Comparison of no-touch multi-bipolar vs. monopolar radiofrequency ablation for small HCC

Aggressive tumor recurrence after radiofrequency ablation for hepatocellular carcinoma

Image-guided radiofrequency ablation (RFA) is an evolving and growing treatment option for patients with hepatocellular carcinoma (HCC) and hepatic metastasis. RFA offers significant advantages as it is less invasive than surgery and carries a low risk of major complications. However, serious complications, including aggressive tumor recurrence, may be observed during follow-up, and recently, mechanical or thermal damage during RFA has been proposed to be one of the causes of this kind of recurrence. Although the exact mechanism of this still remains unclear, physicians should be familiar with the imaging features of aggressive tumor recurrence after RFA for HCC and its risk factors. In addition, in order to prevent or minimize this newly recognized tumor recurrence, a modified RFA technique, combined RFA treatments with transarterial chemoembolization, and cryoablation can be used as alternative treatments. Ultimately, combining an understanding of this potential complication of RFA with an understanding of the possible risk factors for aggressive tumor recurrence and choosing alternative treatments are crucial to optimize clinical outcomes in each patient with HCC.

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.

Radiofrequency ablation using a 10-mm target margin for small hepatocellular carcinoma in patients with liver cirrhosis: A prospective randomized trial

BACKGROUND AND OBJECTIVES

To compare 3-year clinical outcomes of radiofrequency ablation (RFA) targeting 5- or 10-mm margins for small hepatocellular carcinomas (HCCs) in cirrhotic patients.

METHODS

In total, 96 cirrhotic patients with a small solitary HCC (diameter ≤3 cm) were included in this prospective trial (ChiCTRTRC-10000954). Patients were stratified by Child-Pugh class and randomly allocated into groups targeting either wide margins (≥10 mm, WM) or narrow margins (≥5 mm but <10 mm, NM). RFA was performed under real-time monitoring, and ablative margins were evaluated by pre- and post-operative three-dimensional registration on CT.

RESULTS

The mean follow-up time was 38.3 ± 4.8 months, 83.3% (40/48) of patients succeeded in obtaining a 10-mm margin in WM group. Based on intention-to-treat analysis, the 3-year incidences of local tumor progression (LTP) (14.9% vs 30.2%), intrahepatic recurrence (IHR) (15.0% vs 32.7%), and recurrence-free survival (RFS) (31.7 ± 12.1 vs 24.0 ± 11.7 months) for WM group were significantly improved compared to NM group. Several prognostic factors were identified from univariate and multivariate analyses. Additionally, cirrhosis-stratified subgroup analyses demonstrated significant survival benefits of WM in patients with Child-Pugh class B cirrhosis.

CONCLUSIONS

RFA treatment targeting 10-mm margin may reduce the risk of tumor recurrence in cirrhotic patients with a single small HCC.

No-Touch Radiofrequency Ablation: A Comparison of Switching Bipolar and Switching Monopolar Ablation in Ex Vivo Bovine Liver

OBJECTIVE

To evaluate the feasibility, efficiency, and safety of no-touch switching bipolar (SB) and switching monopolar (SM) radiofrequency ablation (RFA) using ex vivo bovine livers.

MATERIALS AND METHODS

A pork loin cube was inserted as a tumor mimicker in the bovine liver block; RFA was performed using the no-touch technique in the SM (group A1; 10 minutes, n = 10, group A2; 15 minutes, n = 10) and SB (group B; 10 minutes, n = 10) modes. The groups were compared based on the creation of confluent necrosis with sufficient safety margins, the dimensions, and distance between the electrode and ablation zone margin (DEM). To evaluate safety, small bowel loops were placed above the liver surface and 30 additional ablations were performed in the same groups.

RESULTS

Confluent necroses with sufficient safety margins were created in all specimens. SM RFA created significantly larger volumes of ablation compared to SB RFA (all p < 0.001). The DEM of group B was significantly lower than those of groups A1 and A2 (all p < 0.001). Although thermal injury to the small bowel was noted in 90%, 100%, and 30% of the cases in groups A1, A2, and B, respectively, full depth injury was noted only in 60% of group A2 cases.

CONCLUSION

The no-touch RFA technique is feasible in both the SB and SM modes; however, SB RFA appears to be more advantageous compared to SM RFA in the creation of an ablation zone while avoiding the unnecessary creation of an adjacent parenchymal ablation zone or adjacent small bowel injuries.