2015 Volume 33 Issue 1 Pages 1-6
An increase in tissue temperature or impedance (IMP) has each been used as endpoints for an ablation with monopolar radiofrequency induced thermotherapy (RFITT) system. In contrast, endpoint for an ablation using bipolar RFITT system is given by the total delivered energy that is determined depending on the types and number of applied needles (applicators). However, treatment endpoint defined by the delivered energy alone is associated with an increased risk for insufficient ablation. This experimental study verified optimal endpoint for bipolar ablation using ex-vivo porcine liver. We found that actual power output (“Power Effect” (PE)) and IMP were electrotechnically essential as indices for sufficient coagulation. In all experiments, sufficient coagulation was obtained when the procedure was finished after PE was below 5W and IMP between each electrode become higher than that of baseline. Using this endpoints, sufficient coagulation was achieved even when applicators were inserted with distance of 50 mm, which was longer than the recommended distance by dosimetry table. In addition, with applicators distance of 13 mm or less, shorter ablation time and smaller delivered energy than their recommended values were available to obtain sufficient coagulation.