Clinical evaluation of a novel bipolar radiofrequency ablation system for renal masses

OBJECTIVE To evaluate a novel bipolar radiofrequency ablation (BRFA) system for the destruction of kidney tumours in patients. MATERIALS AND METHODS Bipolar radiofrequency ablation (BRFA) was used to ablate renal masses in 10 patients undergoing laparoscopic radical or partial nephrectomy. The probe was placed percutaneously and laparoscopically guided into the tumour after routine laparoscopic exposure. The electrical current was continuously adjusted by the generator to overcome disruption from increasing impedance created from desiccated tissue. The specimens were then excised in routine fashion and analysed by a single pathologist. Lesion size and shape, and size of the transition zone to viable tissue were measured via nicotinamide adenine dinucleotide (NADH) staining. RESULTS Ablation was successful in all 10 tumours. Mean time to set up and place the probe was between 2 and 4 min. Duration of ablation was 200 s. None of the ablated tissue showed signs of viable cells by histological examination and NADH staining. The mean size of the ablation zone was 6.26 cm(3), with regular borders and a tapered cylindrical shape similar to the shape of the outer coil. The width of the transition zone, or area spanning complete tissue ablation to the first viable cells, ranged from 10 to 60 mu m. There were no complications noted due to the ablation. CONCLUSIONS A BRFA device can produce a defined reproducible lesion with a precise transition zone to normal tissue. The area of ablated tissue exhibited completely devitalized cells and precise transition zone.