.

Depicting surgical anatomy of the porta hepatis in living donor liver transplantation

Visualizing the complex anatomy of vascular and biliary structures of the liver on a case-by-case basis has been challenging. A living donor liver transplant (LDLT) right hepatectomy case, with focus on the porta hepatis, was used to demonstrate an innovative method to visualize anatomy with the purpose of refining preoperative planning and teaching of complex surgical procedures. The production of an animation-enhanced video consisted of many stages including the integration of pre-surgical planning; case-specific footage and 3D models of the liver and associated vasculature, reconstructed from contrast-enhanced CTs. Reconstructions of the biliary system were modeled from intraoperative cholangiograms. The distribution of the donor portal veins, hepatic arteries and bile ducts was defined from the porta hepatis intrahepatically to the point of surgical division. Each step of the surgery was enhanced with 3D animation to provide sequential and seamless visualization from pre-surgical planning to outcome. Use of visualization techniques such as transparency and overlays allows viewers not only to see the operative field, but also the origin and course of segmental branches and their spatial relationships. This novel educational approach enables integrating case-based operative footage with advanced editing techniques for visualizing not only the surgical procedure, but also complex anatomy such as vascular and biliary structures. The surgical team has found this approach to be beneficial for preoperative planning and clinical teaching, especially for complex cases. Each animation-enhanced video case is posted to the open-access Toronto Video Atlas of Surgery (TVASurg), an education resource with a global clinical and patient user base. The novel educational system described in this paper enables integrating operative footage with 3D animation and cinematic editing techniques for seamless sequential organization from pre-surgical planning to outcome.

Identification landmark for right anterior portal pedicle: "the zone of 2 cm"

PURPOSE/BACKGROUND

Cystic plate is easily visible while right anterior portal pedicle (RAPP) is a difficult to identify due to its intrahepatic location. This study aims to determine the relation between these two structures so as to facilitate rapid identification of RAPP during the operation.

METHODS

Thirty-seven cadaveric liver dissections were carried in the Forensic Department at the Charles Nicolle Hospital, Tunisia.

RESULTS

The cystic plate was thin (≤1 mm), medium (1-3 mm), and thick (≥3 mm) in 14 (37.8%), 17 (46%), and 6 cases (16.2%), respectively. RAPP was found to be originating from right, main, and left portal trunk in 29 (78.3%), 6 (16.3%), and 2 (5.4%) livers, respectively. The origin of RAPP was extrahepatic in nine cases (24.3%). RAPP was located underneath the cystic plate in 21 livers (56.8%). Thirteen RAPPs (35.1%) were located to its right at the mean distance of 1.4 cm (range 0.4-2.5). Three RAPPs were present to the left of cystic plate (8.1%) at the mean distance of 0.9 cm (range 0.7-1.3).

CONCLUSION

Rapid identification of RAPP is possible by knowing its anatomic variations and its relation with cystic plate.

Portal vein branching order helps in the recognition of anomalous right-sided round ligament: common features and variations in portal vein anatomy

PURPOSE

This study aimed to evaluate the common features and variations of portal vein anatomy in right-sided round ligament (RSRL), which can help propose a method to detect and diagnose this anomaly.

METHODS

In this retrospective study of 14 patients with RSRL, the branching order of the portal tree was analyzed, with special focus on the relationship between the dorsal branch of the right anterior segmental portal vein (P_A-D) and the lateral segmental portal vein (P_LL), to determine the common features. The configuration of the portal vein from the main portal trunk to the right umbilical portion (RUP), the inclination of the RUP, and the number and thickness of the ramifications branching from the right anterior segmental portal vein (P_A) were evaluated for variations.

RESULTS

In all subjects, the diverging point of the P_A-D was constantly distal to that of the P_LL. The portal vein configuration was I- and Z-shaped in nine and five subjects, respectively. The RUP was tilted to the right in all subjects. In Z-shaped subjects, the portal trunk between the branching point of the right posterior segmental portal vein and that of the P_LL was tilted to the left in one subject and was almost parallel to the vertical plane in four subjects. Multiple ramifications were radially distributed from the P_A in eight subjects, whereas one predominant P_A-D branched from the P_A in six subjects.

CONCLUSIONS

Based on the diverging points of the P_A-D and P_LL, we proposed a three-step method for the detection and diagnosis of RSRL.

Surgical Implications of Portal Vein Variations and Liver Segmentations: A Recent Update

The Couinaud's liver segmentation is based on the identification of portal vein bifurcation and origin of hepatic veins. It is widely used clinically, because it is better suited for surgery and is more accurate in localizing and monitoring various intra parenchymal lesions. According to standard anatomy, the portal vein bifurcates into right and left branches; the left vein drains segment II, III and IV and the right vein divides into two secondary branches - the anterior portal vein drains segments V and VIII, and the posterior drains segments VI and VII. The portal vein variants such as 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 main portal vein were found to be more frequent and was seen in about 20 - 35% of the population. Accurate knowledge of the portal variants and consequent variations in vascular segments are essential for intervention radiologists and transplant surgeons in the proper diagnosis during radiological investigations and in therapeutic applications such as preparation for biopsy, Portal Vein Embolization (PVE), Transjugular Intrahepatic Porto-Systemic Shunt (TIPS), tumour resection and partial hepatectomy for split or living donor transplantations. The advances in the knowledge will reduce intra and postoperative complications and avoid major catastrophic events. The purpose of the present review is to update the normal and variant portal venous anatomy and their implications in the liver segmentations, complex liver surgeries and various radiological intervention procedures.

Cross-sectional imaging of congenital and acquired abnormalities of the portal venous system

Knowing the normal anatomy, variations, congenital and acquired pathologies of the portal venous system are important, especially when planning liver surgery and percutaneous interventional procedures. The portal venous system pathologies can be congenital such as agenesis of portal vein (PV) or can be involved by other hepatic disorders such as cirrhosis and malignancies. In this article, we present normal anatomy, variations, and acquired pathologies involving the portal venous system as seen on computed tomography (CT) and magnetic resonance imaging (MRI).

Portal Vein Embolization as an Oncosurgical Strategy Prior to Major Hepatic Resection: Anatomic, Surgical, and Technical Considerations

Preoperative portal vein embolization (PVE) is used to extend the indications for major hepatic resection, and it has become the standard of care for selected patients with hepatic malignancies treated at major hepatobiliary centers. To date, various techniques with different embolic materials have been used with similar results in the degree of liver hypertrophy. Regardless of the specific strategy used, both surgeons and interventional radiologists must be familiar with each other's techniques to be able to create the optimal plan for each individual patient. Knowledge of the segmental anatomy of the liver is paramount to fully understand the liver segments that need to be embolized and resected. Understanding the portal vein anatomy and the branching variations, along with the techniques used to transect the portal vein during hepatic resection, is important because these variables can affect the PVE procedure and the eventual surgical resection. Comprehension of the advantages and disadvantages of approaches to the portal venous system and the various embolic materials used for PVE is essential to best tailor the procedures for each patient and to avoid complications. Before PVE, meticulous assessment of the portal vein branching anatomy is performed with cross-sectional imaging, and embolization strategies are developed based on the patient's anatomy. The PVE procedure consists of several technical steps, and knowledge of these technical tips, potential complications, and how to avoid the complications in each step is of great importance for safe and successful PVE and ultimately successful hepatectomy. Because PVE is used as an adjunct to planned hepatic resection, priority must always be placed on safety, without compromising the integrity of the future liver remnant, and close collaboration between interventional radiologists and hepatobiliary surgeons is essential to achieve successful outcomes.

CT virtual endoscopy for analyzing variations in the hepatic portal vein

PURPOSE

To evaluate the value of CT virtual endoscopy (CTVE) for accurately distinguishing varying types of portal veins (PVs).

MATERIALS AND METHODS

From 526 consecutive patients whose hepatic portal vein was well visualized, patients who were considered to have trifurcation of the main portal vein (MPV) or right portal vein (RPV) on volume rendering (VR) and maximum intensity projection (MIP) imaging were chosen for the analysis. Two radiologists evaluated the PV anatomy of these patients and re-classified the types of PV variation using the CTVE technique. The Wilcoxon rank sum test was used to calculate differences in age between males and females.

RESULTS

Thirty-two patients (20 males, 12 females; age range 21-68 years; mean age 43 years) were considered to have trifurcation of the MPV (15) or RPV (17) on VR and MIP imaging. Fifteen patients in total had a trifurcation confirmed by CTVE (6 patients were proven to have an MPV trifurcation by CTVE, and 9 were confirmed to have a RPV trifurcation).

CONCLUSIONS

CTVE can differentiate PV variations that cannot be identified accurately on MIP and VR.

Transjugular intrahepatic portosystemic shunt stent-graft placement: mean optimal portal venous projection view determined by three-dimensional portography

BACKGROUND

Suboptimal stent-graft placement at the lower anastomosis during transjugular intrahepatic portosystemic shunt (TIPS) may result in early shunt stenosis and occlusion owing to incomplete covering of the parenchymal tract by the covered part of the stent-graft.

PURPOSE

To determine the optimal portal venous projection view for stent-graft placement during TIPS and the potential influence of the portal vein anatomy.

MATERIAL AND METHODS

On 76 cirrhotic patients (48 men and 28 women) selected for TIPS, rotational, three-dimensional (3D), catheter-directed angiography of the portal vein was performed. The 3D portograms were reviewed by two independent interventional radiologists to determine the optimal angiographic projection views for stent-graft placement. Intra-observer and inter-observer reliabilities were tested and subgroups of patient portal vein anatomy were categorized.

RESULTS

Among all patients, the optimal portal venous projection views for stent-graft placement during TIPS centered around 27° (±14°) right oblique and 3° (±7°) craniocaudal. Of these, 56% were within the standard deviations. Intra-observer reliabilities were 0.60 and 0.62 for the two radiologists, respectively. Inter-observer reliability was 0.48. Anatomical variations in the patient population were: normal portal vein (67%), trifurcation at main portal vein (16%), right posterior portal vein as the first branch of main portal vein (3%), no right posterior portal vein (1%), and other variations (13%). Anatomical subgroups did not influence the best angiographic projection view significantly (F4,295 = 0.91, P = 0.457).

CONCLUSION

The mean optimal angiographic projection view for TIPS stent-graft placement was 27° right oblique and 3° craniocaudal. Patient anatomic variations do not play a significant role in determining the optimal angiographic view for TIPS stent-graft placement.

Imaging assessment of congenital and acquired abnormalities of the portal venous system

Abnormalities of the portal venous system are a heterogeneous group of conditions that can cause substantial morbidity and mortality and may lead to complications during surgery or percutaneous interventions involving the portal venous system. High-resolution computed tomography, ultrasonography, and magnetic resonance imaging permit a comprehensive, noninvasive evaluation of the portal venous system, enabling the detection of both structural and functional abnormalities. However, an understanding of the embryologic development of the normal portal venous anatomy and anatomic variants is essential to accurately interpret the imaging findings. Knowledge of the characteristic appearances of abnormalities of the portal venous system allows a more confident diagnosis, permitting timely treatment and more informed guidance of surgical procedures and percutaneous interventions, which may lead to an improved outcome.

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.

In-utero evaluation of the fetal umbilical-portal venous system: two- and three-dimensional ultrasonic study

OBJECTIVES

To describe the normal anatomy of the fetal umbilical-portal venous system (UPVS) and to assess possible anatomical variants of the main portal vein (MPV) insertion into the portal sinus (PS).

METHODS

This was a prospective cross-sectional study of low-risk patients between 14 and 36 weeks of gestation. Two- (2D) and three-dimensional (3D) ultrasound techniques combined with color and high-definition flow Doppler were used to evaluate the fetal UPVS. The standard transverse plane of the fetal upper abdomen, used for measuring the abdominal circumference, was taken in all cases as the point of reference. A longitudinal section was taken to identify the normal course of the umbilical vein and ductus venosus (DV). We performed offline analysis of all gray-scale and color Doppler 2D and 3D volume datasets.

RESULTS

Two hundred and eight fetuses were included in the study. The umbilical vein was observed to course in a cephalad direction from its entry point into the fetal abdomen, joining the L-shaped PS, a confluence of vessels that is the main segment of the left portal vein (LPV). Three branches emerge from the LPV: two to the left, the inferior and superior branches, and one to the right, the medial branch. The main LPV then courses abruptly to the right. Following the emergence of the DV, the communication of the MPV with the LPV marks the point at which the vessel becomes the right portal vein (RPV), giving rise to its anterior and posterior branches. We were able to define three main variants of connection between the MPV and the PS. In 140 (67.3%) fetuses the MPV was connected to the LPV in an end-to-side T-shaped anastomosis, in 26 (12.5%) fetuses the MPV connected with a side-to-side X-shaped anastomosis and in 30 (14.4%) fetuses the two vessels ran in parallel with a short communicating segment, in an H-shaped anastomosis. In the remaining 12 (5.7%) cases classification into one of these three groups was not possible due to intermediate morphology.

CONCLUSIONS

Knowing the normal anatomy of the UPVS and being aware of the possible variants of the connection between the MPV and the PS is a fundamental requirement for accurate prenatal diagnosis of the anomalies of the fetal UPVS.

Multidetector computed tomography angiography in the evaluation of potential living donors for liver transplantation: single-center experience in China

OBJECTIVE

To evaluate relevant arterial, hepatic, and portal venous anatomy using multidetector computed tomography (CT) angiography in potential living liver donors at a single liver transplantation center in China.

METHODS

One hundred two consecutive potential liver donors underwent CT angiography in the arterial, portal, and hepatic venous phases with a 16-row CT scanner. All source and reconstructed images were evaluated for hepatic vasculature anatomy by an experienced radiologist and a surgeon in consensus. The anatomic variants of arterial system, portal venous system, and hepatic veins were characterized according to the classification system of Michels, Akgul, and Nakamura respectively. In 42 donors of right hepatic lobectomy, CT findings were compared with the results of surgery.

RESULTS

Of 102 candidates, 63 had type I, 8 type II, 12 type III, 3 type IV, 11 type V, 2 type VI, 2 type VIII, and 1 type IX hepatic arterial anatomy. According to the classification of the portal venous system created by Akgul, type A was seen in 81 subjects. Type B, type C, and type E were revealed in 15, 4, and 2 subjects, respectively. According to the classification of the right hepatic drainage pattern by Nakamura, type 1 drainage was seen in 71 subjects (69.6%), type 2 in 22 candidates (21.6%), and type 3 in 9 subjects (8.8%). Forty five right inferior hepatic veins were identified in 41 potential donors, and 68.9% of these veins were larger than 5 mm in diameter. CT angiography findings were confirmed in all donors who underwent operations.

CONCLUSIONS

Multidetector CT angiography can successfully show the relevant hepatic vascular anatomy in potential liver donors.