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Background/Aim: Lenvatinib is available as a molecular target agent for hepatocellular carcinoma (HCC). In this study, we investigated the popping phenomena in patients with HCC who underwent radiofrequency ablation (RFA) after taking lenvatinib. Patients and Methods: Fiftynine patients with HCC between 21-30 mm in diameter and no history of systemic treatment were enrolled in the study. The patients underwent RFA using a VIVA RFA SYSTEM with an ablation tip of 30 mm in length. For the initial lenvatinib administration, 16 patients had an adequate course of treatment and were treated with RFA as add-on therapy (combination group). The other 43 patients were treated by RFA monotherapy (monotherapy group). The popping frequency during RFA was recorded and compared. Results: Popping frequency in the combination group (RFA combined with lenvatinib) was significantly higher than that in the monotherapy group. There was no significant difference between the combination group and the monotherapy group in ablation time, maximum output level, tumour temperature after ablation, or initial resistance value. Conclusion: Popping frequency was significantly higher in the combination group. It is possible that the intra-tumour temperature increased rapidly during RFA in the combination group due to the inhibitory effect of lenvatinib on tumour angiogenesis, leading to the occurrence of popping. Further studies are needed to investigate popping after RFA, and precise protocols need to be developed.

Background Microwave ablation (MWA) is a standard percutaneous local therapy for hepatocellular carcinoma (HCC). Next-generation MWA is reported to create a more spherical ablation zone than radiofrequency ablation (RFA). We compared the ablation zone and aspect ratio of two 2.45 GHz MWA ablation probes; Emprint ® (13G) and Mimapro ® (17G). We compared the ablation zone to the applied energy after MWA in patients with hepatocellular carcinoma (HCC). Furthermore, we investigated local recurrence. Materials and Methods We included 20 patients with HCC, with an average tumour diameter of 33.2 ± 12.2 mm, who underwent MWA using Emprint ® , and 9 patients who underwent MWA using Mimapro ® with an average tumour diameter of 31.1 ± 10.5 mm. Both groups underwent the same ablation protocol using the same power settings. The images obtained after MWA showed the treatment ablation zone and aspect ratio, which were measured and compared using three-dimensional image analysis software. Results The aspect ratios in the Emprint ® and Mimapro ® groups were 0.786 ± 0.105 and 0.808 ± 0.122, respectively, with no significant difference (p = 0.604). The ablation time was significantly shorter in the Mimapro ® group than in the Emprint ® group, and there was no significant difference in the frequency of popping or the ablation volume. There were no significant differences in local recurrence between the two groups. Conclusion There was no significant difference in the aspect ratios of the ablation diameter, and the ablation zone was almost spherical in both cases. Mimapro ® at 17G was less invasive than Emprint ® at 13G.