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Optimal multibipolar parameters should overcome heat-sink effect

We read with great interest the well-written and very informative article of Franz G. M. Poch and co-worker assessing the vascular cooling effect in hepatic multibipolar radiofrequency ablation (RFA) [1] and concluded that multibipolar RFA is significantly impacted by heat-sink effect. As recalled by the authors, heat-sink effect is a major cause of local tumour progression and multibipolar RFA has been developed to overcome this problem by delivering higher energy than monopolar RFA. In our recent study, we found that multibipolar RFA provides improved sustained tumour control compared with monopolar RFA for hepatocellular carcinoma near vessels >3mm diameter [2]. The local progression rates for multipolar vs. monopolar RFA were 12.5 and 40%, respectively. We wish to discuss several points on the RFA procedure that could explain the discordance between our clinical results vs. the ex vivo results of Poch et al.: