Although RFA is widely used as a curative treatment option for a variety of liver malignancies, it is generally limited for treating tumors larger than 2 cm in diameter with a sufficient tumor-free margin. Thus, various strategies are employed to create a sufficient ablation zone such as internally cooled-electrodes, expandable electrodes and adaptation of switching mono/bipolar controllers. Despite that these attempts have created larger ablative zones in clinical and preclinical studies, the efficacy should be validated in terms of clinical outcome.