RADIOFREQUENCY ABLATION OF THE LIVER IN-V ITRO - INCREASING THE EFFICACY VIA PERFUSION ELECTRODES

Purpose: Percutaneous radiofrequency interstitial thermal ablation is a new method in local tumour therapy. The aim of this study was to def ine the relations between the variable parameters and local efficacy i n vitro and to evaluate optimal parameter combinations for this system . Furthermore, we studied the feasibility of increasing the volume of destroyed tissue using perfusion electrodes. Material and methods: The rmal lesions were produced with radiofrequency in ex vivo pig livers. In separate experiments the parameters wattage (5-30 watts), exposure time (1-15 minutes) and tip exposure were varied. The resulting areas of tissue necrosis coagulation were measured; in 30 of 90 cases the ma croscopic findings were compared to the histological findings. Results : Lesion size correlated with tip exposure, wattage and procedure dura tion up to 10 minutes. For a tip exposure of 2 cm (3 cm) the maximal l esion volume was 18.8 cm(3) (33.2 cm(3)) at a wattage of 20 watts (30 watts) and a procedure duration of 10 minutes. The maximal cross- (len gth-) diameter of these lesions was 3 cm (4 cm) for 2 cm tip exposure and 3.6 cm (4.9 cm) for 3 cm tip Exposure. Conclusion: The parameters wattage, procedure duration and tip exposure affect the size of lesion s created with radiofrequency under ex vivo conditions. Perfusion elec trodes make it possible to produce larger lesions than described For n on-perfused electrodes. The ablation of hepatic neoplasms up to a size of 3 cm seems to be possible with a single electrode.