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.