No-Touch Multi-bipolar Radiofrequency Ablation for the Treatment of Subcapsular Hepatocellular Carcinoma ≤ 5 cm Not Puncturable via the Non-tumorous Liver Parenchyma

Clinical Analysis of Microwave Ablation Combined with Decompression and Pedicle Screw Fixation in the Treatment of Spinal Metastases

OBJECTIVES

There is still controversy over the choice of treatment for end-stage spinal metastases. With the continuous development of microwave technology in spinal tumors, related studies have reported that microwave combined with techniques such as pedicle screw fixation and percutaneous vertebroplasty can achieve the purpose of tumor ablation, relieving spinal cord compression, enhancing spinal stability, effectively relieving pain, and reducing recurrence rates. This study aimed to analyze the effectiveness of microwave ablation combined with decompression and pedicle screw fixation in the palliative management of spinal metastases with pathological fractures.

METHODS

This retrospective study enrolled 82 patients with spinal metastases and pathological fractures treated between January 2016 and July 2020, with 44 patients undergoing pedicle screw fixation along with laminectomy (fixation group) and the remaining 38 receiving microwave ablation in addition to the treatment provided to group fixation (MWA group). Before surgery, all patients underwent pain assessment using the visual analogue scale (VAS) and evaluation of spinal cord injury using the Frankel classification. After surgery, the patients' prognoses were assessed using the Tomita score, modified Tokuhashi score system, and progression-free survival. Additionally, we compared operative time and blood loss between the two groups. Survival analysis utilized the Kaplan-Meier method with a log-rank test for group comparisons. Paired t-tests and the Mann-Whitney U test were applied to metric and non-normally distributed data, respectively. Neurological function improvement across groups was evaluated using the χ2 test.

RESULTS

All patients were followed up for a median duration of 18 and 20 months in the fixation and MWA groups, respectively, with follow-up periods ranging from 6 to 36 months. Statistically significant reductions in postoperative VAS scores were observed in all patients compared with their preoperative scores. The MWA group exhibited reduced blood loss (t = 2.74, p = 0.01), lower VAS scores at the 1- and 3-month follow-ups (t = 2.34, P = 0.02; t = 2.83, p = 0.006), and longer progression-free survival than the fixation group (p = 0.03). Although the operation times in the MWA group were longer than those in the fixation group, this difference was not statistically significant (t = 6.06, p = 0.12). No statistically significant differences were found regarding improvements in spinal cord function between the two groups (p = 0.77).

CONCLUSION

Compared with decompression and pedicle screw fixation for treating spinal metastases with pathological fractures, microwave ablation combined with decompression and pedicle screw fixation showed better outcomes in terms of pain control, longer progression-free survival, and lower blood loss without increasing operative time, which has favorable implications for clinical practice.

Anatomical thermal ablation as an alternative to surgical resection for subcapsular hepatocellular carcinoma

PURPOSE

To simulate the advantages of anatomical resection, a new strategy of anatomical thermal ablation was proposed. The objective of this study was to evaluate the clinical value of anatomical thermal ablation (ATA) to treat subcapsular hepatocellular carcinoma by comparing it with anatomical resection (AR) and non-anatomical resection (NAR).

METHODS

This retrospective cohort study enrolled hepatocellular carcinoma patients with subcapsular tumor diameter ≤ 50 mm treated by ATA or surgical resection at our center from October 2015 to December 2018. ATA features ablation of the Glisson capsule, ablation of the liver parenchyma between the tumor and hepatic veins or inferior vena cava and then puncture from the surrounding part to the central part of the tumor. Outcome parameters were compared.

RESULTS

Seventy-six patients were grouped into ATA group, 95 patients into AR group and 41 patients into NAR group. The 1-, 2-, and 3-year local recurrence rates were 0.0%, 0.0%, 0.0% for ATA group, 0.0%, 1.4%, 1.4% for the AR group and 0.0%, 0.0%, and 0.0% for the NAR group, respectively (P = 0.449). The 1-, 2-, and 3-year progression-free survival rates were 90.6%, 80.9%, and 74.6% for ATA group, 91.5%, 80.2%, and 80.2% for the AR group and 82.9%, 73.8%, and 73.8% for the NAR group, respectively (P = 0.608). The 1-, 2-, and 3-year overall survival rates were 100.0%, 95.2%, and 95.2% for the ATA group, 96.8%, 95.6%, and 95.6% for the AR group and 97.6%, 95.0%, and 95.0% for the NAR group, respectively (P = 0.970). No difference was found in major complication rate among these groups (P = 0.091).

CONCLUSION

For subcapsular hepatocellular carcinoma, ATA could be an alternative to surgical resection with its comparable treatment effect and safety.

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.

Long-term outcome and eligibility of radiofrequency ablation for hepatocellular carcinoma over 3.0 cm in diameter

Percutaneous radiofrequency ablation (RFA) is effective for the treatment of small hepatocellular carcinoma (HCC) with a diameter ≤ 3.0 cm. The present study aimed to elucidate the prognostic factors and clarify the indication of treatment for RFA outcomes in patients with HCC with a diameter > 3.0 cm. Among 2188 patients with HCC who underwent RFA, 100 patients with HCC with a diameter > 3.0 cm were enrolled in this study between August, 2000 and August, 2021. We analyzed local therapeutic efficacy, long-term outcomes, and prognostic factors in patients with HCC with a diameter > 3.0 cm. Among all patients, 77 patients achieved complete ablation in one session. There were no treatment-related deaths or major complications. Local tumor recurrence occurred in 48% (n = 48) of the patients, and distant tumor recurrence occurred in 82% (n = 82) of the patients during the study period. The survival rates at 1-, 3-, 5-, 10-, and 15- years were 93.0%, 66.0%, 40.0%, 15.5%, and 10.2%, respectively. Cox proportional hazards regression analysis confirmed that distant tumor recurrence, Child-Pugh class B, and pre-ablation des-γ-carboxy prothrombin (DCP) levels ≥ 200 mAU/mL were independent unfavorable prognostic factors with a hazard ratio of 3.34 (95% CI, 1.57-7.11; P = 0.002), 2.43 (95% CI, 1.35-4.37; P = 0.003), and 1.83 (95% CI, 1.14-2.93; P = 0.012), respectively. In conclusion, patients with HCC with a diameter > 3.0 cm with Child-Pugh class A and DCP levels < 200 mAU/mL might be eligible for RFA treatment.

Anatomical ablation for small hepatocellular carcinomas using multiple applicators: a preliminary study

BACKGROUND

Anatomical ablation, defined as thermal ablation of tumor-bearing small portal territories, may provide excellent local tumor control in peripherally-located small hepatocellular carcinomas (HCC), which has been a major concern with percutaneous ablation alone.

PURPOSE

To evaluate the technical feasibility and therapeutic outcomes of anatomical ablation using multiple radiofrequency (RF) applicators for the ablation of tumor-bearing small portal territories of peripherally-located small (≤ 4 cm) HCCs.

MATERIALS AND METHODS

Patients with peripherally-located single HCCs (≤ 4 cm) to be treated with anatomical ablation using multiple RF applicators between January 2020 and March 2022 were enrolled in this prospective study. Anatomical ablation was performed for the index tumor under real-time US-CT/MR fusion imaging guidance, with one or two clustered electrode needles placed across the tumor-bearing portal vein branches. Technical success and complications of anatomical ablations were assessed. Cumulative incidence of local tumor progression (LTP) and recurrence-free survival were estimated using the Kaplan-Meier method.

RESULTS

Fifty-five HCCs (mean size, 1.77 ± 0.59 cm) in 55 participants (mean age, 66.4 ± 7.7 years; 39 men, 16 women) were treated with anatomical ablation; 98.2% (54/55) technical success was achieved. No major complications were noted. Among the 55 participants, LTP occurred in only one patient who had experienced technical failure of anatomical ablation. Estimated 1- and 2-year cumulative incidences of LTP were 0% and 3.7%, respectively. Five patients developed intrahepatic remote recurrence during the median follow-up period of 19.2 months (range, 3.7-28.8 months); therefore, estimated 1- and 2-year recurrence-free survival was 91.7% and 85.0%, respectively.

CONCLUSION

Anatomical ablation using multiple RF applicators provided the excellent results of local tumor control in patients with peripherally-located small (≤ 4 cm) HCCs.

TRIAL REGISTRATION

clinicaltrial.gov identifier: NCT05397860.

No-Touch Radiofrequency Ablation for Early Hepatocellular Carcinoma: 2023 Korean Society of Image-Guided Tumor Ablation Guidelines

Radiofrequency ablation (RFA) has been widely used to manage hepatocellular carcinomas (HCCs) equal to or smaller than 3 cm. No-touch RFA has gained attention and has recently been implemented in local ablation therapy for HCCs, despite its technical complexity, as it provides improved local tumor control compared to conventional tumor-puncturing RFA. This article presents the practice guidelines for performing no-touch RFA for HCCs, which have been endorsed by the Korean Society of Image-Guided Tumor Ablation (KSITA). The guidelines are primarily designed to assist interventional oncologists and address the limitations of conventional tumor-puncturing RFA with describing the fundamental principles, various energy delivery methods, and clinical outcomes of no-touch RFA. The clinical outcomes include technical feasibility, local tumor progression rates, survival outcomes, and potential complications.

Treatment Outcomes of Percutaneous Radiofrequency Ablation for Hepatocellular Carcinomas: Effects of the Electrode Type and Placement Method

OBJECTIVE

To investigate the association among the electrode placement method, electrode type, and local tumor progression (LTP) following percutaneous radiofrequency ablation (RFA) for small hepatocellular carcinomas (HCCs) and to assess the risk factors for LTP.

MATERIALS AND METHODS

In this retrospective study, we enrolled 211 patients, including 150 males and 61 females, who had undergone ultrasound-guided RFA for a single HCC < 3 cm. Patients were divided into four combination groups of the electrode type and placement method: 1) tumor-puncturing with an internally cooled tip (ICT), 2) tumor-puncturing with an internally cooled wet tip (ICWT), 3) no-touch with ICT, and 4) no-touch with ICWT. Univariable and multivariable Cox proportional-hazards regression analyses were performed to evaluate the risk factors for LTP. The major RFA-related complications were assessed.

RESULTS

Overall, 83, 34, 80, and 14 patients were included in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively. The cumulative LTP rates differed significantly among the four groups. Compared to tumor puncturing with ICT, tumor puncturing with ICWT was associated with a lower LTP risk (adjusted hazard ratio [aHR] = 0.11, 95% confidence interval [CI] = 0-0.88, P = 0.034). However, the cumulative LTP rate did not differ significantly between tumor-puncturing with ICT and no-touch RFA with ICT (aHR = 0.34, 95% CI = 0.03-1.62, P = 0.188) or ICWT (aHR = 0.28, 95% CI = 0-2.28, P = 0.294). An insufficient ablative margin was a risk factor for LTP (aHR = 6.13, 95% CI = 1.41-22.49, P = 0.019). The major complication rates were 1.2%, 0%, 2.5%, and 21.4% in the ICT, ICWT, no-touch with ICT, and no-touch with ICWT groups, respectively.

CONCLUSION

ICWT was associated with a lower LTP rate compared to ICT when performing tumor-puncturing RFA. An insufficient ablation margin was a risk factor for LTP.

Evaluation of the safety and efficacy of ultrasound-guided percutaneous radiofrequency ablation for hepatocellular carcinoma and liver metastases adjacent to the gallbladder

OBJECTIVE

To evaluate the safety and efficacy of ultrasound-guided percutaneous radiofrequency ablation (RFA) in patients with hepatocellular carcinoma (HCC) and liver metastases adjacent to the gallbladder (GB).

MATERIALS AND METHODS

A total of 113 patients with 118 liver lesions (63 HCC lesions and 55 liver metastases) adjacent to the gallbladder underwent RFA between March 2011 and June 2019. Gallbladder-related complications and technique effectiveness rates were evaluated based on the classification of liver tumors and the distance between the lesion and the gallbladder.

RESULTS

Gallbladder-related complications were observed in 13 patients. Among the patients with HCC, there was no significant difference between the ≤0.5 cm and >0.5 cm groups (p = .282). However, among the patients with liver metastases, the incidence of gallbladder-related complications in the ≤0.5 cm group was significantly higher than that in the >0.5 cm group (p = .025). The overall incidence of complications was significantly higher in the ≤0.5 cm group than in the >0.5 cm group (p = .020). Among the patients with lesions ≤3 cm, the technical effectiveness rate in the HCC group was significantly higher than in the liver metastasis group (p = .036).

CONCLUSION

RFA is a safe and effective treatment option for liver tumors adjacent to the gallbladder. Patients with lesions ≤0.5 cm from the gallbladder had higher gallbladder-related complications, especially patients with liver metastases. Among patients with lesions ≤3 cm, RFA showed greater technical effectiveness for treating HCC than for treating liver metastases.

Efficacy and safety of no-touch radiofrequency ablation for small hepatocellular carcinoma-a systematic review and single-arm meta-analysis

OBJECTIVE

The purpose of this study was to report the efficacy and safety of no-touch radiofrequency ablation (NT-RFA) in the treatment of small hepatocellular carcinoma (HCC).

METHODS

We systematically searched for eligible studies in PubMed, Embase and Cochrane library until June 1, 2022. Random effect model was applied to synthesize the pooled proportions of local tumor progression-free survival (LTP), recurrence-free survival (RFS) and overall survival (OS) respectively, as well as adverse events, for small HCC treated by NT-RFA.

RESULTS

Of the 10 included studies, 3 of them reported local tumor recurrence. One reported local tumor recurrence at 19 months (range, 12-24), and 2 studies had no tumor recurrence with 24-months of follow-up. The 1- and 2-year LTP pooled proportions were 99.3% (95%CI, 97.5-100) and 97.8% (95%CI, 94.6-99.6) respectively, and two studies reported a 3-year LTP rate of 96.4% (204/212, 36/37). The 1-yearRFS rates was 91.3% (95%CI, 84.1-98.4), 2-year was 86.4% (95%CI, 75.3-97.5). The 1-, 2- and 3- year OS rates were 92.4% (95%CI, 82.8-92.7), 84.1% (95%CI, 74.7-93.6) and 81.8% (116/181, 33/36) respectively, and only one study reported a 5-year OS rate of 47.0% (85/181). The ablative success rate of the HCC nodules was 96.6% (95%CI, 91.3-99.5) and the proportions of mild and severe adverse events following ablation were 18.3% (95%CI, 8.1-41.6) and 5.0%, respectively.

CONCLUSION

NT-RFA provides safely very high rate of sustained local control for the treatment of HCC up to 5 cm.

Long‐term efficacy of no‐touch radiofrequency ablation in the treatment of single small hepatocellular carcinoma: A single center long‐term follow‐up study

OBJECTIVE

To evaluate the long-term efficacy of no-touch radiofrequency ablation (NT-RFA) for treating single hepatocellular carcinoma (HCC) less than 3 cm.

METHODS

A total of 331 patients with HCC less than 3 cm undergoing RFA in Southwest Hospital from 2015 to 2020 were analyzed retrospectively. All patients were divided into NT-RFA group (n = 113) and conventional RFA (C-RFA) group (n = 218). The survival rate, local tumor progression (LTP) and intrahepatic distant recurrence (IDR) of the two groups were calculated and compared.

RESULTS

A significant difference was observed in ablation range (p = 0.000) and safety margin (p = 0.000) between the two groups. The 1-, 2-, 3-, 4-and 5-year overall survival (OS) rates in NT-RFA and C-RFA group were 99.12%, 93.73%, 76.18%, 57.00%, 45.17% and 99.08%, 89.91%, 71.26%, 54.28%, 41.77%, respectively. There was no significant difference between the two groups (p = 0.281). The 1-, 2-, 3-, 4-and 5-year recurrence-free survival (RFS) rates in NT-RFA and C-RFA group were 78.51%, 52.59%, 41.02%, 34.36%, 30.92% and 68.81%, 44.95%, 30.88%, 23.73%, 22.88%, respectively. The two groups differed significantly (p = 0.044). The 1-, 3-and 5-year LTP-free survival rates in NT-RFA and C-RFA group were 87.12%, 74.99%, 72.32% and 75.75%, 65.52%, 65.52%, respectively. The two groups also differed significantly (p = 0.024). Furthermore, the RFS rates of D ≤ 2 cm subgroups in NT-RFA and C-RFA groups differed significantly (p = 0.037), while the RFS rates of 2 cm < D ≤ 3 cm subgroups in two groups showed no significant difference (p = 0.578).

CONCLUSIONS

The RFS rates of single HCC less than 3 cm treated by NT-RFA was significantly higher than that of C-RFA. Due to a larger ablation range and safety margin, NT-RFA could significantly reduce LTP and improve RFS. Dual-electrode NT-RFA can significantly improve the RFS rate of patients with HCC less than 2 cm, but there is no obvious advantage compared with C-RFA in the treatment of HCC over 2 cm.

Multipolar radiofrequency ablation via three bipolar electrodes with C-arm type X-ray fluoroscopy assistance for hepatocellular carcinoma: An observational study

The present study aimed to investigate the therapeutic efficacy and safety of the insertion technique of 3 bipolar electrodes in patients with hepatocellular carcinoma (HCC), using C-arm type X-ray fluoroscopy-assisted ultrasonography (US) in guiding a multipolar radiofrequency ablation (RFA) system. Seventy-three patients with HCC treated with a multipolar RFA system (1 electrode, n = 2; 2 electrodes, n = 56; 3 electrodes, n = 17) were enrolled in this retrospective cohort study. To analyze their therapeutic outcome in this study, we divided among 17 patients using 3 electrodes into 2 subgroups: the C-arm type X-ray fluoroscopy-assisted (n = 7) and the US-guided alone groups (n = 10). Therapeutic efficacy and safety were analyzed between the 2 groups. Multipolar RFA treatment was performed safely in all cases, and no severe adverse events occurred. Comparing the patient background of the group treated using 1 or 2 electrodes with that treated using 3 electrodes, larger-sized HCC was treated using 3 electrodes (P < .001). The differences in overall and recurrence-free survival rates between the 1- or 2-electrode and the 3-electrode groups were not significantly different (P = .843 and P = .891). Comparing the C-arm type X-ray fluoroscopy-assisted and the US-guided alone groups among patients treated using 3 electrodes, technical factors such as total ablation time and the number of sessions were not significantly different between the 2 groups. The local tumor progression rate was not significantly different between the 2 groups (P = .942). Multipolar RFA treatment was effective for the treating HCC; using 3 electrodes was suitable for larger-sized HCCs. The technical approach with C-arm type X-ray fluoroscopy assistance using 3 electrodes was useful for operators to perform safe and appropriate insertion techniques by synchronizing the US and X-ray fluoroscopy images.

Can "no-touch" radiofrequency ablation for hepatocellular carcinoma improve local tumor control? Systematic review and meta-analysis

OBJECTIVES

Percutaneous radiofrequency ablation (RFA) is one of the curative treatments for hepatocellular carcinoma (HCC), but local tumor progression (LTP) has been a main limitation of RFA. This study aims to evaluate the LTP of percutaneous no-touch RFA (NtRFA) for HCC ≤ 5 cm and compare with conventional RFA (intratumoral puncture) through a systematic review and meta-analysis.

METHODS

MEDLINE, EMBASE, and Cochrane Library were searched for studies on percutaneous NtRFA for HCC ≤ 5 cm. The pooled proportions of the overall and cumulative incidence rates at 1, 2, and 3 years for LTP after NtRFA were assessed using a random-effects model. For studies comparing NtRFA with conventional RFA, relative risks (RR) and hazard ratios (HR) were meta-analytically pooled with LTP as the outcome.

RESULTS

Twelve studies with 900 patients were included. The pooled overall rate of LTP after NtRFA was 6% (95% CI, 4-8%). The pooled 1-, 2-, and 3-year cumulative incidence rates of LTP were 3% (95% CI, 2-5%), 5% (95% CI, 3- 9%), and 8% (95% CI, 6-11%), respectively. Compared to conventional RFA, the pooled RR and HR of LTP were 0.26 (95% CI, 0.16-0.41) and 0.28 (95% CI, 0.11-0.70), respectively (both p < 0.01). Subgroup analysis including only randomized controlled studies also showed better local tumor control of NtRFA with HR of 0.13 (95% CI, 0.14-0.42).

CONCLUSIONS

Percutaneous NtRFA is an effective treatment for HCC ≤ 5 cm with an overall LTP rate of 6% and provides lower LTP compared with conventional RFA.

KEY POINTS

• The pooled 1-, 2-, and 3-year cumulative incidence rates of local tumor progression after no-touch radiofrequency ablation for HCC ≤ 5 cm were 3% (95% CI, 2-5%), 5% (95% CI, 3-9%), and 8% (95% CI, 6-11%). • No-touch radiofrequency ablation had significantly lower rates of local tumor progression compared to conventional radiofrequency ablation (hazard ratio, 0.28; 95% CI, 0.11-0.70; relative risk, 0.26; 95% CI, 0.16-0.41; p < 0.01, respectively).

Impact of Extended Use of Ablation Techniques in Cirrhotic Patients with Hepatocellular Carcinoma: A Cost-Effectiveness Analysis

Simple Summary

The optimal management of non-metastatic hepatocellular carcinoma (HCC) remains debated. The association between HCC and cirrhosis influences prognosis and therapeutic choices between curative and palliative treatments. The goal of our retrospective study was to evaluate the cost-effectiveness of the extended use of ablation for the treatment of HCC with cirrhosis in an expert ablation center when compared to the non-extended use of ablation in equivalent tertiary care centers. In a propensity-score matched cohort of 532 patients with naïve HCC, the extended use of ablation led to better compliance with the Barcelona Clinic Liver Classification (BCLC) guidelines (80% vs. 67%) and was more effective and less expensive than the non-extended use of ablation strategy, particularly at an earlier stage of the disease. The shift from curative to palliative treatments was noted in a considerable percentage of patients; therefore, this needs to be redefined as the wide choice of ablation techniques and technical advances in imaging guidance increase the curative options available to treat a maximum of patients with HCC.

Abstract

Background: To evaluate the cost-effectiveness of the extended use of ablation for the treatment of hepatocellular carcinoma (HCC) with cirrhosis in an expert ablation center when compared to the non-extended use of ablation in equivalent tertiary care centers. Methods: Consecutive cirrhotic patients with non-metastatic HCC, no prior treatment, and referred to three tertiary care centers between 2012 and 2016 were retrospectively identified. The Bondy group, including all of the patients treated at Jean Verdier Hospital, where the extended use of ablation is routinely performed, was compared to the standard of care (SOC) group, including all of the patients treated at the Beaujon and Mondor Hospitals, using propensity score matching. A cost-effectiveness analysis was carried out from the perspective of French health insurance using a Markov model on a lifetime horizon. Results: 532 patients were matched. The Bondy group led to incremental discounted lifetime effects of 0.8 life-years gained (LYG) (95% confidence interval: 0.4, 1.3) and a decrease in lifetime costs of EUR 7288 (USD 8016) (95% confidence interval: EUR 5730 [USD 6303], EUR 10,620 [USD 11,682]) per patient, compared with the SOC group, resulting in a dominant mean incremental cost-effectiveness ratio (ICER). A compliance with the Barcelona Clinic Liver Classification (BCLC) guidelines for earlier stage contributed to the greater part of the ICER. Conclusion: The extended use of ablation in cirrhotic patients with HCC was more effective and less expensive than the non-extended use of the ablation strategy.

Outcome of No-Touch Radiofrequency Ablation for Small Hepatocellular Carcinoma: A Multicenter Clinical Trial

Background Recently introduced no-touch radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) has the potential to improve local tumor control. Purpose To evaluate midterm clinical outcomes of monopolar no-touch RFA in single HCCs 2.5 cm or smaller. Materials and Methods In this multicenter clinical trial (ClinicalTrials.gov: NCT03375281), participants were evaluated for eligibility from November 2017 to January 2019. Patients with single HCCs 2.5 cm or smaller planning to be treated with no-touch RFA were enrolled. The rate of successful no-touch RFA, defined as performing RFA without violation of the tumor itself, was recorded. Multivariable logistic regression analysis was used to determine associated factors for failure of no-touch RFA. Development of major complication after no-touch RFA was also recorded. Cumulative incidence of local tumor progression (LTP) and recurrence-free survival were estimated by using the Kaplan-Meier method. Results A total of 140 participants (mean age, 62 years ± 9 [standard deviation]; 106 men) were evaluated. No-touch RFA was successfully performed in 128 participants (128 of 140; 91.4%), and conversion to tumor puncture RFA was undertaken in 12 participants because of the lack of a safe access route. By using either no-touch RFA or conversion to tumor puncture RFA, all participants achieved technical success of RFA, which was defined as complete coverage of target tumor by ablation zone. Insufficient peritumoral parenchyma (<5 mm width around more than half portion of tumor; odds ratio, 74; 95% CI: 18, 309; P < .001) was the only significant predictive factor for failure of the no-touch technique. Among the 140 participants, LTP developed in two participants, and the estimated 1- and 2-year cumulative incidence of LTP was 0.7% and 1.6%, respectively. The estimated 1- and 2-year recurrence-free survival was 82.8% and 74.1%, respectively. Conclusion No-touch radiofrequency ablation was an effective and safe treatment method for small hepatocellular carcinomas (≤2.5 cm), with 1.6% of cumulative incidence of local tumor progression at 2 years. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Soulen and García-Mónaco in this issue.

No-Touch Radio Frequency Ablation for a Subcapsular Hepatocellular Carcinoma: A Case Report and Review of Literature

Radiofrequency Ablation of subcapsular lesions poses a challenge due to the risks of tumour seeding along the track, hemorrhage and lower efficacy. “No touch ablation” is a relatively novel technique used in the ablation of subcapsular HCC with good results. This technique avoids direct puncture of the tumour by inserting more than one electrodes adjacent to and outside the tumor and activating them sequentially to perform ablation. The risk of track site seeding and haemorrhage is significantly reduced. We describe a case of a subcapsular HCC in a 65-year-old female patient which was successfully treated with this novel technique.

Perivascular vital cells in the ablation center after multibipolar radiofrequency ablation in an in vivo porcine model

Multibipolar radiofrequency ablation (RFA) is an advanced ablation technique for early stage hepatocellular carcinoma and liver metastases. Vessel cooling in multibipolar RFA has not been systematically investigated. The objective of this study was to evaluate the presence of perivascular vital cells within the ablation zone after multibipolar RFA. Multibipolar RFA were performed in domestic pigs in vivo. Three internally cooled bipolar RFA applicators were used simultaneously. Three experimental settings were planned: (1) inter-applicator-distance: 15 mm; (2) inter-applicator-distance: 20 mm; (3) inter-applicator-distance: 20 mm with hepatic inflow occlusion (Pringle maneuver). A vitality staining was used to analyze liver cell vitality around all vessels in the ablation center with a diameter > 0.5 mm histologically. 771 vessels were identified. No vital tissue was seen around 423 out of 429 vessels (98.6%) situated within the central white zone. Vital cells could be observed around major hepatic vessels situated adjacent to the ablation center. Vessel diameter (> 3.0 mm; p < 0.05) and low vessel-to-ablation-center distance (< 0.2 mm; p < 0.05) were identified as risk factors for incomplete ablation adjacent to hepatic vessels. The vast majority of vessels, which were localized in the clinically relevant white zone, showed no vital perivascular cells, regardless of vessel diameter and vessel type. However, there was a risk of incomplete ablation around major hepatic vessels situated directly within the ablation center. A Pringle maneuver could avoid incomplete ablations.

The Learning Curve for Thermal Ablation of Liver Cancers: 4,363-Session Experience for a Single Central in 18 Years

This study aimed to explore the special efforts required to achieve proficiency in performing thermal ablation of liver cancers, including tumors in difficult locations, and clarify the effects of handing-down teaching on the corresponding process. Major complications of patients receiving percutaneous thermal ablation of liver cancer were analyzed. Polynomial fitting was used to describe the connection between major complication rates and special experience. Learning curve of major complications was plotted both for the whole group and for each operator, respectively. Tumors in difficult locations were further studied. A total of 4,363 thermal ablation sessions were included in this study. 143 of 4,363 patients had major complications, corresponding to an incidence rate of 3.27%. 806 thermal ablation sessions were performed for tumors in difficult locations. The major complication rate of these sessions is 6.33%. According to the trend of the learning curve of the 4363 patients, the experience of the whole group can be classified into five stages, that is, the high-risk, relatively stable, unstable, proficient and stable periods. A learning curve for an individual operator can be classified into the high-risk, proficient and stable periods. The major complication rates for the chronologically first, second and third operator of the group are 3.23, 3.35, and 3.31%, respectively. The special experience needed to bypass the first stage corresponds to 410, 510, and 440 sessions, the second stage, 1850, 850, and 870 sessions, by the three operators, respectively. The major complication rates for the tumors in difficult locations for the first, second and third operator were 7.04, 5.53, and 5.98%, respectively. For the tumors in difficult locations, the special experience needed to bypass the first stage corresponds to 150, 130, and 140 sessions, the second stage, 290, 175, and 185 sessions, by the three operators, respectively. In conclusion, the learning process of an operator percutaneous thermal ablation for liver cancer can be classified into three stages. The major complication rate for tumors in difficult locations were higher than that for all tumors. Handing-down teaching can make an operator arrive at the third stage earlier but not the second stage.

Influence of interapplicator distance on multibipolar radiofrequency ablation during physiological and interrupted liver perfusion in an in vivo porcine model

Radiofrequency ablation (RFA) is a curative treatment option for early stage hepatocellular carcinoma (HCC). Vascular inflow occlusion to the liver (Pringle manoeuvre) and multibipolar RFA (mbRFA) represent possibilities to generate large ablations. This study evaluated the impact of different interapplicator distances and a Pringle manoeuvre on ablation area and geometry of mbRFA. 24 mbRFA were planned in porcine livers in vivo. Test series with continuous blood flow had an interapplicator distance of 20 mm and 15 mm, respectively. For a Pringle manoeuvre, interapplicator distance was predefined at 20 mm. After liver dissection, ablation area and geometry were analysed macroscopically and histologically. Confluent and homogenous ablations could be achieved with a Pringle manoeuvre and an interapplicator distance of 15 mm with sustained hepatic blood flow. Ablation geometry was inhomogeneous with an applicator distance of 20 mm with physiological liver perfusion. A Pringle manoeuvre led to a fourfold increase in ablation area in comparison to sustained hepatic blood flow (p < 0.001). Interapplicator distance affects ablation geometry of mbRFA. Strict adherence to the planned applicator distance is advisable under continuous blood flow. The application of a Pringle manoeuvre should be considered when compliance with the interapplicator distance cannot be guaranteed.

Computed Tomography-Guided Percutaneous Cryoablation for ‎ Subcardiac Hepatocellular Carcinoma: Safety, Efficacy, Therapeutic Results and Risk Factors for Survival Outcomes

Objective

To investigate the clinical safety, efficacy, therapeutic outcomes and risk factors of computed tomography-guided percutaneous cryoablation (CT-PCRA) for subcardiac hepatocellular carcinoma (HCC).

Patients and Methods

In this study, patients with single HCC nodules located on the left lobe who subsequently underwent CT-PCRA were reviewed from July 2012 to August 2016. According to the definition of subcardiac HCC, the patients were grouped into the subcardiac HCC group (n=33) and the non-subcardiac HCC group (n=40). The technical success rates, tumour response rates, oncological outcomes including overall survival (OS) and recurrence-free survival (RFS) and complications were compared. Multivariate analysis was performed on clinicopathological variables to identify factors affecting long-term outcomes.

Results

Seventy-three patients with subcardiac HCC were included in this study. After a median follow-up time of 37.8 months, 27.4% (20/73) of the patients died. The technical success and complete response rates were not significantly different between the two groups (p = 1.000; p = 0.590). The cumulative OS and RFS of the subcardiac HCC group were comparable to those of the non-subcardiac HCC group (p =0.820, p =0.922). Two major complications, intra-abdominal bleeding and right pleural effusion, were found at 2.2 and 3.1 months in the subcardiac HCC group, which were comparable with those in the non-subcardiac HCC group (p = 0.683). The multivariate analysis results showed that older age (hazard ratio [HR]: 2.382, 95% confidence interval [CI]: 1.884–7.823; p = 0.038) and ALBI grade 2–3 (HR: 3.398, 95% CI: 1.950–6.058; p = 0.021) may be predictors of poor OS and that tumour size ≥3 cm in diameter (HR: 3.302, 95% CI: 2.232–8.293; p = 0.012) may be a predictor of poor RFS.

Conclusion

CT-PCRA for subcardiac HCC can be performed safely and efficiently and contribute to improving survival prognosis.