Portal vein embolization: rationale, techniques, outcomes and novel strategies

Segments 4, 7, and 8 liver resection: A case report

Right superior resection (segments 7 and 8) is an uncommon resection for liver malignancies, with most of the literature limited to case reports and small series. Resection of segments 4, 7, and 8 has been reported in only a few cases. When the right hepatic vein is resected, venous reconstruction or identification of one or more right inferior hepatic veins is considered mandatory, to maintain segmentary function of segments 5 and 6. We present a case of liver resection of segments 4, 7, and 8 including the right and middle hepatic veins for symptomatic benign liver disease with no right hepatic vein reconstruction, nor a prominent right inferior hepatic vein(s). After the resection, there was no change in liver function tests, and the patient made an unremarkable recovery. Three months after the operation, partial atrophy of segments 5 and 6 with hypertrophy of the left lateral section was observed, while two and one half years after resection, the patient is asymptomatic. When right hepatic vein reconstruction would add unnecessary operative time, and there is low likelihood of the need for repeated resection, particularly when the hepatic vein is difficult to dissect, this approach can be safe and useful, while providing an adequate postoperative liver mass in the short-term to recover uneventfully from major liver resection.

Vascular Interventions in Oncology

Vascular interventions are an important and established tool in the management of the oncology patient. The goal of these procedures may be curative, palliative or adjunctive in nature. Some of the common vascular interventions used in oncology include transarterial embolisation or chemoembolisation, selective internal radiation therapy, chemosaturation, venous access lines, superior vena cava stenting and portal vein embolisation. We provide an overview of the principles, technology and approach of vascular techniques for tumour therapy in both the arterial and venous systems. Arterial interventions are currently mainly used in the management of hepatocellular carcinoma. Transarterial embolisation, chemoembolisation and selective internal radiation therapy deliver targeted catheter-delivered treatments with the aim of reducing tumour burden, controlling tumour growth or increasing survival in patients not eligible for transplantation. Chemosaturation is a regional chemotherapy technique that delivers high doses of chemotherapy directly to the liver via the hepatic artery, while reducing the risks of systemic effects. Venous interventions are more adjunctive in nature. Venous access lines are used to provide a means of delivering chemotherapy and other medications directly into the bloodstream. Superior vena cava stenting is a palliative procedure that is used to relieve symptoms of superior vena cava obstruction. Portal vein embolisation is a procedure that allows hypertrophy of a healthy portion of the liver in preparation for liver resection. Interventional radiology-led vascular interventions play an essential part of cancer management. These procedures are minimally invasive and provide a safe and effective adjunct to traditional cancer treatment methods. Appropriate work-up and discussion of each patient-specific problem in a multidisciplinary setting with interventional radiology is essential to provide optimum patient-centred care.

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.

Current Perspectives and Progress in Preoperative Portal Vein Embolization with Stem Cell Augmentation (PVESA)

Portal vein embolization with stem cell augmentation (PVESA) is an emerging approach for enhancing the growth of the liver segment that will remain after surgery (i.e., future liver remnant, FLR) in patients with liver cancer. Conventional portal vein embolization (PVE) aims to induce preoperative FLR growth, but it has a risk of failure in patients with underlying liver dysfunction and comorbid illnesses. PVESA combines PVE with stem cell therapy to potentially improve FLR size and function more effectively and efficiently. Various types of stem cells can help improve liver growth by secreting paracrine signals for hepatocyte growth or by transforming into hepatocytes. Mesenchymal stem cells (MSCs), unrestricted somatic stem cells, and small hepatocyte-like progenitor cells have been used to augment liver growth in preclinical animal models, while clinical studies have demonstrated the benefit of CD133 + bone marrow-derived MSCs and hematopoietic stem cells. These investigations have shown that PVESA is generally safe and enhances liver growth after PVE. However, optimizing the selection, collection, and application of stem cells remains crucial to maximize benefits and minimize risks. Additionally, advanced stem cell technologies, such as priming, genetic modification, and extracellular vesicle-based therapy, that could further enhance efficacy outcomes should be evaluated. Despite its potential, PVESA requires more investigations, particularly mechanistic studies that involve orthotopic animal models of liver cancer with concomitant liver injury as well as larger human trials.

Catheter-Directed Ionic Liquid Embolic Agent for Rapid Portal Vein Embolization, Segmentectomy, and Bile Duct Ablation

Embolic materials currently in use for portal vein embolization (PVE) do not treat the tumor, which poses a risk for tumor progression during the interval between PVE and surgical resection. Here, is developed an ionic-liquid-based embolic material (LEAD) for portal vein embolization, liver ablation, and drug delivery. LEAD is optimized and characterized for diffusivity, X-ray visibility, and cytotoxicity. In the porcine renal embolization model, LEAD delivered from the main renal artery reached vasculature down to 10 microns with uniform tissue ablation and delivery of small and large therapeutics. In non-survival and survival porcine experiments, successful PVE is achieved in minutes, leading to the expected chemical segmentectomy, and delivery of a large protein drug (i.e., Nivolumab) with LEAD. In cholangiocarcinoma mouse tumor models and in ex vivo human tumors, LEAD consistently achieved an effective ablation and wide drug distribution. Furthermore, various strains of drug-resistant patient-derived bacteria showed significant susceptibility to LEAD, suggesting that LEAD may also prevent infectious complications resulting from tissue ablation. With its capabilities to embolize, ablate, and deliver therapeutics, ease of use, and a high safety profile demonstrated in animal studies, LEAD offers a potential alternative to tumor ablation with or without PVE for FLR growth.

Assessment of Segmentary Hypertrophy of Future Remnant Liver after Liver Venous Deprivation: A Single-Center Study

Background: Liver venous deprivation (LVD) is a recent radiological technique that has shown promising results on Future Remnant Liver (FRL) hypertrophy. The aim of this retrospective study is to compare the segmentary hypertrophy of the FRL after LVD and after portal vein embolization (PVE). Methods: Patients undergoing PVE or LVD between April 2015 and April 2020 were included. The segmentary volumes (seg 4, seg2+3 and seg1) were assessed before and after the radiological procedure. Results: Forty-four patients were included: 26 undergoing PVE, 10 LVD and 8 eLVD. Volume gain of both segment 1 and segments 2+3 was significantly higher after LVD and eLVD than after PVE (segment 1: 27.33 ± 35.37 after PVE vs. 38.73% ± 13.47 after LVD and 79.13% ± 41.23 after eLVD, p = 0.0080; segments 2+3: 40.73% ± 40.53 after PVE vs. 45.02% ± 21.53 after LVD and 85.49% ± 45.51 after eLVD, p = 0.0137), while this was not true for segment 4. FRL hypertrophy was confirmed to be higher after LVD and eLVD than after PVE (33.53% ± 21.22 vs. 68.63% ± 42.03 vs. 28.11% ± 28.33, respectively, p = 0.0280). Conclusions: LVD and eLVD may induce greater hypertrophy of segment 1 and segments 2+3 when compared to PVE.

Recent advances in computerized imaging and its vital roles in liver disease diagnosis, preoperative planning, and interventional liver surgery: A review

The earliest and most accurate detection of the pathological manifestations of hepatic diseases ensures effective treatments and thus positive prognostic outcomes. In clinical settings, screening and determining the extent of a pathology are prominent factors in preparing remedial agents and administering appropriate therapeutic procedures. Moreover, in a patient undergoing liver resection, a realistic preoperative simulation of the subject-specific anatomy and physiology also plays a vital part in conducting initial assessments, making surgical decisions during the procedure, and anticipating postoperative results. Conventionally, various medical imaging modalities, e.g., computed tomography, magnetic resonance imaging, and positron emission tomography, have been employed to assist in these tasks. In fact, several standardized procedures, such as lesion detection and liver segmentation, are also incorporated into prominent commercial software packages. Thus far, most integrated software as a medical device typically involves tedious interactions from the physician, such as manual delineation and empirical adjustments, as per a given patient. With the rapid progress in digital health approaches, especially medical image analysis, a wide range of computer algorithms have been proposed to facilitate those procedures. They include pattern recognition of a liver, its periphery, and lesion, as well as pre- and postoperative simulations. Prior to clinical adoption, however, software must conform to regulatory requirements set by the governing agency, for instance, valid clinical association and analytical and clinical validation. Therefore, this paper provides a detailed account and discussion of the state-of-the-art methods for liver image analyses, visualization, and simulation in the literature. Emphasis is placed upon their concepts, algorithmic classifications, merits, limitations, clinical considerations, and future research trends.

Liver Transplantation for Colorectal Liver Metastases: Is It Appropriate?

Colorectal cancer with liver metastases is a condition with significant morbidity and mortality that affects many people around the world. Many treatments exist to target liver metastases, including surgical resection, chemotherapy, nonsurgical liver-directed therapies, and liver transplantation. The field of transplant oncology is emerging as a promising alternative to palliative chemotherapy alone in appropriately selected patients. Though few clinical trials have been completed to evaluate safety of liver transplant for colorectal cancer metastases, there are several ongoing trials to hopefully make transplant a viable option for more patients with limited options.

Case report: Portal vein ligation: lessons from patients with PRETEXT III hepatoblastoma in restoring future liver remnant before major hepatectomy and literature review

Background

We describe three cases involving three patients with PRETEXT III hepatoblastoma invading the hepatic hilum. After portal vein embolization, the patients underwent uncomplicated trisectionectomy.

Methods

Medical records between March 2016 and March 2021 were reviewed, and three patients were selected. A literature review of techniques for increasing future liver remnant in children diagnosed with hepatoblastoma was also conducted.

Results

All tumors involved the right lobe and hepatic hilum (PRETEXT III). After neoadjuvant chemotherapy, the tumor size decreased, but hilar involvement was unimproved. Right portal vein ligation (RPVL) was performed to increase the left lobe volume. Post-ligation, the remnant liver increased. Liver function was restored to normal levels within 5 days after the hepatectomy. All patients underwent two cycles of adjuvant chemotherapy without tumor recurrence.

Conclusions

RPVL can be safely performed before extended hepatic resection in children with a giant hepatoblastoma invading the hepatic hilum. The tumor was completely resected by securing a sufficient margin and increasing the residual liver volume with portal vein embolization. The patients recovered and underwent adjuvant chemotherapy without the deterioration of liver function.

Efficacy and safety of different options for liver regeneration of future liver remnant in patients with liver malignancies: a systematic review and network meta-analysis

BACKGROUND

Several treatments induce liver hypertrophy for patients with liver malignancies but insufficient future liver remnant (FLR). Herein, the aim of this study is to compare the efficacy and safety of existing surgical techniques using network meta-analysis (NMA).

METHODS

We searched PubMed, Web of Science, and Cochrane Library from databases for abstracts and full-text articles published from database inception through Feb 2022. The primary outcome was the efficacy of different procedures, including standardized FLR (sFLR) increase, time to hepatectomy, resection rate, and R0 resection margin. The secondary outcome was the safety of different treatments, including the rate of Clavien-Dindo≥3a and 90-day mortality.

RESULTS

Twenty-seven studies, including three randomized controlled trials (RCTs), three prospective trials (PTs), and twenty-one retrospective trials (RTs), and a total number of 2075 patients were recruited in this study. NMA demonstrated that the Associating Liver Partition and Portal vein ligation for Staged hepatectomy (ALPPS) had much higher sFLR increase when compared to portal vein embolization (PVE) (55.25%, 95% CI 45.27-65.24%), or liver venous deprivation(LVD) (43.26%, 95% CI 22.05-64.47%), or two-stage hepatectomy (TSH) (30.53%, 95% CI 16.84-44.21%), or portal vein ligation (PVL) (58.42%, 95% CI 37.62-79.23%). ALPPS showed significantly shorter time to hepatectomy when compared to PVE (-32.79d, 95% CI -42.92-22.66), or LVD (-34.02d, 95% CI -47.85-20.20), or TSH (-22.85d, 95% CI -30.97-14.72), or PVL (-43.37d, 95% CI -64.11-22.62); ALPPS was considered as the highest resection rate when compared to TSH (OR=6.09; 95% CI 2.76-13.41), or PVL (OR =3.52; 95% CI 1.16-10.72), or PVE (OR =4.12; 95% CI 2.19-7.77). ALPPS had comparable resection rate with LVD (OR =2.20; 95% CI 0.83-5.86). There was no significant difference between them when considering the R0 marge rate. ALPPS had a higher Clavien-Dindo≥3a complication rate and 90-day mortality compared to other treatments, although there were no significant differences between different procedures.

CONCLUSIONS

ALPPS demonstrated a higher regeneration rate, shorter time to hepatectomy, and higher resection rate than PVL, PVE, or TSH. There was no significant difference between them when considering the R0 marge rate. However, ALPPS developed the trend of higher Clavien-Dindo≥3a complication rate and 90-day mortality compared to other treatments.

Perioperative screening and management in elective complex hepatobiliary surgery

PURPOSE OF REVIEW

Preoperative optimization and structured evidence-based perioperative care of a patient undergoing complex hepatobiliary (HPB) surgery are essential components in their management. Apart from advances in surgical technique, these perioperative measures have resulted in substantial reductions in morbidity and mortality. There hence, remains a continued need to have evidence-based updation in their management algorithm to ensure optimal outcomes.

RECENT FINDINGS

We present an evidence-based overview of the preoperative screening, optimization and perioperative management of patients undergoing complex HPB surgery.

SUMMARY

Perioperative care of these fragile patients is an evidence-based dynamic process. Optimal patient management undergoing HPB surgery requires risk assessment and stratification, and meticulous attention to the correction of underlying conditions. Despite this, postoperative morbidity remains relatively high and requires a cohesive multidisciplinary approach to minimize complications.