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 elect rode (CNE) for radiofrequency (RF) tissue ablation in vitro. Methods. A 2-mm needle electrode with two lumina for internal water perfusion a nd irrigation of the needle tip and a conventional needle electrode we re tested in ex vivo calf liver during different levels of output powe r (wattage). RF lesions produced by the two needle types were further evaluated with a thermal camera. Results. When the CNE was used, a sig nificant increase in the duration of ablation was observed, which caus ed a significant increase in delivered energy and lesion size when com pared with the conventional needle electrode. The largest lesion produ ced with the CNE was almost spherical and measured 41 x 37 mm (longitu dinal x transverse). The cooling effect was reflected in the image obt ained with the thermal camera. Conclusion. This technique produced ver y large lesions compared with conventional methods and may have a role in many different kinds of RF needle ablation.