Radiofrequency ablation zones in ex vivo bovine and in vivo porcine livers: comparison of the use of internally cooled electrodes and internally cooled wet electrodes.

This experimental study was undertaken to compare radiofrequency (RF) ablation zones created by internally cooled (IC) and internally cooled wet (ICW) electrodes. IC and ICW electrodes with a 2-cm exposed active tip were used to induce 30 ablation zones in 10 explanted bovine livers with a 12-min ablation time, respectively. In addition, two kinds of electrodes produced 16 ablation zones in five living porcine livers, respectively. In explanted bovine livers using IC and ICW electrodes, the mean long-axis diameter, short-axis diameter, volume, and variable coefficient of long-axis diameters of the ablation zones were 3.01 cm, 2.62 cm, 11.08 cm3, 10%, 5.28 cm, 5.07 cm, 73.48 cm3, and 14%, respectively. In living porcine livers using IC and ICW electrodes, the corresponding values were 2.62 cm, 2.00 cm, 5.76 cm3, 15%, 3.84 cm, 2.89 cm, 18.50 cm3, and 25%, respectively. In both ex vivo and in vivo livers, long-axis diameters, short-axis diameters, volumes, and variable coefficients for the use of ICW electrodes were significantly greater than for the use of IC electrodes (each p<0.05). ICW electrodes produced significantly larger ablation zones than IC electrodes in both ex vivo and in vivo livers, but the ablation zones induced by IC electrodes were more reproducible.