Comparison of Ablation Volume Between Emprint® and Mimapro® Systems for Hepatocellular Carcinoma -A Preliminary Study.

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.

An Investigation of Popping During Radiofrequency Ablation After Lenvatinib Administration for Hepatocellular Carcinoma.

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: Fifty-nine 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.

Ex Vivo Experimental Study of the Ablation Area of Bovine Liver Using STARmed Radiofrequency Ablation.

BACKGROUND/AIM: Ablating a spherical area during hepatocellular carcinoma ablation therapy is a very important issue. We aimed to determine the ablation area of bovine liver using various radiofrequency ablation (RFA) protocols. MATERIALS AND METHODS: Bovine liver (1-2 kg) was placed in an aluminum tray, which was punctured with STARmed VIVA 2.0 17-gauge (G) and 15-G electrodes using a current-carrying tip. Under the step-up or linear method, with an ablation time up to one break and RFA output stop, the size of the color change area (representing the thermally coagulated area) of the bovine liver was measured along the vertical and horizontal axes, and the ablated volume and total heat generated were calculated. RESULTS: 5-W per minute increases protocol resulted in greater horizontal and vertical diameters of the ablated area than 10-W per minute increases protocol under the step-up method. For 5-W and 10-W per minute increases under the step-up method, the aspect ratio was 0.81 and 0.67 with a 17-G electrode, and 0.73 and 0.69 with a 15-G electrode, respectively. For 5-W and 10-W increases under the linear method, the aspect ratio was 0.89 and 0.82, respectively. Sufficient ablation was obtained, with vertical and horizontal diameters of 50 mm and 43.50 mm, respectively. Although the ablation time was long, the watt output value at the break and average watt value were low. CONCLUSION: Gradual increase in output (5 W) using the step-up method yielded a more spherical ablation area, and longer ablation time in the linear method with a 15-G electrode could result in a more spherical ablation area in real clinical practice in humans. Future studies should examine concerns regarding long ablation times.