Determining a minimal safe distance to prevent thermal injury to intrahepatic bile ducts in radiofrequency ablation of the liver: a study in dogs

Complications of Percutaneous Radiofrequency Ablation for Hepatocellular Carcinoma

Radiofrequency ablation (RFA) is a potentially curative treatment option for early Hepatocellular carcinoma. The RFA is considered safe with a relatively low incidence of complications ranging from 2%-7.9%. Though most of the complications are self-limiting, sometimes they can be life-threatening. The occurrence of the particular complication depends on various factors like tumour location and morphology, underlying disease and ablation technique. A detailed understanding of potential complications along with the associated risk factors will help to employ strategies to prevent them, identify them early and manage them when they occur. This article demonstrates various radiofrequency ablation-related complications and discusses the risk factors and technical strategies to minimise them and achieve complete ablation of the tumour.

Thermal ablation for hepatic tumors in high-risk locations

Thermal ablative techniques such as radiofrequency and microwave ablation are minimally invasive and cost-effective approaches that are currently being adopted as alternatives to surgical resection for primary and metastatic liver malignancies. However, they are considered to be relatively contraindicated for tumors in high-risk locations due to technical difficulties and a perceived increased risk of perioperative complications. Several techniques, including artificial ascites, non-touch multibipolar ablation, and laparoscopically assisted ablation, can be used to improve the outcomes of ablation for high-risk tumors. This review aims to provide a comprehensive summary of the techniques currently used to improve thermal ablation outcomes for high-risk liver tumors.

Comparative Oncology: Management of Hepatic Neoplasia in Humans and Dogs

Primary hepatic neoplasia is uncommonly reported in dogs. Hepatocellular carcinoma (HCC) is the most frequent neoplasia identified in dogs and considerable effort has been committed towards identifying definitive and palliative treatment options. HCC is well recognized in humans as a sequelae of liver disease such as hepatitis or cirrhosis, while in dogs a similar link has failed to be fully elucidated. Management of HCC in people may be curative or palliative dependent on staging and transplant eligibility. Despite differences in etiology, there is substantial similarity between treatment options for liver neoplasia in human and veterinary medicine. The below summary provides a comparative discussion regarding hepatic neoplasia in dogs and people with a specific focus on HCC. Diagnosis as well as descriptions of the myriad treatment options will be reviewed.

Advances in the interventional therapy of hepatocellular carcinoma originating from the caudate lobe

Hepatocellular carcinoma originating from the caudate lobe, also known as segment I hepatocellular carcinoma, is difficult to treat because of its special location, complex vascular supply, and the proximity of important vessels, bile ducts, and organs. This research is conducted to examine the efficacy and safety of interventional therapy for hepatocellular carcinoma in the caudate lobe.

Conclusion

Superselective chemoembolization and ablation techniques for the treatment of caudate lobe hepatocellular carcinoma still need to be improved. The combination of multiple interventional methods and the application of multiple imaging techniques can improve the effectiveness and safety of interventional therapy for hepatocellular carcinoma in the caudate lobe. Multidisciplinary treatment is also essential to improve the prognosis of patients with caudate lobe hepatocellular carcinoma.

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The anatomical characteristics of the arteries in the caudate lobe hepatocellular carcinoma remains an important factor restricting the success rate of superselective transcatheter arterial chemoembolization.

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The application of multiple imaging techniques may improve the effectiveness and safety of interventional therapy.

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The combination of multiple interventional methods has more advantages than disadvantages.

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Multidisciplinary treatment is increasingly becoming a trend in the treatment of caudate lobe hepatocellular carcinoma.

Irreversible Electroporation to Treat Unresectable Colorectal Liver Metastases (COLDFIRE-2): A Phase II, Two-Center, Single-Arm Clinical Trial

Background Irreversible electroporation (IRE), an ablative technique that uses high-voltage electrical pulses, has shown promise for eradicating tumors near critical structures, including blood vessels and bile ducts. Purpose To investigate the efficacy and safety of IRE for colorectal liver metastases (CRLMs) unsuitable for resection or thermal ablation because of proximity to critical structures and for further systemically administered treatments. Materials and Methods Between June 2014 and November 2018, participants with fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG) PET-avid CRLMs measuring 5.0 cm or smaller, unsuitable for partial hepatectomy and thermal ablation, underwent percutaneous or open IRE (ClinicalTrials.gov identifier: NCT02082782). Follow-up included tumor marker assessment and ¹⁸F-FDG PET/CT imaging. For the primary end point to be met, at least 50% of treated participants had to be alive without local tumor progression (LTP) at 12 months, defined as LTP-free survival. Secondary aims were safety, technical success, local control allowing for repeat procedures, disease-free status, and overall survival. Results A total of 51 participants (median age, 67 years [interquartile range, 62-75 years]; 37 men) underwent IRE. Of these 51 participants, 50 with a total of 76 CRLMs (median tumor size, 2.2 cm; range, 0.5-5.4 cm) were successfully treated in 62 procedures; in one participant, treatment was stopped prematurely because of pulse-induced cardiac arrhythmia. With a per-participant 1-year LTP-free survival of 68% (95% CI: 59, 84) according to competing risk analysis, the primary end point was met. Local control following repeat procedures was achieved in 74% of participants (37 of 50). Median overall survival from first IRE was 2.7 years (95% CI: 1.6, 3.8). Twenty-three participants experienced a total of 34 adverse events in 25 of the 62 procedures (overall complication rate, 40%). One participant (2%), who had an infected biloma after IRE, died fewer than 90 days after the procedure (grade 5 adverse event). Conclusion Irreversible electroporation was effective and relatively safe for colorectal liver metastases 5.0 cm or smaller that were unsuitable for partial hepatectomy, thermal ablation, or further systemic treatment. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Goldberg in this issue.

Thermal Processes in Bile Ducts During Laparoscopic Cholecystectomy with Monopolar Instruments. Experimental Study Using Real-Time Intraluminal and Surface Thermography

Introduction. A significant rate of complications during laparoscopic cholecystectomy (LC) occurs due to thermal injury caused by monopolar electrosurgery (MES) equipment. Most of them manifest weeks and months after surgery with the common bile duct (CBD) and large duodenal papilla strictures, some in the early postoperative period with bile leaks. Objective. To study thermal processes occurring in the lumen and on the surface of the bile ducts during monopolar coagulation in a porcine model of LC. Methods. The temperature of the bile ducts was measured using instrumentation consisted of biliary stent with temperature sensors, which was inserted in the porcine CBD, signal amplifier, and current sense transformer. Surface temperature was measured with a scientific grade thermal camera. Cholecystectomy was performed using a standard "critical view of safety" (CVS) approach with 5 mm monopolar laparoscopic instruments. Results. Application of MES caused significant tissue heating. Lateral thermal spread and the rate of tissue heating depended on the duration of energy application and the initial tissue temperature. In 5 out of 6 experiments, the intraluminal temperature rose up to the critical threshold, and the exposure time ranged from 54 to 560 seconds. A sensor positioned at the papilla site was heated in all the experiments but still below the cell damage inducing threshold. The analysis of thermographic charts revealed the presence of the "current channeling" effect and the pedicle effect. Conclusion. There is a possibility of a direct and delayed thermal injury to the bile ducts during LC.

Risk factors of intrahepatic biloma and secondary infection after thermal ablation for malignant hepatic tumors

Objective: This study aimed to evaluate the risk factors of biloma formation and secondary infection after thermal ablation for malignant hepatic tumors. Patients and methods: A total of 58 patients with 68 bilomas after thermal ablation were recruited as the complication group, and 61 patients with 72 lesions without major complications were selected randomly as the control group. The potential risk factors for biloma formation were analyzed with the chi-square test and multivariate logistic regression analysis. To determine the optimum management method for biloma, patients with secondary infection were included for the subgroup analysis of risk factors. Results: A history of transcatheter arterial chemoembolization (TACE) treatment (odds ratio [OR]: 3.606, 95% confidence interval [CI]: 1.165-11.156, p = .026) and tumor location (OR: 37.734, 95% CI: 13.058-109.034, p = .000) were independent predictors of biloma formation. Among the 58 patients with biloma, 49 (84.5%) showed no symptoms (i.e., the asymptomatic group), while the remaining 9 (15.5%) developed symptoms related to secondary infections (i.e., the symptomatic group). There were significant differences in the history of biliary manipulation (p = .031) between the symptomatic and asymptomatic groups. Conclusion: A history of TACE treatment and the distance from the biliary tract were independent predictors of biloma formation after thermal ablation. Therefore, protecting the bile duct (i.e., cooling of the bile duct and combing thermal ablation with chemical ablation) should be considered for high-risk patients. Moreover, active monitoring and management should be performed for patients with bilomas who underwent biliary surgery before.

No-touch radiofrequency ablation using multiple electrodes: An in vivo comparison study of switching monopolar versus switching bipolar modes in porcine livers

Objective

To evaluate the in vivo technical feasibility, efficiency, and safety of switching bipolar (SB) and switching monopolar (SM) radiofrequency ablation (RFA) as a no-touch ablation technique in the porcine liver.

Materials and methods

The animal care and use committee approved this animal study and 16 pigs were used in two independent experiments. In the first experiment, RFA was performed on 2-cm tumor mimickers in the liver using a no-touch technique in the SM mode (2 groups, SM1: 10 minutes, n = 10; SM2: 15 minutes, n = 10) and SB-mode (1 group, SB: 10 minutes, n = 10). The technical success with sufficient safety margins, creation of confluent necrosis, ablation size, and distance between the electrode and ablation zone margin (DEM), were compared between groups. In the second experiment, thermal injury to the adjacent anatomic organs was compared between SM-RFA (15 minutes, n = 13) and SB-RFA modes (10 minutes, n = 13).

Results

The rates of the technical success and the creation of confluent necrosis were higher in the SB group than in the SM1 groups (100% vs. 60% and 90% vs. 40%, both p < 0.05). The ablation volume in the SM2 group was significantly larger than that in the SB group (59.2±18.7 cm³ vs. 39.8±9.7 cm^3,p < 0.05), and the DEM in the SM2 group was also larger than that in the SB group (1.39±0.21 cm vs. 1.07±0.10 cm, p < 0.05). In the second experiment, the incidence of thermal injury to the adjacent organs and tissues in the SB group (23.1%, 3/13) was significantly lower than that in the SM group (69.2%, 8/13) (p = 0.021).

Conclusion

SB-RFA was more advantageous for a no-touch technique for liver tumors, showing the potential of a better safety profile than SM-RFA.

Percutaneous electrochemotherapy in the treatment of portal vein tumor thrombosis at hepatic hilum in patients with hepatocellular carcinoma in cirrhosis: A feasibility study

AIM

To treated with electrochemotherapy (ECT) a prospective case series of patients with liver cirrhosis and Vp3-Vp4- portal vein tumor thrombus (PVTT) from hepatocellular carcinoma (HCC), in order to evaluate the feasibility, safety and efficacy of this new non thermal ablative technique in those patients.

METHODS

Six patients (5 males and 1 female), aged 61-85 years (mean age, 70 years), four in Child-Pugh A and two in Child-Pugh B class, entered our study series. All patients were studied with three-phase computed tomography (CT), contrast enhanced ultrasound (CEUS) and ultrasound-guided percutaneous biopsy of the thrombus before ECT. All patients underwent ECT treatment (Cliniporator Vitae^®, IGEA SpA, Carpi, Modena, Italy) of Vp3-Vp4 PVTT in a single session. At the end of the procedure a post-treatment biopsy of the thrombus was performed. Scheduled follow-up in all patients entailed: CEUS within 24 h after treatment; triphasic contrast-enhanced CT and CEUS at 3 mo after treatment and every six months thereafter.

RESULTS

Post-treatment CEUS showed complete absence of enhancement of the treated thrombus in all cases. Post-treatment biopsy showed apoptosis and necrosis of tumor cells in all cases. The follow-up ranged from 9 to 20 mo (median, 14 mo). In 2 patients, the follow-up CT and CEUS demonstrated complete patency of the treated portal vein. Other 3 patients showed a persistent avascular non-tumoral shrinked thrombus at CEUS and CT during follow-up. No local recurrence was observed at follow-up CT and CEUS in 5/6 patients. One patient was lost to follow-up because of death from gastrointestinal hemorrage 5 wk after ECT.

CONCLUSION

In patients with cirrhosis, ECT seems effective and safe for curative treatment of Vp3-Vp4 PVTT from HCC.

Ultrasound-Guided Percutaneous Radiofrequency Ablation of Liver Tumors: How We Do It Safely and Completely

Ultrasound-guided percutaneous radiofrequency (RF) ablation has become one of the most promising local cancer therapies for both resectable and nonresectable hepatic tumors. Although RF ablation is a safe and effective technique for the treatment of liver tumors, the outcome of treatment can be closely related to the location and shape of the tumors. There may be difficulties with RF ablation of tumors that are adjacent to large vessels or extrahepatic heat-vulnerable organs and tumors in the caudate lobe, possibly resulting in major complications or treatment failure. Thus, a number of strategies have been developed to overcome these challenges, which include artificial ascites, needle track ablation, fusion imaging guidance, parallel targeting, bypass targeting, etc. Operators need to use the right strategy in the right situation to avoid the possibility of complications and incomplete thermal tissue destruction; with the right strategy, RF ablation can be performed successfully, even for hepatic tumors in high-risk locations. This article offers technical strategies that can be used to effectively perform RF ablation as well as to minimize possible complications related to the procedure with representative cases and schematic illustrations.

Radiofrequency ablation of hepatocellular carcinoma in elderly patients fitting the Milan criteria: a single centre with 13 years experience

PURPOSE

The aim of this study was to evaluate the safety and outcomes of radiofrequency ablation (RFA) in treating elderly patients with hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

This was a retrospective analysis of 391 patients with HCC fitting the Milan criteria and treated with RFA for the first time from 1999 to 2012 at the Southwest Hospital, China. The patients were divided into two groups, an elderly group (age ≥70 years, n = 102) and a non-elderly group (age <70 years, n = 289). Long-term outcomes were assessed on all patients and survival rates were calculated.

RESULTS

The overall survival rates of the two groups differed significantly. The recurrence-free survival rates of the two groups did not differ significantly. There was no significant difference between the two groups. Excluding comorbid diseases related deaths, the overall survival rates of the two groups did not differ significantly.

CONCLUSIONS

The safety and outcomes of RFA in treating early HCC were similar among elderly and non-elderly patients. Co-morbid diseases, such as cardiovascular disease and respiratory disease, rather than HCC or liver diseases, contributed to the relatively low overall survival rate found in elderly patients.

Science to practice: Can we turn the undesired heating effects of MR imaging into effective cancer therapies?

In this basic research study, Zhang et al created and report on a clever magnetic resonance (MR)-guided radiofrequency (RF) system that enables focal hyperthermic heating, targeting, and visualization for the treatment of cholangiocarcinoma. The key novelty is creating localized MR-induced heating around a metallic guidewire, which they subsequently demonstrate can be successfully combined with chemotherapy to (a) reduce cell proliferation in vitro, (b) decrease tumor growth in mouse xenografts, and (c) increase biliary uptake of chemotherapeutic drugs in swine. An added benefit of the system is using the wire as an intraluminal receiver antenna to improve the resolution of intraprocedural imaging guidance.