Multiple probe hepatic radio-frequency ablation: ex-vivo experiments in the porcine model

Radio-frequency (RF) ablation is an important means of treatment of non-resectable primary and metastatic liver tumors. The RF ablation of any but the smallest tumor requires the use of multiple overlapping treatment zones. Commercially available RF ablation generators, unlike cryoablation (a method of tumor destruction that utilizes cold rather than heat), are only capable of driving a single RF probe at a time. Using multiple probes simultaneously in RF ablation is desirable for treating large tumors and for treating multiple tumor metastases. Bipolar RF ablation, which has been previously studied by other groups, allows simultaneous usage of two probes. The energy converted to heat at each probe for bipolar RF ablation is necessarily equal. There have been no investigations of other methods that allow usage of multiple RF probes simultaneously. We investigated the feasibility of a new method, where power is applied in an alternating fashion between two or more probes. This method allows independent control of the amount of energy deposited at each probe. We performed ex-vivo experiments with one (i.e. conventional ablation) and with two probes. In the two-probe experiment, both probes reached target temperature and created lesions of sizes comparable to conventional RF ablation.