Indications for and limitations of portal vein embolization before major hepatic resection for hepatobiliary malignancy

Image-guided percutaneous strategies to improve the resectability of HCC: Portal vein embolization, liver venous deprivation, or radiation lobectomy?

Despite considerable advances in surgical technique, many patients with hepatic malignancies are not operative candidates due to projected inadequate hepatic function following resection. Consequently, the size of the future liver remnant (FLR) is an essential consideration when predicting a patient's likelihood of liver insufficiency following hepatectomy. Since its initial description 30 years ago, portal vein embolization has become the standard of care for augmenting the size and function of the FLR preoperatively. However, new minimally invasive techniques have been developed to improve surgical candidacy, chief among them liver venous deprivation and radiation lobectomy. The purpose of this review is to discuss the status of preoperative liver augmentation prior to resection of hepatocellular carcinoma with a focus on these three techniques, highlighting the distinctions between them and suggesting directions for future investigation.

Liver growth prediction in ALPPS - A multicenter analysis from the international ALPPS registry

BACKGROUND

While ALPPS triggers a fast liver hypertrophy, it is still unclear which factors matter most to achieve accelerated hypertrophy within a short period of time. The aim of the study was to identify patient-intrinsic factors related to the growth of the future liver remnant (FLR).

METHODS

This cohort study is composed of data derived from the International ALPPS Registry from November 2011 and October 2018. We analyse the influence of demographic, tumour type and perioperative data on the growth of the FLR. The volume of the FLR was calculated in millilitre and percentage using computed-tomography (CT) scans before and after stage 1, both according to Vauthey formula.

RESULTS

A total of 734 patients were included from 99 centres. The median sFLR at stage 1 and stage 2 was 0.23 (IQR, 0.18-0.28) and 0.39 (IQR: 0.31-0.46), respectively. The variables associated with a lower increase from sFLR1 to sFLR2 were age˃68 years (p = .02), height ˃1.76 m (p ˂ .01), weight ˃83 kg (p ˂ .01), BMI˃28 (p ˂ .01), male gender (p ˂ .01), antihypertensive therapy (p ˂ .01), operation time ˃370 minutes (p ˂ .01) and hospital stay˃14 days (p ˂ .01). The time required to reach sufficient volume for stage 2, male gender accounts 40.3% in group ˂7 days, compared with 50% of female, and female present 15.3% in group ˃14 days compared with 20.6% of male.

CONCLUSIONS

Height, weight, FLR size and gender could be the variables that most constantly influence both daily growths, the interstage increase and the standardized FLR before the second stage.

Improving the Safety of Major Resection for Hepatobiliary Malignancy: Portal Vein Embolization and Recent Innovations in Liver Regeneration Strategies

PURPOSE OF REVIEW

For three decades, portal vein embolization (PVE) has been the "gold-standard" strategy to hypertrophy the anticipated future liver remnant (FLR) in advance of major hepatectomy. During this time, CT volumetry was the most common method to preoperatively assess FLR quality and function and used to determine which patients are appropriate surgical candidates. This review provides the most up-to-date methods for preoperatively assessing the anticipated FLR and summarizes data from the currently available strategies used to induce FLR hypertrophy before surgery for hepatobiliary malignancy.

RECENT FINDINGS

Functional and physiological imaging is increasingly replacing standard CT volumetry as the method of choice for preoperative FLR assessment. PVE, associating liver partition and portal vein ligation, radiation lobectomy, and liver venous deprivation are all currently available techniques to hypertrophy the FLR. Each strategy has pros and cons based on tumor type, extent of resection, presence or absence of underlying liver disease, age, performance status, complication rates, and other factors. Numerous strategies can lead to FLR hypertrophy and improve the safety of major hepatectomy. Which is best has yet to be determined.

Portal vein embolization for induction of selective hepatic hypertrophy prior to major hepatectomy: rationale, techniques, outcomes and future directions

The ability to modulate the future liver remnant (FLR) is a key component of modern oncologic hepatobiliary surgery practice and has extended surgical candidacy for patients who may have been previously thought unable to survive liver resection. Multiple techniques have been developed to augment the FLR including portal vein embolization (PVE), associating liver partition and portal vein ligation (ALPPS), and the recently reported transhepatic liver venous deprivation (LVD). PVE is a well-established means to improve the safety of liver resection by redirecting blood flow to the FLR in an effort to selectively hypertrophy and ultimately improve functional reserve of the FLR. This article discusses the current practice of PVE with focus on summarizing the large number of published reports from which outcomes based practices have been developed. Both technical aspects of PVE including volumetry, approaches, and embolization agents; and clinical aspects of PVE including data supporting indications, and its role in conjunction with chemotherapy and transarterial embolization will be highlighted. PVE remains an important aspect of oncologic care; in large part due to the substantial foundation of information available demonstrating its clear clinical benefit for hepatic resection candidates with small anticipated FLRs.

Liver segmentation: practical tips

The liver segmentation system, described by Couinaud, is based on the identification of the three hepatic veins and the plane passing by the portal vein bifurcation. Nowadays, Couinaud's description is the most widely used classification since it is better suited for surgery and more accurate for the localisation and monitoring of intra-parenchymal lesions. Knowledge of the anatomy of the portal and venous system is therefore essential, as is knowledge of the variants resulting from changes occurring during the embryological development of the vitelline and umbilical veins. In this paper, the authors propose a straightforward systematisation of the liver in six steps using several additional anatomical points of reference. These points of reference are simple and quickly identifiable in any radiological examination with section imaging, in order to avoid any mistakes in daily practice. In fact, accurate description impacts on many diagnostic and therapeutic applications in interventional radiology and surgery. This description will allow better preparation for biopsy, portal vein embolisation, transjugular intrahepatic portosystemic shunt, tumour resection or partial hepatectomy for transplantation. Such advance planning will reduce intra- and postoperative difficulties and complications.

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.

Role of portal vein embolization in liver surgery: single centre experience in sixty-two patients

The extent of liver resection is limited by the residual functional reserve of the liver (FLR). The introduction of portal vein embolization (PVE), with the rationale of inducing hypertrophy of the FLR has significantly reduced morbidity and in particular the impact of postoperative liver failure (PLF). The objective of the study is to evaluate the feasibility and effectiveness of PVE in patients candidates to liver resections with high risk of PLF. Between January 2006 and December 2009, 62 patients suffering from primary or metastatic liver tumour, underwent PVE at the Department of Surgery-Liver Unit HSR. CT assessment of hepatic volume was performed in each patient, prior and 4 weeks after the procedure. The outcome was evaluated in terms of feasibility of surgery, FLR growth [calculated as: (FLR after PVE - FLR pre PVE) × 100/FLR pre PVE], morbidity and mortality associated with PVE and surgery. Of the 62 patients undergoing PVE, 6 (9.7%) did not benefit from surgery: of these, 4 showed spread of disease in the FLR at CT control, while in the remaining 2 adequate hypertrophy was not reached. The average volume of the FLR at the time of the procedure and after 4 weeks was 437.03 cc (±172.54) and 615.15 cc (± 187.49), respectively, with an average increase of 50.3% (±30.31). During the postoperative period, only 2 patients (3.2%) showed mild and transient signs of the PLF. The technique of PVE allows to performing, in an effective and safe way, major liver resections in patients with high risk of PLF.

Portal vein embolization: rationale, outcomes, controversies and future directions

Portal vein embolization (PVE) is now considered the standard of care to improve safety for patients undergoing extensive hepatectomy with an anticipated small future liver remnant (FLR). PVE is used to induce contralateral liver hypertrophy in preparation for major liver resection. Optimal patient selection is essential to maximize the clinical benefits of PVE. Computed tomography volumetry is used to calculate a standardized FLR and determine the need for preoperative PVE. Percutaneous PVE can be performed via the transhepatic ipsilateral or contralateral approaches, depending on operator preference. Several different embolic agents are available to the interventional radiologist, all with similar effectiveness in inducing hypertrophy. When an extended hepatectomy is planned, right PVE should include segment 4, in order to maximize FLR hypertrophy. Multiple studies have demonstrated the beneficial outcomes of PVE in both patients with healthy livers and with underlying liver diseases. Novel improvements to PVE should expand its scope to patients who were previously not candidates for the procedure.

Multi-disciplinary treatment for cholangiocellular carcinoma

Cholangiocarcinoma (CC) is rare malignant tumors composed of cells that resemble those of the biliary tract. It is notoriously difficult to diagnose, and is associated with a high mortality. Traditionally, CC is divided into intrahepatic and extraheaptic disease according to its location within the biliary tree. Intrahepatic cholangiocellular carcinoma (IH-CCC) or peripheral cholangiocellular carcinoma (CCC) appears within the second bifurcation of hepatic bile duct, and is the second most common primary liver cancer following hepatocellular carcinoma (HCC), IH-CCC or peripheral CCC often presents with advanced clinical features, and the cause for this cancer rise is still unclear. MRI, CT and PET provide useful diagnostic information in those patients. Surgical resection is the only chance for cure, with results depending on selected patients and careful surgical technique. Liver transplantation could offer long-term survival in selected patients when combined with chemotherapy. Chemotherapy, radiation therapy or combination therapies remain as the only treatment for inoperable patients. However, these are uniformly ineffective in patients’ survival.

Transarterial versus Transhepatic Portal Vein Embolization to Induce Selective Hepatic Hypertrophy: A Comparative Study in Swine

PURPOSE

Portal vein embolization (PVE) is used to induce liver hypertrophy for surgical candidates with marginal future liver remnant (FLR) volumes. We compared the feasibility, safety, and effectiveness of a transarterial approach for PVE (TA-PVE) with those of a transhepatic approach for PVE (TH-PVE) in a swine model.

MATERIALS AND METHODS

Ten experimental pigs (TA-PVE, n = 5; TH-PVE, n = 5) and six controls (TA, n = 3; TH, n = 3) were studied. For TA-PVE, a microcatheter was advanced into arteries supplying the left and left middle hepatic lobes. A 3 to 1 Ethiodol-ethanol mixture was infused into selected arteries to cross the arterioportal peribiliary plexus and remain within the portal veins (PVs). For TH-PVE, PVs in the same lobar distribution were embolized with 355- to 500-micro m polyvinyl alcohol particles and coils. Controls were similarly catheterized for saline infusion. Computed tomography with volumetry was performed before and 7, 14, 21, and 28 days after PVE to assess FLR hypertrophy (absolute FLR volume change and FLR/total liver volume [TLV]). Computed tomographic volumetry, laboratory data, and histopathology were compared between groups.

RESULTS

All procedures were technically successful. The increases in mean absolute FLR volume (TA-PVE, 148 +/- 84 cm(3); TH-PVE, 62 +/- 19 cm(3); P = .082), mean FLR hypertrophy (TA-PVE, 93.2%; TH-PVE, 48.4%; P = .178), and mean FLR/TLV (TA-PVE, 31.0%; TH-PVE, 16.2%; P = .130) from day 0 to day 28 between experimental groups were better for TA-PVE. Changes in laboratory data among all groups were minimal. Two complications occurred from TA-PVE (right gastric artery embolization [n = 2] without sequela) and two from TH-PVE (acute segmental right PV thrombosis [n = 1]; death 3 weeks after PVE of unknown cause [n = 1]).

CONCLUSIONS

Transarterial portal vein embolization is feasible, safe, and effective for inducing future liver remnant hypertrophy in swine and may represent an improvement over previously reported transhepatic portal vein embolization methods.

Portal vein embolization in preparation for major hepatic resection: evolution of a new standard of care

Portal vein (PV) embolization (PVE) is gaining acceptance in the preoperative management of patients selected for major hepatic resection. PVE redirects portal blood flow to the intended liver remnant to induce hypertrophy of the nondiseased portion of the liver and thereby reduce complications and shorten hospital stays after resection. This article reviews the rationale and existing literature on PVE, including the mechanisms of liver regeneration, the pathophysiology of PVE, the imaging techniques used to measure liver volumes and estimate functional hepatic reserve, and the technical aspects of PVE, including approaches and embolic agents used. In addition, the indications and contraindications for performing PVE in patients with and without chronic liver disease and the multidisciplinary approach required for the treatment of these complex cases are emphasized.

Transhepatic Ipsilateral Right Portal Vein Embolization Extended to Segment IV: Improving Hypertrophy and Resection Outcomes with Spherical Particles and Coils

PURPOSE

To analyze outcomes after right portal vein embolization extended to segment IV (right PVE + IV) before extended right hepatectomy, including liver hypertrophy, resection rates, and complications after embolization and resection, and to assess differences in outcomes with two different particulate embolic agents.

MATERIALS AND METHODS

Between 1998 and 2004, transhepatic ipsilateral right PVE + IV with particles and coils was performed in 44 patients with malignant hepatobiliary disease, including metastases (n = 24), biliary cancer (n = 14), and hepatocellular carcinoma (n = 6). Right PVE + IV was considered if the future liver remnant (FLR; segments II/III with or without I) was less than 25% of the total estimated liver volume (TELV). Tris-acryl microspheres (100-700 microm; n = 21) or polyvinyl alcohol (PVA) particles (355-1,000 microm; n = 23) were administered in a stepwise fashion. Smaller particles were used to occlude distal branches, followed by larger particles to occlude proximal branches until near-complete stasis. Coils were then placed in secondary portal branches. Computed tomographic volumetry was performed before and 3-4 weeks after right PVE + IV to assess FLR hypertrophy. Liver volumes and postembolization and postoperative outcomes were measured.

RESULTS

After right PVE + IV with PVA particles, FLR volume increased 45.5% +/- 40.9% and FLR/TELV ratio increased 6.9% +/- 5.6%. After right PVE + IV with tris-acryl microspheres, FLR volume increased 69.0% +/- 30.7% and FLR/TELV ratio increased 9.7% +/- 3.3%. Differences in FLR volume (P = .0011), FLR/TELV ratio (P = .027), and resection rates (P = .02) were statistically significant. Seventy-one percent of patients underwent extended right hepatectomy (86% after receiving tris-acryl microspheres, 57% after receiving PVA). Thirteen patients (29%) did not undergo resection (extrahepatic spread [n = 9], inadequate hypertrophy [n = 3], other reasons [n = 1]). No patient developed postembolization syndrome or progressive liver insufficiency after embolization or resection. One death after resection occurred as a result of sepsis and hemorrhage. Median hospital stays were 1 day after right PVE + IV and 7 days after resection.

CONCLUSION

Transhepatic ipsilateral right PVE + IV with use of particles and coils is a safe, effective method for inducing contralateral hypertrophy before extended right hepatectomy. Embolization with small spherical particles provides improved hypertrophy and resection rates compared with larger, nonspherical particles.