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


CONCLUSIONS
This technique produced very large lesions compared with conventional methods and may have a role in many different kinds of RF needle ablation.
Lorentzen
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Department of Ultrasound, Herlev Hospital, University of Copenhagen, Herlev, Denmark.
D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D002417:Cattle; D004567:Electrodes, Implanted; D004867:Equipment Design; D066298:In Vitro Techniques; D008099:Liver / Q000601:surgery; D009339:Needles; D013696:Temperature; D007507:Therapeutic Irrigation