Stephan Clasen MD, Presenter: Nothing to Disclose

Diethard Schmidt MD, Abstract Co-Author: Nothing to Disclose

Christina Schraml, Abstract Co-Author: Nothing to Disclose

Andreas Boss MD, Abstract Co-Author: Nothing to Disclose

Claus Detlef Claussen MD, Abstract Co-Author: Nothing to Disclose

Philippe Lucien Pereira MD, Abstract Co-Author: Nothing to Disclose

To evaluate the relationship between applied energy and volume of coagulation induced by multipolar radiofrequency (RF) ablation using an array of internally cooled bipolar applicators.

Multipolar RF ablations (n = 80) were performed in ex-vivo bovine liver. Three bipolar applicators with two electrodes located on each applicator shaft were placed in a triangular array. The application of RF energy was switched between 15 possible pairs of electrodes. The power-output (75 – 225 Watts) and the distance between the different applicators (2, 3, 4, 5 cm) were systematically varied. The volume of confluent white coagulation and the amount of applied energy were assessed. Based on our experimental data the relationship between the volume of coagulation and applied energy was assessed by nonlinear regression analysis. The variability explained by the model was determined by the parameter r².

The parameters volume of coagulation and amount of applied energy in relation to the power-output and applicator distance were: 2cm: 101cm³, 155kJ (75W) - 40cm³, 22kJ (225W); 3cm: 156cm³, 201kJ (75W) - 50cm³, 32kJ (225W); 4cm: 211cm³, 260kJ (75W) - 101cm³, 72kJ (125W); 5cm: 324cm³, 453kJ (75 W) - 157cm³, 129kJ (100W), respectively. The relationship between amount of applied energy (E) and volume (V) of coagulation can be described by mathematical modeling, V = 4.4E0.7 (r² = 0.88). By approximation the volume of coagulation can be calculated by the linear function V = 0.6E + 40.7 (r² = 0.87).

Ex-vivo the volume of coagulation induced by multipolar RF ablation can be predicted from the amount of applied energy.

The amount of applied energy may be useful to control multipolar RF ablation.

Clasen, S, Schmidt, D, Schraml, C, Boss, A, Claussen, C, Pereira, P, Multipolar Radiofrequency Ablation Using Internally Cooled Electrodes in ex Vivo Bovine Liver: Prediction of Coagulation Volume from Applied Energy.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5006969.html