Percutaneous ablation of peribiliary tumors with irreversible electroporation

Irreversible Electroporation for Unresectable Hepatocellular Carcinoma: Initial Experience

PURPOSE

To evaluate the efficacy and safety of irreversible electroporation (IRE) in the treatment of unresectable hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

A retrospective study was conducted from September 2014 to June 2017. A total of 21 HCCs in 21 patients with cirrhosis were treated with IRE. There were eight subcapsular or exophytic, ten perivascular and three peribiliary tumors. The median tumor size was 26 mm (range 14-40 mm). The technical success of the procedure was recorded. Median follow-up, median time to local recurrence, median local tumor progression-free survival (PFS) and complications were recorded.

RESULTS

Technical success was achieved in all the patients. The median follow-up was 10 months (range 2-30 months). The median time to local recurrence and local tumor PFS were 4 months (range 3-4 months) and 7 months (range 3-30 months), respectively. The tumor-related factor that was significantly associated with local PFS was the size. Maximum tumor diameter < 25 mm was significantly associated with local tumor PFS (p = 0.045). Other parameters including tumor location, segmental portal vein thrombosis, baseline alpha-fetoprotein level and underlying etiology did not affect local tumor PFS. Complications were noted in nine patients and were classified as grades 1 and 2. No procedure-related mortality was encountered.

CONCLUSION

IRE is an effective treatment for ablation of small HCCs. Larger prospective studies with strict selection criteria will establish the safety and efficacy of IRE in the treatment of unresectable HCC in patients who cannot undergo thermal ablation.

Long-term survival after percutaneous irreversible electroporation of inoperable colorectal liver metastases

Background

For colorectal liver metastases (CRLM) that are not amenable to surgery or thermal ablation, irreversible electroporation (IRE) is a novel local treatment modality and additional option.

Methods

This study is a retrospective long-term follow-up of patients with CRLM who underwent IRE as salvage treatment.

Results

Of the 24 included patients, 18 (75.0%) were male, and the median age was 57 (range: 28-75) years. The mean time elapsed from diagnosis to IRE was 37.9±37.3 months. Mean overall survival was 26.5 months after IRE (range: 2.5-69.2 months) and 58.1 months after diagnosis (range: 14.8-180.1 months). One-, three-, and five-year survival rates after initial diagnosis were 100.0%, 79.2%, and 41.2%; after IRE, the respective survival rates were 79.1%, 25.0%, and 8.3%. There were no statistically significant differences detected in survival after IRE with respect to gender, age, T- or N-stage at the time of diagnosis, size of metastases subject to IRE, number of hepatic lesions, or time elapsed between IRE and diagnosis.

Conclusion

For nonresectable CRLM, long-term survival data emphasize the value of IRE as a new minimally invasive local therapeutic approach in multimodal palliative treatment, which is currently limited to systemic or regional therapies in this setting.

Navigation Systems for Treatment Planning and Execution of Percutaneous Irreversible Electroporation

The application of navigational systems has the potential to improve percutaneous interventions. The accuracy of ablation probe placement can be increased and radiation doses reduced. Two different types of systems can be distinguished, tracking systems and robotic systems. This review gives an overview of navigation devices for clinical application and summarizes first findings in the implementation of navigation in percutaneous interventions using irreversible electroporation. Because of the high number of navigation systems, this review focuses on commercially available ones.

Real-Time 3D Virtual Target Fluoroscopic Display for Challenging Hepatocellular Carcinoma Ablations Using Cone Beam CT

Three-dimensional virtual target fluoroscopic display is a new guidance tool that can facilitate challenging percutaneous ablation. The purpose of this study was to assess the feasibility, local efficacy, and safety of liver ablation assisted by three-dimensional virtual target fluoroscopic display. Sixty-seven hepatocellular carcinomas (mean diameter: 31 mm, range: 9-90 mm, 24 ≥ 30 mm, 16 of an infiltrative form) in 53 consecutive patients were ablated using irreversible electroporation (n = 39), multibipolar radiofrequency (n = 25), or microwave (n = 3) under a combination of ultrasound and three-dimensional virtual target fluoroscopic display guidance because the procedures were considered to be unfeasible under ultrasound alone. This guidance technology consisted of real-time fluoroscopic three-dimensional visualization of the tumor previously segmented from cone beam computed tomography images acquired at the start of the procedure. The results were assessed by cross-sectional imaging performed at 1 month and then every 3 months in the event of complete ablation. Factors associated with overall local tumor progression (initial treatment failure and subsequent local tumor progression) were assessed using a logistic regression model. Sixty-one (91%) tumors were completely ablated after 1 (n = 53) or 2 (n = 8) procedures. After a median follow-up of 12.75 months (1-23.2) of the 61 tumors displaying imaging characteristics consistent with complete ablation at 1 month, local tumor progression was observed in 9, so the overall local tumor progression rate was 22.3% (15 of 67). Under multivariate analysis, dome locations and infiltrative forms were associated with local tumor progression. No major complications occurred. Three-dimensional virtual target fluoroscopic display is a feasible and efficient image guidance tool to facilitate challenging ablations that are generally considered as infeasible using ultrasound alone.

Irreversible electroporation of malignant liver tumors: Effect on laboratory values

Liver cancer is often associated with chronic liver diseases. Treatment with percutaneous irreversible electroporation (IRE) may preserve liver function. In the present study, the clinical data of 29 patients with liver tumors between July 2015 and December 2016, all of whom underwent liver IRE at Fuda Cancer Hospital, Guangzhou, China was retrospectively reviewed. All the patients survived the treatment. Of the 29 patients, 7 were positive for hepatitis B, 15 had hepatocellular carcinoma (HCC) and 7 had pancreatic cancer with liver metastases. All patients survived IRE. Despite liver-protective treatment prior to IRE, the mean alanine transaminase (ALT) and aspartate transaminase (AST) levels were significantly elevated 1-2 days after IRE, to 540 and 712 U/l, respectively; however they had returned to the preoperative values by 2 weeks following IRE. Prior to IRE, the mean total bilirubin and direct bilirubin measurement levels were normal; however, 8-10 days after IRE, they had increased to 24 U/l and 12 µmol/l, respectively, and had returned back to the preoperative levels by 2 weeks after IRE. This first group included all patients. The result of the 4 subgroups of cancer patients demonstrated a variation between different measurement days and recovery with patients positive for the hepatitis B virus taking the longest duration to recover (17±3 days) meanwhile patients with pancreatic cancer with liver metastases took the shortest time to achieve recovery (10.78±2 days). The findings of the present study indicate that hepatic injury caused by IRE is transient and self-limiting in patients with liver tumors.

Electrochemotherapy of cholangiocellular carcinoma at hepatic hilum: A feasibility study

AIM

We evaluated feasibility, safety and efficacy of Electrochemotherapy (ECT) in a prospective series of patients with unresectable Perihilar-Cholangiocarcinoma (PHCCA).

PATIENTS AND METHODS

Five patients with PHCCA underwent ECT. Three patients underwent percutaneous ECT of a single PHCCA nodule. One patient underwent resection of a nodule in the IV segment and intraoperative ECT of a large PHCCA in the VIII segment. Another patient underwent percutaneous ECT of a large PHCCA recurrence after left lobectomy and RF ablation of a synchronous metastasis in the VI segment. ECT was performed under US guidance. Efficacy was evaluated by contrast-enhanced multiple-detector-computed-tomography (MDCT) 4 weeks after treatment. Follow-up entailed MDCT every 6 months thereafter.

RESULTS

No major complication occurred. Follow-up ranges from 10 to 30 months. Four weeks post-treatment CT showed complete response in 3 cases. These patients are still alive, and follow-up CT controls demonstrated no local or distant intrahepatic recurrences and no biliary duct dilation in 2 cases and local recurrence at 18 months follow-up control in 1 patient. In the remaining 2 cases, 4-weeks-post-treatment CT showed incomplete response (>90%). In these patients follow-up CT demonstrated local progression of the disease at 6 months. One of them had bilateral external biliary drainages and died because of tumor progression at 16-months-follow-up. The other patient, died at 10 months follow-up for cardiovascular failure not related to the hepatobiliary disease.

CONCLUSIONS

ECT is feasible, safe and effective therapy to improve prognosis and quality of life of patients with unresectable PHCCA.

Liver-Directed Therapies for Hepatocellular Carcinoma and Intrahepatic Cholangiocarcinoma

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (IHC) are primary liver cancers where all or most of the tumor burden is usually confined to the liver. Therefore, locoregional liver-directed therapies can provide an opportunity to control intrahepatic disease with minimal systemic side effects. The English medical literature and clinical trials were reviewed to provide a synopsis on the available liver-directed percutaneous therapies for HCC and IHC. Locoregional liver-directed therapies provide survival benefit for patients with HCC and IHC compared to best medical treatment and have lower comorbid risks compared to surgical resection. These treatment options should be considered, especially in patients with unresectable disease.

Reduction of Muscle Contractions during Irreversible Electroporation Therapy Using High-Frequency Bursts of Alternating Polarity Pulses: A Laboratory Investigation in an Ex Vivo Swine Model

PURPOSE

To compare the intensity of muscle contractions in irreversible electroporation (IRE) treatments when traditional IRE and high-frequency IRE (H-FIRE) waveforms are used in combination with a single applicator and distal grounding pad (A+GP) configuration.

MATERIALS AND METHODS

An ex vivo in situ porcine model was used to compare muscle contractions induced by traditional monopolar IRE waveforms vs high-frequency bipolar IRE waveforms. Pulses with voltages between 200 and 5,000 V were investigated, and muscle contractions were recorded by using accelerometers placed on or near the applicators.

RESULTS

H-FIRE waveforms reduced the intensity of muscle contractions in comparison with traditional monopolar IRE pulses. A high-energy burst of 2-μs alternating-polarity pulses energized for 200 μs at 4,500 V produced less intense muscle contractions than traditional IRE pulses, which were 25-100 μs in duration at 3,000 V.

CONCLUSIONS

H-FIRE appears to be an effective technique to mitigate the muscle contractions associated with traditional IRE pulses. This may enable the use of voltages greater than 3,000 V necessary for the creation of large ablations in vivo.

Ablation of hepatic malignant tumors with irreversible electroporation: A systematic review and meta-analysis of outcomes

Background

Irreversible electroporation (IRE) ablation is a new technique that is used to eliminate malignant tumors through nonthermal approaches.

Objective

The purpose of this review was to evaluate the efficiency of IRE for hepatic malignant tumors.

Methods

A systematic search was performed from PubMed, Embase, Web of science, Scopus and other potential literatures from references in relevant articles July 26th, 2016. Overall estimates of pooled standard mean difference (SMD) with 95% confidence interval (CI) were calculated for the changes of the pre- and post-IRE longest diameter, alkaline phosphatase (ALP), aspartate aminotransferase (AST) and serum total bilirubin levels. Sensitivity analysis and publication bias and were performed after the pooled analysis, and the quality of the included literatures was appraised using Newcastle-Ottawa Scale (NOS).

Results

We finally included 300 patients (mean age: 51 to 66.6 years; male: 182; female: 118) from 9 studies of hepatic malignant tumors. The meta-analysis showed that comparing with the initial values, the longest diameter of the tumors was significantly decreased at the last follow-up months after IRE. Furthermore, the ALP, AST and total bilirubin levels were increased at 1 day after IRE while returned to baseline at the last follow-up month. No risk of publication bias was found, and all literatures were assessed good quality according to NOS.

Conclusions

The pooled data indicated that IRE could be a minimal invasive and effective approach for patients who had preoperative poor liver function or those whose masses were in refractory locations where surgical resection was unsuitable.

Irreversible Electroporation in Hepatopancreaticobiliary Tumours

Hepatopancreaticobiliary tumours are often diagnosed at an advanced disease stage, in which encasement or invasion of local biliary or vascular structures has already occurred. Irreversible electroporation (IRE) is an image-guided tumour ablation technique that induces cell death by exposing the tumour to high-voltage electrical pulses. The cellular membrane is disrupted, while sparing the extracellular matrix of critical tubular structures. The preservation of tissue integrity makes IRE an attractive treatment option for tumours in the vicinity of vital structures such as splanchnic blood vessels and major bile ducts. This article reviews current data and discusses future trends of IRE for hepatopancreaticobiliary tumours.

Transmural ablation of the normal porcine common bile duct with catheter-directed irreversible electroporation is feasible and does not affect duct patency

BACKGROUND AND AIMS

The aim of this study was to evaluate the feasibility and early safety of catheter-directed irreversible electroporation (IRE) of the normal common bile duct (CBD) in swine.

METHODS

IRE (2000 V, 90 pulses, 100 μs pulse) was performed in the CBD of 6 Yorkshire pigs using a catheter electrode under endoscopic guidance. Ductal patency was assessed with immediate retrograde cholangiography and contrast-enhanced CT imaging at 1 or 7 days after treatment. Animals were killed at either 1 day (n = 4, 2 ablations/animal) or 7 days (n = 2, 1 ablation/animal) after treatment. The biliary tract was extracted en bloc and the length of the ablation along the CBD mucosa was measured. The depth of ablation was quantified using cross-sections of the treated CBD wall stained with hematoxylin and eosin. Single-sample hypothesis testing was performed to verify whether the depth of ablation in the CBD was a representative outcome of IRE treatment.

RESULTS

IRE of the CBD did not result in perforation or obstruction of the organ at 1 or 7 days after treatment. The length of ablation along the CBD mucosa was 17.27 ± 5.55 mm on day 1 samples, and transmural ablation of the CBD wall was a representative outcome of the treatment (7/8 samples, P < .05). Day 1 samples demonstrated loss of epithelium, transmural necrosis, with preservation of lumen integrity. Day 7 samples demonstrated re-epithelialization, with diffuse transmural fibrosis of the CBD wall. These findings were absent from sham tissue samples.

CONCLUSIONS

Intraluminal catheter-directed IRE is feasible and safe for full-thickness ablation of the normal porcine CBD without affecting lumen patency up to 1 week after treatment.

Catheter-based endobronchial electroporation is feasible for the focal treatment of peribronchial tumors

OBJECTIVE

To evaluate the feasibility of catheter-based endobronchial electroporation for the treatment of peribronchial tumors and assess the incidence of treatment-related adverse events.

METHODS

Cytotoxicity of electroporation with or without cisplatin or gefitinib was assessed in vitro with lung cancer and normal cell lines. A novel catheter was designed for endobronchial electroporation, and computer simulations were used to predict in vivo treatment effects. Electroporation with the test catheter was performed (2000 V, 70 pulses) in the main bronchus of 8 pigs at 11 locations. Computed tomography imaging was performed before they were killed at 4 hours (6 animals) or 4 weeks (2 animals) posttreatment. Treated airway and surrounding parenchyma were compared with sham treatment via gross and histopathology.

RESULTS

Significant cell death due to electroporation and increased cytotoxicity in combination with cisplatin or gefitinib were observed in cancer cells only (P < .05). Simulations predicted penetrative electroporation of peribronchial parenchyma without tissue heating. Electric pulse delivery in vivo induced transient venous and bronchial spasms that resolved without intervention. Cross-sectional measurement of electroporation effects on computed tomography (14.4 ± 1.4 by 10.5 ± 1.3 mm) and gross pathology (17.2 ± 3.0 by 8.8 ± 0.6 mm) were representative of values predicted by simulation (P < .001). Cell death due to irreversible electroporation was observed in bronchial and parenchymal tissue in acute tissue samples. Treated lung rapidly recovered from the effects of electroporation without change in bronchial patency at 4 weeks posttreatment.

CONCLUSIONS

Catheter-based endobronchial electroporation is a reproducible technique that can be used to treat peribronchial tumors in combination with cisplatin, without affecting patency of the treated bronchus.

Irreversible Electroporation: A Novel Ultrasound-guided Modality for Non-thermal Tumor Ablation

Ultrasound-guided tumor ablation techniques have been proven to be highly effective and minimally invasive in the treatment of many diseases. Traditional approaches to ablation include microwave and radiofrequency techniques, cryotherapy, and high-intensity focused ultrasound. However, these methods are prone to heat-sink effects that can diminish the effectiveness of treatment and damage adjacent structures, such as bile ducts, blood vessels, the gallbladder, or bowel. Irreversible electroporation (IRE) is a non-thermal ablation modality that induces cell apoptosis through the application of high-voltage current. IRE is not limited by many of the limitation which affects conventional tumor ablation techniques, and is particularly useful in treating sensitive areas of the body. The article reviews the basics of ultrasound-guided technology, including its clinical applications and effectiveness in the treatment of tumors.

Locoregional therapies in cholangiocarcinoma

Cholangiocarcinoma is a rare and aggressive malignancy of the biliary tract. Complete surgical resection can be curative, but the majority of patients are diagnosed with advanced disease and usually die within a year of diagnosis. Most deaths are attributable to local disease progression rather than distant metastases, supporting the use of locoregional therapies. There is evidence that locoregional therapies can provide local tumor control resulting in increased survival while avoiding some of the side effects of systemic treatments, increasing potential treatment options for patients who may be unsuitable for systemic palliative treatments. This review considers the evidence for locoregional therapies in cholangiocarcinoma, which can be classified into endoscopic, vascular, percutaneous and radiation oncological therapies. Current guidelines do not recommend the routine use of locoregional therapies due to a lack of prospective data, but the results of ongoing trials are likely to increase the evidence base and impact on clinical practice.

Ablation with irreversible electroporation in patients with advanced perihilar cholangiocarcinoma (ALPACA): a multicentre phase I/II feasibility study protocol

INTRODUCTION

The majority of patients with perihilar cholangiocarcinoma (PHC) has locally advanced disease or distant lymph node metastases on presentation or exploratory laparotomy, which makes them not eligible for resection. As the prognosis of patients with locally advanced PHC or lymph node metastases in the palliative setting is significantly better compared with patients with organ metastases, ablative therapies may be beneficial. Unfortunately, current ablative options are limited. Photodynamic therapy causes skin phototoxicity and thermal ablative methods, such as stereotactic body radiation therapy and radiofrequency ablation, which are affected by a heat/cold-sink effect when tumours are located close to vascular structures, such as the liver hilum. These limitations may be overcome by irreversible electroporation (IRE), a relatively new ablative method that is currently being studied in several other soft tissue tumours, such as hepatic and pancreatic tumours.

METHODS AND ANALYSIS

In this multicentre phase I/II safety and feasibility study, 20 patients with unresectable PHC due to vascular or distant lymph node involvement will undergo IRE. Ten patients who present with unresectable PHC will undergo CT-guided percutaneous IRE, whereas ultrasound-guided IRE will be performed in 10 patients with unresectable tumours detected at exploratory laparotomy. The primary outcome is the total number of clinically relevant complications (Common Terminology Criteria for Adverse Events, score of≥3) within 90 days. Secondary outcomes include quality of life, tumour response, metal stent patency and survival. Follow-up will be 2 years.

ETHICS AND DISSEMINATION

The protocol has been approved by the local ethics committees. Data and results will be submitted to a peer-reviewed journal.

CONCLUSION

The Ablation with irreversible eLectroportation in Patients with Advanced perihilar CholangiocarcinomA (ALPACA) study is designed to assess the feasibility of IRE for advanced PHC. The main purpose is to inform whether a follow-up trial to evaluate safety and effectiveness in a larger cohort would be feasible.

Midterm Safety and Efficacy of Irreversible Electroporation of Malignant Liver Tumors Located Close to Major Portal or Hepatic Veins

Purpose To investigate the efficacy and safety of irreversible electroporation (IRE) in the treatment of hepatic tumors not suitable for thermal ablation (radiofrequency ablation [RFA] or microwave ablation). Materials and Methods This was an institutional review board-approved prospective study in 29 patients (15 men, 14 women; mean age, 63 years ± 12 [standard deviation]) with 43 primary (n = 8) or secondary (n = 35) malignant liver tumors who underwent computed tomography (CT)-guided IRE. All target tumors were located immediately adjacent to major hepatic veins, portal veins, or both; thus, they were not considered suitable for RFA or microwave ablation. Patients underwent postinterventional CT and magnetic resonance (MR) imaging. Systematic follow-up MR imaging was performed for 24 months on average to assess complete ablation, intrahepatic tumor recurrence, and complications. The 95% confidence intervals (CIs) were determined for the rate of bile duct strictures, incomplete ablation, and tumor recurrence. Results Complete ablation was achieved in 40 (93%; 95% CI: 85, 100) of 43 target tumors, with a safety margin of 5-10 mm, and was confirmed at immediate postinterventional CT and MR imaging. In 13 (33%; 95% CI: 18, 47) of 40 completely ablated tumors, intrahepatic tumor recurrence was observed at 2-18 months. However, only two (15%; 95% CI: 0, 35) of these 13 tumors were observed within the ablation zone. In the remaining 11 (85%; 95% CI: 65, 100), tumor growth was observed alongside the needle tract. None of the two true local recurrences occurred at the site of the vessel. All adjacent vessels remained perfused at follow-up. Five (24%; 95% CI: 5, 39) of 21 patients with target tumors adjacent to portal veins developed mild to moderate cholestasis 2-6 weeks after IRE. Conclusion IRE is useful to avoid incomplete ablation secondary to heat-sink effects and damage to major blood vessels; however, needle tract seeding is observed in 26% of treated tumors, and IRE induces sufficient local heating to bile ducts in 24% of ablations. ^© RSNA, 2017.

Recurrence patterns following irreversible electroporation for hepatic malignancies

BACKGROUND

Irreversible electroporation (IRE) has emerged as a novel, safe ablative therapy for peri-vascular lesions. However, there remains a paucity of data on long-term outcomes.

METHODS

We identified patients who underwent open IRE (1/2011-6/2015) for primary and secondary hepatic malignancies. Local ablation-zone recurrence (LR) was determined by cross-sectional imaging. Cumulative incidence (CumI) of LR was calculated and a competing risks regression assessed factors associated with LR.

RESULTS

Forty patients had 77 lesions treated. The majority of lesions were of colorectal origin (74%). Median tumor size was 1.3 cm (range 0.5-6). Most patients (86%) had prior systemic therapy and 29% received systemic therapy following IRE. With a median follow-up of 25.7 months (range 4.5-58.8 months), 10 lesions in 9 patients recurred locally (CumI: 13.4%, 95%CI: 7.8-22.2%). Median estimated time to LR was not reached and no LR occurred after 19 months. Factors significantly associated with LR included ablation zone size (HR 1.58; 95%CI 1.12-2.23; P = 0.0093) and body mass index (HR 1.21 95%CI 1.10-1.34; P = 0.0001).

CONCLUSION

IRE LR rates were low after the treatment of well selected, small tumors. This technique is useful for lesions in anatomic locations precluding resection or thermal ablation.

Safety and Efficacy of Irreversible Electroporation for the Treatment of Hepatocellular Carcinoma Not Amenable to Thermal Ablation Techniques: A Retrospective Single-Center Case Series

Purpose To assess the safety and efficacy of irreversible electroporation (IRE) in the treatment of patients with inoperable hepatocellular carcinoma (HCC) who are ineligible for thermal ablative techniques. Materials and Methods This retrospective study was approved by an ethics review board, and the requirement to obtain informed written consent was waived. From March 2012 to June 2015, 58 patients (median age, 65.4 years; range 41.6-90 years) with cirrhosis received IRE for the treatment of 75 HCC tumors. The median tumor diameter was 24 mm (range, 6-90 mm). IRE was selected because of tumor location (48 patients) or the patient's poor general condition (10 patients). Treatment response was assessed with magnetic resonance (MR) imaging 1 month after treatment and every 3 months thereafter. Overall local tumor progression-free survival (PFS) per nodule (including initial treatment failures) was assessed by using the Kaplan-Meier method. The marginal Cox proportional hazards model was used to assess the factors associated with overall local tumor PFS. Complications were recorded and graded according to the Clavien-Dindo classification. Results Of 75 tumors, 58 (77.3%), 67 (89.3%), and 69 (92%) were completely ablated after one, two, and three IRE procedures, respectively. After a median follow-up of 9 months (range, 3 days to 31 months), the 6- and 12-month overall local tumor PFS rates for the 75 treated nodules were 87% (95% confidence interval [CI]: 77%, 93%) and 70% (95% CI: 56%, 81%), respectively. A preablative serum α-fetoprotein level higher than 200 ng/mL (hazard ratio: 9.94 [95% CI: 2.82, 35.06], P = .0004) was the only factor linked with overall local tumor PFS. Complications occurred in 11 of the 58 patients (19%) and were classified as grade I in three patients, grade II in five patients, grade IV in two patients, and grade V in one patient. The three (5.2%) complications classified as grade III or higher were liver failures occurring in patients with Child-Pugh class B disease; one led to death. Conclusion IRE offers safe, complete ablation of HCC tumors in patients with contraindications to other commonly used ablative techniques. ^© RSNA, 2017 Online supplemental material is available for this article.

New Approaches in Locoregional Therapies for Hepatocellular Carcinoma

PURPOSE

Hepatocellular carcinoma (HCC) represent actually the fifth most common cancer worldwide, with liver transplantation and hepatic resection who represent the standard of care of curative treatment. Unfortunately, not all patient could benefit of curative treatment. For such patients, locoregional or systemic therapies represent a valid option in order to achieve the best survival possible.

METHODS

A review of most interesting paper actually present in literature on locoregional treatment for nonresectable nontransplantable HCC was performed.

RESULTS

A detailed description on each different approach has been detailed in each chapter.

CONCLUSION

In case of nontransplantable and nonresectable HCC, locoregional treatment represent a valid alternative in management of this patients.

Bipolar Microsecond Pulses and Insulated Needle Electrodes for Reducing Muscle Contractions During Irreversible Electroporation

OBJECTIVE

To minimize the effect of muscle contractions during irreversible electroporation (IRE), this paper attempts to research the ablation effect and muscle contractions by applying high-frequency IRE (H-FIRE) ablation to liver tissue in vivo.

METHODS

An insulated needle electrode was produced by painting an insulating coating on the outer surface of the needle electrode tip. A series of experiments were conducted using insulated needle electrodes and traditional needle electrodes to apply H-FIRE pulses and traditional monopolar IRE pulses to rabbit liver tissues. The finite element model of the rabbit liver tissue was established to determine the lethal thresholds of H-FIRE in liver tissues. Muscle contractions were measured by an accelerometer.

RESULTS

With increased constitutive pulse width and pulse voltage, the ablation area and muscle contraction strength are also increased, which can be used to optimize the ablation parameters of H-FIRE. Under the same pulse parameters, the ablation areas are similar for the two types of electrodes, and the ablation region has a clear boundary. H-FIRE and insulated needle electrodes can mitigate the extent of muscle contractions. The lethal thresholds of H-FIRE in rabbit liver tissues were determined.

CONCLUSION

This paper describes the relationships between the ablation area, muscle contractions, and pulse parameters; the designed insulated needle electrodes can be used in IRE for reducing muscle contraction.

SIGNIFICANCE

The study provides guidance for treatment planning and reducing muscle contractions in the clinical application of H-FIRE.

Single-center nonrandomized clinical trial to assess the safety and efficacy of irreversible electroporation (IRE) ablation of liver tumors in humans: Short to mid-term results

INTRODUCTION

A single-center nonrandomized clinical trial was performed to assess the safety and efficacy of IRE ablation of liver tumors in humans.

METHODS

38 malignant liver tumors on 30 patients were treated with IRE between September 2011 and September 2014. Treatment was with curative intent, and the diagnoses were colorectal cancer with liver metastases (CRLM) (n = 23), hepatocellular carcinoma (HCC) (n = 8) and other metastasis (n = 7). Patients were selected when surgery, radiofrequency ablation (RFA) or microwave ablation (MWA) was not an option, and when they met inclusion criteria (tumor size < 3 cm, 1-2 tumors). Patients were followed-up at 1 and 6 months with a contrast-enhanced computed tomography (CE-CT), and contrast-enhanced ultrasound (CE-US) at 3 months.

RESULTS

Ablation success was defined as no evidence of residual tumor in the ablated area as confirmed by CE-CT and CE-US. At 3 months ablation success was 78.9%, and 65.8% at 6 months. There was no statistically significant difference between tumor volume (<5 cm³ vs >5 cm³, p = 0.518), and between diagnosis (CRLM vs HCC, p = 0.084) in terms of local recurrence. Complications were classified according to the standardized grading system of Society of Interventional Radiology (SIR). A minor complication occurred in six patients (20%), one patient (3.3%) suffered from a major complication (bile duct dilatation and stricture of the portal vein and bile duct). No mortalities occurred at 30 days.

CONCLUSIONS

IRE appears to be a safe treatment modality for a selected group of patients with liver tumors and offers high local tumor control at 3 and 6 months.

Management of unresectable intrahepatic cholangiocarcinoma: how do we decide among the various liver-directed treatments?

Intrahepatic cholangiocarcinoma often causes death due to obstruction of the biliary system or interruption of the vascular supply of the liver. This fact emphasizes the critical need for local tumor control in this disease. Successful local tumor control has traditionally been achievable through surgical resection for the small proportion of patients with operable tumors. Technological advances in radiation oncology and in interventional radiology have enabled the delivery of ablative radiation doses or other cytotoxic therapies for tumors in the liver. In some cases, this has translated into substantial prolongation of life for patients with this disease, but the indications for these different treatment options are still the subject of ongoing debate. Here, we review the technological advances and clinical studies that are changing the way intrahepatic cholangiocarcinoma is managed, and discuss ways to achieve individualized treatment of patients.

Thermal Ablation in the Management of Colorectal Cancer Patients with Oligometastatic Liver Disease

BACKGROUND

Surgical resection of limited colorectal liver disease improves long-term survival and can be curative in a subset of selected cases. Image-guided percutaneous ablation therapies have emerged as safe and effective alternative options for selected patients with unresectable colorectal liver metastases (CLM) that can be ablated with margins. Ablation causes focal destruction of tissue and has increasingly been shown to provide durable eradication of tumors.

METHODS

A selective review of literature was conducted in PubMed, focusing on recent studies reporting on the safety, efficacy, and long-term outcomes of percutaneous ablation modalities in the treatment of CLM. The present work gives an overview of the different ablation techniques, their current clinical indications, and reported outcomes from most recently published studies. The 'test of time' concept for using ablation as a first local therapy is also described.

RESULTS

There are several thermal ablative tools currently available, including radiofrequency ablation (RFA), microwave ablation, and cryoablation. Most data to date originated from the application of RFA. Adjuvant thermal ablation in the treatment of oligometastatic colon cancer liver disease offers improved oncologic outcomes. The ideal CLM amenable to percutaneous ablation is a solitary tumor with the largest diameter up to 3 cm that can be completely ablated with a sufficient margin. 5-year overall survival rates up to 70% after ablation of unresectable CLM have been reported. Pathologic confirmation of complete tumor necrosis with margins over 5 mm provides best long-term local tumor control by thermal ablation.

CONCLUSION

Current evidence suggests that percutaneous ablation as adjuvant to chemotherapy improves oncologic outcomes of patients with CLM. For small tumors that can be ablated completely with clear margins, percutaneous ablation may offer outcomes similar to those of surgery.

Bile Duct Injury after Irreversible Electroporation of Hepatic Malignancies: Evaluation of MR Imaging Findings and Laboratory Values

PURPOSE

To evaluate biliary complications after irreversible electroporation (IRE) of hepatic malignancies.

MATERIALS AND METHODS

In 24 patients (17 men; mean age, 59.3 y), bile ducts were located within a 1.0-cm radius of the ablation zone at subacute follow-up (ie, 1–3 d) after percutaneous IRE of 53 hepatic tumors (primary hepatic tumors, n = 14). MR imaging, conducted with a hepatocyte-specific contrast agent before and after treatment, was examined for evidence of bile duct injury. Serum bilirubin and alkaline phosphatase levels measured at subacute and short-term follow-up (ie, 1–2 mo after IRE) were analyzed for evidence of biliary injury. Correlations between bile duct injury and characteristics of patients, lesions, and ablation procedures were assessed by generalized linear models.

RESULTS

Fifty-five bile ducts were located within 1.0 cm of an ablation defect. Locations relative to the ablation area were as follows: 33 were encased, 14 were abutting, and 8 were located within a radius of 0.1–1.0 cm of the ablation zone. Subacute follow-up MR images showed 15 bile duct injuries (narrowing, n = 8; dilation, n = 7). At subacute follow-up, three patients showed transient abnormalities of laboratory values (bilirubin, 1.6–5.2 mg/dL). Short-term laboratory values were abnormal in one patient (increase in alkaline phosphatase of 533 U/L vs baseline) as a result of local tumor recurrence. Patient age (continuous, P = .026; < 65 y vs ≥ 65 y, P = .001) was independently associated with post-IRE bile duct injury.

CONCLUSIONS

Bile ducts adjacent to an IRE ablation area remain largely unaffected by this procedure.

Optimizing Irreversible Electroporation Ablation with a Bipolar Electrode

PURPOSE

To optimize single-insertion bipolar irreversible electroporation (IRE) by characterizing effects of electric parameters and controlling tissue electric properties in a porcine model.

MATERIALS AND METHODS

Single-insertion electrode bipolar IRE was performed in 28 in vivo pig livers (78 ablations). First, effects of voltage (2,700-3,000 V), number of pulses, repeated cycles (1-6 cycles), and pulse width (70-100 µs) were studied. Next, electric conductivity was altered by instillation of hypertonic and hypotonic fluids. Finally, effects of thermal stabilization were assessed using internal electrode cooling. Treatment effect was evaluated 2-3 hours after IRE. Dimensions were compared and subjected to statistical analysis.

RESULTS

Delivering 3,000 V at 70 µs for a single 90-pulse cycle yielded 3.8 cm ± 0.4 × 2.0 cm ± 0.3 of ablation. Applying 6 cycles of energy increased ablation to 4.5 cm ± 0.4 × 2.6 cm ± 0.3 (P < .001). Further increasing pulse lengths to 100 µs (6 cycles) increased ablation to 5.0 cm ± 0.4 × 2.9 cm ± 0.3 (P < .001) but resulted in electric spikes and system crashes in 40%-50% of cases. Increasing tissue electric conductivity via hypertonic solution instillation in surrounding tissues increased frequency of generator crashes, whereas continuous instillation of distilled water eliminated this arcing phenomenon but reduced ablation to 2.3 cm ± 0.1. Controlled instillation of distilled water when electric arcing was suspected from audible popping produced ablations of 5.3 cm ± 0.6 × 3.1 cm ±0.3 without crashes. Finally, 3.1 cm ± 0.1 short-axis ablation was achieved without system crashes with internal electrode perfusion at 37°C versus 2.3 cm ± 0.1 with 4°C-10°C perfusion (P < .001).

CONCLUSIONS

Bipolar IRE ablation zones can be increased with repetitive high voltage and greater pulse widths accompanied by either judicious instillation of hypotonic fluids or internal electrode perfusion to minimize unwanted electric arcing.

Irreversible electroporation: state of the art

The field of focal ablative therapy for the treatment of cancer is characterized by abundance of thermal ablative techniques that provide a minimally invasive treatment option in selected tumors. However, the unselective destruction inflicted by thermal ablation modalities can result in damage to vital structures in the vicinity of the tumor. Furthermore, the efficacy of thermal ablation intensity can be impaired due to thermal sink caused by large blood vessels in the proximity of the tumor. Irreversible electroporation (IRE) is a novel ablation modality based on the principle of electroporation or electropermeabilization, in which electric pulses are used to create nanoscale defects in the cell membrane. In theory, IRE has the potential of overcoming the aforementioned limitations of thermal ablation techniques. This review provides a description of the principle of IRE, combined with an overview of in vivo research performed to date in the liver, pancreas, kidney, and prostate.

Clinical outcomes for patients with liver-limited metastatic colorectal cancer: Arguing the case for specialist hepatobiliary multidisciplinary assessment

In patients with liver-limited metastatic colorectal cancer, hepatic resection can offer a significant survival benefit over systemic therapy alone. Specialist hepatobiliary multidisciplinary meetings are currently believed to provide the best forum to discuss the management for these patients. A retrospective analysis was undertaken of patients diagnosed with liver-limited metastatic colorectal cancer over 6 months within a cancer network in the United Kingdom. In addition, patients who were diagnosed but not referred to the hepatobiliary meeting were discussed within a virtual multi-disciplinary setting. Contributors were blinded and proposed management recorded. 159 newly diagnosed patients with liver-limited metastatic colorectal cancer were identified. 68 (43%) were referred at initial diagnosis and 38 (24%) referred following systemic treatment. 35 (51%) who were discussed at baseline underwent a subsequent hepatectomy or radiofrequency ablation, as did 18 (47%) patients referred after chemotherapy. Of the remaining 53 (33%) patients not referred, imaging was available for 31 (58%). Decisions regarding potential liver-directed therapy were discussed within a multi-disciplinary setting. 13 (42%) were identified as resectable or potentially resectable and 11 (36%) may have been suitable for a clinical trial. In reality, none of these 31 patients (100%) underwent surgery or ablation. Whilst the majority of patients with liver-limited metastatic colorectal cancer were referred appropriately, this study demonstrates that a significant number with potentially resectable disease are not being discussed at specialist meetings. A review of all diagnosed cases would ensure that an increased number of patients are offered hepatic resection or ablation.

Evidence-based medical oncology and interventional radiology paradigms for liver-dominant colorectal cancer metastases

Colorectal cancer metastasizes predictably, with liver predominance in most cases. Because liver involvement has been shown to be a major determinant of survival in this population, liver-directed therapies are increasingly considered even in cases where there is (limited) extrahepatic disease. Unfortunately, these patients carry a known risk of recurrence in the liver regardless of initial therapy choice. Therefore, there is a demand for minimally invasive, non-surgical, personalized cancer treatments to preserve quality of life in the induction, consolidation, and maintenance phases of cancer therapy. This report aims to review evidence-based conceptual, pharmacological, and technological paradigm shifts in parenteral and percutaneous treatment strategies as well as forthcoming evidence regarding next-generation systemic, locoregional, and local treatment approaches for this patient population.

Comparison of ablation defect on MR imaging with computer simulation estimated treatment zone following irreversible electroporation of patient prostate

To determine whether patient specific numerical simulations of irreversible electroporation (IRE) of the prostate correlates with the treatment effect seen on follow-up MR imaging. Computer models were created using intra-operative US images, post-treatment follow-up MR images and clinical data from six patients receiving IRE. Isoelectric contours drawn using simulation results were compared with MR imaging to estimate the energy threshold separating treated and untreated tissue. Simulation estimates of injury to the neurovascular bundle and rectum were compared with clinical follow-up and patient reported outcomes. At the electric field strength of 700 V/cm, simulation estimated electric field distribution was not different from the ablation defect seen on follow-up MR imaging (p = 0.43). Simulation predicted cross sectional area of treatment (mean 532.33 ± 142.32 mm(2)) corresponded well with the treatment zone seen on MR imaging (mean 540.16 ± 237.13 mm(2)). Simulation results did not suggest injury to the rectum or neurovascular bundle, matching clinical follow-up at 3 months. Computer simulation estimated zone of irreversible electroporation in the prostate at 700 V/cm was comparable to measurements made on follow-up MR imaging. Numerical simulation may aid treatment planning for irreversible electroporation of the prostate in patients.

Computed Tomography and Ultrasounds for the Follow-up of Hepatocellular Carcinoma Ablation: What You Need to Know

Image-guided tumor ablation provides curative treatment in properly selected patients or appropriate therapeutic options whenever surgical techniques are precluded. Tumor response assessment post ablation is important in determining treatment success and future therapy. Accurate interpretation of post-ablation imaging findings is crucial for therapeutic and follow-up strategies. Computed Tomography (CT) and Ultrasound (US) play important roles in patients' follow-up post liver thermal ablation therapies. Contrast-enhanced ultrasound (CEUS) can provide valuable information on the ablation effects faster and at a lower cost than computed tomography or magnetic resonance imaging. However, a disadvantage is that the technique cannot examine total liver parenchyma for disease progression as CT and Magnetic Resonance (MR) imaging can. Follow-up strategies for assessment of tumor response includes contrast enhanced multiphasic (non-contrast, arterial, portal, delayed phases) imaging with Computed Tomography at three, six, and 12 months post ablation session and annually ever since in order to prove sustained effectiveness of the ablation or detect progression.

Image-Guided Ablation of Malignant Liver Tumors: Recommendations for Clinical Validation of Novel Thermal and Non-Thermal Technologies - A Western Perspective

BACKGROUND

Image-guided ablation is used to treat patients with unresectable malignant hepatic tumors that are limited in number and size, especially hepatocellular carcinoma (HCC) and colorectal hepatic metastases. While radiofrequency ablation (RFA) has been the most popular technique, several alternate options for focal tissue destruction have recently attracted attention. These technologies appear to be able to overcome some specific limitations of RFA. Currently, there is no accepted algorithm for the use of the different techniques for image-guided ablation.

SUMMARY

A panel of physicians practicing in North America or Europe met to develop a set of recommendations aimed at providing directions for clinical validation of energy-based, thermal and non-thermal image-guided ablation technologies in the treatment of malignant liver tumors. The recommendations were developed through a critical appraisal of potential advantages and disadvantages of each ablation technology, based on experimental findings and available data, as well as on critical considerations for their clinical validation in hepatic tumor treatment from a Western perspective.

KEY MESSAGES

Significant variability appears to exist among the different equipment and devices within each type of technology. A comprehensive understanding of the data and a critical appraisal of the efficacy and safety profile of each ablation system is required. Clinical practice guidelines should include specific information of the recommended techniques and protocols instead of a generic indication of the technology.

Irreversible Electroporation

Irreversible electroporation (IRE) is a predominantly nonthermal ablative technology that uses high-voltage, low-energy DC current pulses to induce cell death. Thermal ablative technologies such as radiofrequency ablation, microwave ablation, and cryoablation have several applications in oncology but have limitations that have been established. IRE has shown promise to overcome some of these limitations. This article reviews the basics of the technology, patient selection, clinical applications, practical pointers, and the published data.

Diagnostic and therapeutic management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing health problem, representing the second cause of cancer-related mortality worldwide. The major risk factor for HCC is cirrhosis. In developing countries, viral hepatitis represent the major risk factor, whereas in developed countries, the epidemic of obesity, diabetes and nonalcoholic steatohepatitis contribute to the observed increase in HCC incidence. Cirrhotic patients are recommended to undergo HCC surveillance by abdominal ultrasounds at 6-mo intervals. The current diagnostic algorithms for HCC rely on typical radiological hallmarks in dynamic contrast-enhanced imaging, while the use of α-fetoprotein as an independent tool for HCC surveillance is not recommended by current guidelines due to its low sensitivity and specificity. Early diagnosis is crucial for curative treatments. Surgical resection, radiofrequency ablation and liver transplantation are considered the cornerstones of curative therapy, while for patients with more advanced HCC recommended options include sorafenib and trans-arterial chemo-embolization. A multidisciplinary team, consisting of hepatologists, surgeons, radiologists, oncologists and pathologists, is fundamental for a correct management. In this paper, we review the diagnostic and therapeutic management of HCC, with a focus on the most recent evidences and recommendations from guidelines.

Colorectal liver metastatic disease: efficacy of irreversible electroporation--a single-arm phase II clinical trial (COLDFIRE-2 trial)

Background

Irreversible electroporation (IRE) is a novel image-guided tumor ablation technique that has shown promise for the ablation of lesions in proximity to vital structures such as blood vessels and bile ducts. The primary aim of the COLDFIRE-2 trial is to investigate the efficacy of IRE for unresectable, centrally located colorectal liver metastases (CRLM). Secondary outcomes are safety, technical success, and the accuracy of contrast-enhanced (ce)CT and ¹⁸F-FDG PET-CT in the detection of local tumor progression (LTP).

Methods/design

In this single-arm, multicenter phase II clinical trial, twenty-nine patients with ¹⁸F-FDG PET-avid CRLM ≤ 3,5 cm will be prospectively included to undergo IRE of the respective lesion. All lesions must be unresectable and unsuitable for thermal ablation due to vicinity of vital structures. Technical success is based on ceMRI one day post-IRE. All complications related to the IRE procedure are registered. Follow-up consists of ¹⁸F-FDG PET-CT and 4-phase liver CT at 3-monthly intervals during the first year of follow-up. Treatment efficacy is defined as the percentage of tumors successfully eradicated 12 months after the initial IRE procedure based on clinical follow-up using both imaging modalities, tumor marker and (if available) histopathology. To determine the accuracy of ¹⁸F-FDG PET-CT and ceCT, both imaging modalities will be individually scored by two reviewers that are blinded for the final oncologic outcome.

Discussion

To date, patients with a central CRLM unsuitable for resection or thermal ablation have no curative treatment option and are given palliative chemotherapy. For these patients, IRE may prove a life-saving treatment option. The results of the proposed trial may represent an important step towards the implementation of IRE for central liver tumors in the clinical setting.

Trial registration

Trial registration number: NCT02082782.

Bursts of Bipolar Microsecond Pulses Inhibit Tumor Growth

Irreversible electroporation (IRE) is an emerging focal therapy which is demonstrating utility in the treatment of unresectable tumors where thermal ablation techniques are contraindicated. IRE uses ultra-short duration, high-intensity monopolar pulsed electric fields to permanently disrupt cell membranes within a well-defined volume. Though preliminary clinical results for IRE are promising, implementing IRE can be challenging due to the heterogeneous nature of tumor tissue and the unintended induction of muscle contractions. High-frequency IRE (H-FIRE), a new treatment modality which replaces the monopolar IRE pulses with a burst of bipolar pulses, has the potential to resolve these clinical challenges. We explored the pulse-duration space between 250 ns and 100 μs and determined the lethal electric field intensity for specific H-FIRE protocols using a 3D tumor mimic. Murine tumors were exposed to 120 bursts, each energized for 100 μs, containing individual pulses 1, 2, or 5 μs in duration. Tumor growth was significantly inhibited and all protocols were able to achieve complete regressions. The H-FIRE protocol substantially reduces muscle contractions and the therapy can be delivered without the need for a neuromuscular blockade. This work shows the potential for H-FIRE to be used as a focal therapy and merits its investigation in larger pre-clinical models.

Irreversible electroporation of hepatocellular carcinoma: preliminary report on the diagnostic accuracy of magnetic resonance, computer tomography, and contrast-enhanced ultrasound in evaluation of the ablated area

OBJECTIVE

Irreversible electroporation (IRE) is a new ablation modality. Our purpose was to describe the effectiveness and the safety of the treatment and to evaluate the magnetic resonance imaging (MRI), computed tomography (CT) and contrast-enhanced ultrasound (CEUS) diagnostic accuracy in HCC patients treated with IRE at 1-, 3-, and 6-month follow-up.

MATERIALS AND METHODS

In an 18-month period, we treated 24 HCC lesions in 20 patients unfit for surgery. MRI, CT and CEUS were performed before and one, 3 and 6 month after IRE. We employed the liver-specific contrast medium Primovist (gadolinium ethoxybenzyl dimeglumine) in MRI. After IRE the lesions were classified as responders or non-responders to the treatment according to the mRECIST and the complications were recorded. We evaluated the size, shape, signal intensity (T1-W, T2-W, and DWI) in MRI, dynamic contrast enhancement pattern for CEUS, CT and MRI and signal behavior during the liver-specific phase for MRI.

RESULTS

According to mRECIST, at 1 month MRI and CEUS showed a complete response (CR) in 91.7% of cases (22/24) tumors, while there was partial response (PR) in the remaining 2/24 (8.3%) treated nodules; in CT study all ablated zone appeared as necrotic (CR 100%). The residual viable tumor in MRI and in CEUS study had similar diameter (10 mm). No new HCC were identified from MRI, CT or CEUS. At 3 months MRI and CEUS showed the same results seen after 1 month from the treatment. Twenty-two necrotic lesions, and 2 residual tumors were found (CR = 91.7% and PD = 8.3%). In MRI study the two cases of residual tumor tissue had a diameter of 11 and 12 mm each. At CEUS the diameter of residual HCC was similar to the diameter at 1 month. CT showed 23 necrotic areas and one residual viable tissue in the treated zone, with a diameter of 10 mm (CR = 95.3% and PD = 4.7%). No new foci of HCC were identified from all imaging studies. At 6 months MRI, CEUS, and CT showed 22 necrotic lesions and 2 residual tumors in ablated zone (CR = 91.7% and PD = 8.3%). At MRI the diameters of the two residual viable HCCs were 12 and 14 mm, at CEUS the diameters were 11 and 12 mm, while at CT the diameters were 10 and 10 mm. No statistical difference was evaluated between CR, PR, PD percentage values for MRI, CT and CEUS (p value > 0.05 at Chi-square test). No major vascular complication was recorded after IRE. Six out of 20 patients (30%) showed a transient hepatic intensity difference (THID) area within the normal liver parenchyma adjacent to the treated lesions. Two of the 20 patients (10%) showed an absent concentration of liver-specific contrast medium around the ablation zone. Two patients developed complications, consisting in a peripheral arteriovenous shunt and a segmental dilation of the intrahepatic biliary ducts. We found no statistically significant difference in morphology, size (variation in the largest diameter), signal intensity in T1-weighted images, in T2-weighted images, in DWI and in the related map of the apparent diffusion coefficient (ADC), presence or absence of contrast enhanced during the arterial, portal, and late phase in MRI, CT, and CEUS, and signal characteristic during the liver-specific phase in MRI of the ablation zone at 1, 3, and 6 months.

CONCLUSION

IRE is a feasible, safe and efficient modality in the treatment of patients with non-resectable HCC. We had no major complication, even when the ablated lesion was adjacent to major branches of the portal vein. All images techniques showed similar accuracy during the follow-up at 1, 3, and 6 months in the assessment ablated zone.

Ablative and catheter-directed therapies for colorectal liver and lung metastases

Increasing data on treatment of liver metastases with locoregional therapies have solidified the expanding role of interventional radiologists (IRs) in the treatment of liver metastases from colorectal cancer. Ablative approaches such as radiofrequency ablation and microwave ablation have shown durable eradication of tumors. Catheter-directed therapies such as transarterial chemoembolization, drug-eluting beads, yttrium-90 radioembolization, and intra-arterial chemotherapy ports represent potential techniques for managing patients with unresectable liver metastases. Understanding the timing and role of these techniques in multidisciplinary care of patients is crucial. Implementation of IRs for consultation enables better integration of these therapies into patients' overall care.

Minimally Invasive Percutaneous Treatment of Small Renal Tumors with Irreversible Electroporation: A Single-Center Experience

PURPOSE

To evaluate whether irreversible electroporation (IRE) can be used as an ablation technique for small renal tumors (T1a cancers or small benign tumors) and to describe features after ablation on computed tomography (CT) or magnetic resonance (MR) imaging.

MATERIALS AND METHODS

In this retrospective study, 20 patients (mean age, 65 y ± 12.8 y) underwent CT-guided IRE of T1a renal carcinoma (n = 13) or small benign or indeterminate renal masses < 4 cm in size (n = 7). Mean tumor size was 2.2 cm ± 0.7. The ablation area was verified with contrast-enhanced imaging performed immediately after the procedure to determine technical success. Imaging was performed 6 weeks (20 of 20 patients), 6 months (15 of 20), and 12 months (6 of 20) after ablation. Medical records and CT/MR imaging features of all patients were reviewed for recurrence, symptoms, and complications after treatment.

RESULTS

Technical success was achieved in all patients (100%); there were no major procedure-related complications. Minor complications occurred in 7 patients, including self-limiting perinephric hematomas, pain difficult to control, and urinary retention. Mean procedure time was 2.0 hours ± 0.7. At 6 weeks, 2 patients required salvage therapy because of incomplete ablation. At 6 months, all 15 patients with imaging studies available had no evidence of recurrence. At 1 year, 1 patient (1 of 6) was noted to have experienced recurrence. CT/MR imaging after IRE ablation demonstrated an area of nonenhancement in the treatment zone that involuted over ~6 months.

CONCLUSIONS

Renal IRE appears to be a safe treatment for small renal tumors. Tumors treated with IRE demonstrated nonenhancement in the treatment zone with involution on follow-up CT/MR imaging.

Percutaneous ablation therapy of hepatocellular carcinoma with irreversible electroporation: MRI findings

OBJECTIVE

Irreversible electroporation is a new ablation modality. Our purpose was to describe the MRI findings after irreversible electroporation treatment of hepatocellular carcinoma (HCC).

SUBJECTS AND METHODS

In an 18-month period, we treated 24 HCC lesions in 20 patients who were not candidates for surgery. MRI was performed before and 1 month after irreversible electroporation. We used the liver-specific contrast medium gadoxetic acid. We evaluated the size, shape, signal intensity (T1-weighted, T2-weighted, and diffusion-weighted imaging), dynamic contrast enhancement pattern, and signal behavior during the liver-specific phase. Changes in the perilesional parenchyma, perfusion abnormalities, and complications were also recorded.

RESULTS

According to the modified Response Evaluation Criteria in Solid Tumors system, 22 of 24 lesions had a complete response, and two lesions showed a partial response and were retreated. The lesions showed a mean size increase of 10%, with a round or oval shape. On the T1-weighted images, we observed a hyperintense core and a hypointense rim. On the T2-weighted sequences, the signal was heterogeneously hypointense. On diffusion-weighted images, 83% of lesions showed restricted diffusion, with b values of 0-800 s/mm(2), whereas in 17% of the lesions, the signal was not clearly discernible for different b values. The apparent diffusion coefficient values did not show statistically significant differences between the baseline (800-1020 × 10(-3) mm(2)/s) and the reassessment after 1 month (900-1100 × 10(-3) mm(2)/s). The necrotic area did not show a signal increase after contrast material injection. Perfusion abnormalities, such as areas of transient hepatic intensity difference, were present in the tissue adjacent to six treated lesions. In two patients, a reduced or absent concentration of the contrast medium was observed during the liver-specific phase around the ablation zone. One patient had an arteriovenous shunt and another had biliary duct dilatation.

CONCLUSION

MRI detects characteristic morphologic and functional changes after irreversible electroporation treatment.

Update on treatment of liver metastases: focus on ablation therapies

There is substantial and growing interest in the use of local therapies to treat patients with metastatic cancer, especially those deemed to have "oligometastatic" disease. Much of the literature to date consists of reports on metastasectomy for liver and lung metastases. Non-surgical minimally or non-invasive treatments including thermal ablation, irreversible electroporation, and high-dose radiation therapy (stereotactic ablative radiation therapy) can also be used in the treatment of primary and secondary tumors, including in the treatment of liver metastases. In this review, we discuss the rationale for using these ablative treatments in the treatment of liver metastases including similarities and differences between them.

Niche Applications of Irreversible Electroporation

Irreversible electroporation (IRE) induces cell death by exposing it to high-voltage, low-energy DC current pulses. The mechanism of cell death and healing is a departure from the other existing technologies such as radiofrequency ablation, microwave ablation, and cryoablation. These thermal ablative technologies have several applications in oncology but have limitations that have also been established. IRE has shown promise to overcome some of these limitations and has enabled the use of an ablative technology in treating lesions close to the bile ducts and vasculature and in organs such as the pancreas. This review highlights some of the niche applications of IRE and the data so far.