A cooled needle electrode for radiofrequency tissue ablation: Thermodynamic aspects of improved performance compared with conventional needle design

Rationale and Objectives. I developed and tested a cooled needle electrode (CNE) for radiofrequency (RF) tissue ablation in vitro. Methods. A 2-mm needle electrode with two lumina for internal water perfusion and irrigation of the needle tip and a conventional needle electrode were tested in ex vivo calf liver during different levels of output power (wattage). RF lesions produced by the two needle types were further evaluated with a thermal camera. Results. When the CNE was used, a significant increase in the duration of ablation was observed, which caused a significant increase in delivered energy and lesion size when compared with the conventional needle electrode. The largest lesion produced with the CNE was almost spherical and measured 41 x 37 mm (longitudinal x transverse). The cooling effect was reflected in the image obtained with the thermal camera. Conclusion. This technique produced very large lesions compared with conventional methods and may have a role in many different kinds of RF needle ablation.