Background Successful endovenous thermoablation relies on transmural vein wall ablation. We investigated the pattern of thermal spread and tissue carbonisation from RadioFrequency-induced ThermoTherapy (RFiTT) at different powers and pull back methods, using a porcine liver model. Methods We used a previously validated in-vitro porcine liver model. Different powers from 5–25 W were used to administer 150 J. We compared continuous and pulsed energy delivery. Length, lateral spread, and total area of thermal damage, together with any tissue carbonisation, was measured using digital analysis software. Results All experiments used 150 J total energy. Total thermal damage area was smaller with lower power and pulsed energy. Continuous energy caused more tissue carbonisation than pulsed except at 25 W. Conclusion Reduced thermal damage with lower power or pulsed energy results from cooling due to increased time of treatment. Increasing the power increases tissue carbonisation. Optimal treatment is determined by the highest power used continuously that does not cause tissue carbonisation.

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