Usefulness of three-dimensional computed tomography in a living-donor extended right lobe liver transplantation

Consensus recommendations of three-dimensional visualization for diagnosis and management of liver diseases

Three-dimensional (3D) visualization involves feature extraction and 3D reconstruction of CT images using a computer processing technology. It is a tool for displaying, describing, and interpreting 3D anatomy and morphological features of organs, thus providing intuitive, stereoscopic, and accurate methods for clinical decision-making. It has played an increasingly significant role in the diagnosis and management of liver diseases. Over the last decade, it has been proven safe and effective to use 3D simulation software for pre-hepatectomy assessment, virtual hepatectomy, and measurement of liver volumes in blood flow areas of the portal vein; meanwhile, the use of 3D models in combination with hydrodynamic analysis has become a novel non-invasive method for diagnosis and detection of portal hypertension. We herein describe the progress of research on 3D visualization, its workflow, current situation, challenges, opportunities, and its capacity to improve clinical decision-making, emphasizing its utility for patients with liver diseases. Current advances in modern imaging technologies have promised a further increase in diagnostic efficacy of liver diseases. For example, complex internal anatomy of the liver and detailed morphological features of liver lesions can be reflected from CT-based 3D models. A meta-analysis reported that the application of 3D visualization technology in the diagnosis and management of primary hepatocellular carcinoma has significant or extremely significant differences over the control group in terms of intraoperative blood loss, postoperative complications, recovery of postoperative liver function, operation time, hospitalization time, and tumor recurrence on short-term follow-up. However, the acquisition of high-quality CT images and the use of these images for 3D visualization processing lack a unified standard, quality control system, and homogeneity, which might hinder the evaluation of application efficacy in different clinical centers, causing enormous inconvenience to clinical practice and scientific research. Therefore, rigorous operating guidelines and quality control systems need to be established for 3D visualization of liver to develop it to become a mature technology. Herein, we provide recommendations for the research on diagnosis and management of 3D visualization in liver diseases to meet this urgent need in this research field.

Hepatic venous drainage: how much can we learn from imaging studies? Anatomic-functional classification derived from three-dimensional computed tomography reconstructions

BACKGROUND

The knowledge of "venous dominance" is essential to prevent serious venous congestion in live donor liver transplantation and extended liver resections.

AIMS

The purpose of our study was to delineate our proposed anatomic-functional classification of hepatic venous drainage.

METHODS

One hundred forty consecutive live liver donor candidates underwent three-dimensional computed tomography reconstructions and three-dimensional virtual hepatectomies. Five different venous dominance types were defined on drainage volumes or territories. "Risky" configurations were identified and classified.

RESULTS

The right hepatic vein (RHV) was dominant for the entire liver and right hemiliver (RHH) in most (83.5%) cases irrespective of the presence of inferior (accessory) hepatic veins (IHVs). The middle hepatic vein (MHV) was dominant for the total liver (TL) in 15.5% of cases and for the RHH in 27% of cases. The left hepatic vein was almost always (92%) dominant for the left hemiliver. When associated with a large IHV drainage volume, a RHV/IHV complex dominant for the TL led to a RHH dominant MHV (mean 59.5%RHH) if the IHV was not reconstructed.

CONCLUSIONS

Our proposed anatomic-functional classification provides a valuable insight into hepatic vein dominance patterns. RHH venous drainage patterns at "high risk" for venous congestion include (1) a dominant MHV for the TL and (2) a dominant RHV/IHV complex with a large IHV drainage volume.

Normal vascular and biliary hepatic anatomy: 3D demonstration by multidetector CT

Due to constant innovations in radiological and surgical techniques, more accurate results are expected in the diagnostic and therapeutic procedures related to hepatic pathology. The aim of this work was to demonstrate the normal hepatic vascular and biliary anatomy using cadaveric livers and CT scans of the affected livers. Furthermore, using the CT scans, the authors intended to illustrate the most common morphological variations of the vascular and biliary anatomy. Four human cadaveric livers were injected with colored silicone mixed with radiological contrast solution in the common bile duct, in the proper hepatic artery, in the portal vein and in the inferior vena cava near the ostia of the hepatic veins (only one of these structures was injected in each liver). After obtaining the CT scans, 3D rendered models were created, which demonstrated the normal hepatic anatomy of the vascular and biliary structures. The International Anatomical Nomenclature was used for their classification (based on Couinaud's work). The 3D rendered CT models were also modified to illustrate the most common normal variations of the hepatic anatomy (found in the literature).

The impact of 3-D virtual hepatectomy simulation in living-donor liver transplantation

BACKGROUND/PURPOSE

In living-donor liver transplantation, accurate assessments of liver graft volume and anatomical variation are mandatory for the preoperative planning of safe donor hepatectomy and successful recipient implantation. The aim of this study was to assess the feasibility and accuracy of novel three-dimensional (3-D) virtual hepatectomy simulation software in living-donor liver transplantation.

METHODS

We developed the hepatectomy simulation software, which was programmed to analyze detailed 3-D vascular structure and to predict liver graft volume, based on hepatic circulation.

RESULTS

In 101 individuals, including 4 living donors, the predicted liver resection volumes revealed a significant correlation with the actual value (P < 0.0001), with a mean difference of 7.9 ml. The drainage area by the individual hepatic vein branch was quantified to achieve reconstruction of the corresponding venous branch. The application of multidetector computed technology scanning and virtual cholangioscopy facilitated more detailed visualization of the 3-D hilar anatomy in a left trisectoral graft transplantation.

CONCLUSIONS

This hepatectomy simulation software reliably predicted accurate liver graft volume and the drainage volume of hepatic vein branches. This software may contribute to the preoperative planning of safe donor hepatectomy and implantation with satisfactory graft viability.

Computer-assisted operative planning in adult living donor liver transplantation: a new way to resolve the dilemma of the middle hepatic vein

An adequate venous outflow is essential for securing viability of both graft and remnant in adult living donor liver transplantation (ALDLT). Seventy-five potential live liver donors were evaluated for LDLT by means of an "all-in-one" CT, which defined the biliary tree, portal vein, hepatic artery, and hepatic vein anatomy. The acquired data sets were further analysed by means of the software HepaVision (MeVis, Germany). Only a minority (29%) of potential donors were found to have a vascular and biliary anatomy consistent with the classically described "normal" patterns. The vast majority (71%) had "anatomical variations". Thirty-nine (52%) donors underwent ALDLT hepatectomy. The right hepatic vein was dominant in 64 cases, representing 48 +/- 6% of the total liver volume (TLV). The middle hepatic vein was dominant in 11 cases, making up 40 +/- 8% of the TLV. The left hepatic vein was never dominant. The volume contribution of the middle hepatic vein (MHV) was 114-782 ml for the right and 87-419 ml for the left hemiliver. Computer-assisted planning allows for the 3D reconstruction of the vascular and biliary anatomy, automatic calculation of the total and territorial liver volumes, and risk analysis of hepatic vein dominance relationships. This comprehensive data acquisition supports preoperative evaluation and provides a high degree of safety for donors and improved outcomes for recipients.

Hepatic vein anatomy of the medial segment for living donor liver transplantation using extended right lobe graft

Hepatic vein anatomy (V4) of the medial segment (S4) has been a matter of concern since introduction of extended right lobe (ERL) graft. To assess risk of hepatic venous congestion (HVC) in ERL donors, we tried to newly classify V4 anatomy. We analyzed V4 anatomy of 328 living donor livers by using 3-dimensional reconstruction (3-DR) and volumetry of computed tomography (CT). Variations of V4 were divided into type A (middle hepatic vein [MHV] dominant: n = 142, 43.3%), type B (MHV-dominant, but enabling preservation of dorsal V4 branch [V4b]: n = 40, 12.2%), type C (mixed: n = 92, 28%), and type D (left hepatic vein dominant: n = 54, 16.5%). We analyzed the amount of HVC at S4 in 143 donor livers of right lobe (RL) and ERL grafts. Occlusion of MHV trunk induced HVC equivalent to 85.2%, 85.4%, 55.2%, and 35.4% of S4 volume and 34%, 33.9%, 20.3%, and 14.2% of left liver volume in livers of types A, B, C, and D, respectively. Tailored V4b preservation reduced HVC significantly in type B livers. Considering that functional capability may be decreased in HVC portion, functional hepatic resection rate (FHRR) of ERL graft procurement ranged as follows: 62.3%-75% in type A; 62.2%-75% and 62.2%-68.7% in type B with and without V4b preservation, respectively; 63.2%-70.7% in type C; and 61.8%-67.2% in type D. These results support the theory that these categories of V4 types are closely correlated with potential amount of HVC at S4, reflect the possibility of V4b preservation, and are compatible with CT findings. We believe that this V4 classification is applicable to assess donor V4 anatomy in practice.

Peripheral anatomic evaluation using 3D CT hepatic venography in donors: significance of peripheral venous visualization in living-donor liver transplantation

OBJECTIVE

The purpose of this study was to determine clinical roles for 3D CT hepatic venography in the evaluation of peripheral hepatic venous anatomy during living-donor liver transplantation.

MATERIALS AND METHODS

Subjects comprised 54 donors (age range, 20-60 years) who had undergone surgery to donate a liver for transplantation. Visualization of each hepatic venous branch and total visualization using 3D CT hepatic venography were evaluated. Maximum venous branch order visualized was graded as nil, first branch, second branch, or third branch or more. The distance between the hepatic surface and the tip of each hepatic venous branch was classified as 0-5 mm, 6-10 mm, 11-15 mm, 16-20 mm, or 21-25 mm. Quality of total 3D CT hepatic venography was evaluated subjectively as poor, good, fair, or excellent. Dominance of large hepatic veins in the right lobe, peripheral branching pattern of the middle hepatic vein, and branching pattern of the vein draining segment IVb were also assessed.

RESULTS

Most hepatic venous branches (96.2% [275/286]) were visualized up to at least the second-order branches, and 93.7% (268/286) of branches were within 10 mm of the hepatic surface. As for total visualization, 98% (53/54) of cases were regarded as excellent. The dominant vein in the right lobe was the right hepatic vein in 27 cases, inferior hepatic vein in 25, and middle hepatic vein in one. The branching pattern of the middle hepatic vein was type 1 in 36 cases, type 2 in nine, and type 3 in eight. Segment IVb vein branched from the middle hepatic vein in 20 patients, and from the left hepatic vein in 34.

CONCLUSION

Because 3D CT hepatic venography visualizes peripheral hepatic venous branches in detail, the technique is useful for determining operative indications in living-donor liver transplantation.

New concepts in organ transplantation

Over the past several decades, many factors have led to higher rates of patient and graft survival in organ transplantation. These factors include enhanced immunosuppressants available in recent years such as Neoral, Prograf, sirolimus, mycophenolate mofetil and anti-interleukin-2 receptor monoclonal antibodies. In addition, other new drugs, such as FTY 720, FK 778, anti-CD20, anti-CD40, and anti-CH52 monoclonal antibodies, are now being tested in clinical studies. Furthermore, there have been advances in surgical techniques, such as the piggyback method without venovenous bypass, side-to-side anastomosis of the hepatic veins, use of vascular staplers, biliary duct-to-duct anastomosis with or without tube drainage, microsurgical hepatic artery anastomosis and laparoscopic donor nephrectomy. Finally, better patient and donor selection criteria with regard to HBV- and HCV-seropositive donors, diabetic donors, donors with malignancies, older donors, ABO-incompatible donors, and non-heart-beating donors have been combined with optimal timing of transplantation, better options for treating early surgical and late medical complications, and improved management in intensive-care units. Other noteworthy scientific and social development are on the horizon namely genetic advances in xenografting and cell transplantation, and induction of immunologic tolerance. This article reviews the current developments that have significantly improved graft and patient survival among solid-organ transplants.

Living related small bowel transplantation in children: 3-dimensional computed tomography donor evaluation

The evaluation of the small bowel vascular anatomy of living small bowel donors (LSBD) is usually performed with conventional angiography (CA). Recently, angio computed tomography (CT) has become a valid study of the vascular anatomy for kidney and liver living donors. We studied the applicability of angio CT with 3-D reconstruction (3-D-ACT) in the evaluation of LSBD. Potential LSBDs for pediatric transplant underwent both CA and 3-D-ACT to evaluate the anatomy of the distal branches of the superior mesenteric artery and vein. Angio-CT was performed with General Electric Lightspeed Scanner. The 3-D reconstruction was performed on the TeraRecon workstation. Adverse reactions, contrast dosage, test duration, invasiveness, hospital-stay, patient discomforts and accuracy were evaluated. Four potential donors (four female; mean age: 30.5 yr; mean BMI: 28.4) underwent both tests. Adverse reactions correlated to contrast agent used (90 mL CA, 150 mL 3-D-ACT) were not reported. CA required a hospitalization of 6 h as opposed to immediate discharge after the 3-D-ACT. The CA required the placement of transfemoral catheter and therefore greater patient discomfort than with 3-D-ACT. The 3-D-ACT arterial images were rated as equivalent to CA, however, 3-D-ACT venous images were rated better than the CA in all cases. CT-angiography with 3-D reconstruction is an acceptable method for vascular evaluation. When compared with routine angiography, it is less invasive, better tolerated and faster, but does require a significantly greater volume of venous contrast. 3-D-ACT also offers a better evaluation of the venous phase, and thus may become the test of choice to evaluate the vascular anatomies of LSBD candidates.