Tissue Property Characterization and Radiofrequency Ablation Enhancement by Electroporation: An In Vivo and Computational Study

Radiofrequency ablation (RFA) is an energy-based tumor ablation modality that heats tissues by delivering radiofrequency current. The tissue properties of both electrical and thermal conductivities dominate the efficiency of RFA. This study aims to investigate the potential of electroporation (EP) pretreatment to enhance RFA by increasing the electrical and thermal conductivities of tissues. A rabbit liver model was used in an in vivo experiment to do the following: 1) characterize the change of electrical conductivity and thermal conductivity after various EP protocols and 2) explore the RFA enhancement with previous EP by comparing the ablation zone among the groups of different ablation protocols. Furthermore, a computer model, validated by the in vivo experiment, was built to study the enhancing effect of previous EP on RFA treatments. Compared with untreated tissues, the maximum electrical and thermal conductivities of liver tissues treated by EP treatments could be obtained at the electric field strengths of 2500 and 1500 V/cm, respectively, which increased by 16.54% (from <inline-formula> <tex-math notation="LaTeX">$0.29~\pm ~0.11$ </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">$0.34~\pm ~0.01$ </tex-math></inline-formula> S/m) and 65.17% [from <inline-formula> <tex-math notation="LaTeX">$0.71~\pm ~0.03$ </tex-math></inline-formula> to <inline-formula> <tex-math notation="LaTeX">$1.18~\pm ~0.12$ </tex-math></inline-formula> W/(m<inline-formula> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>K)], respectively. The areas of ablation zone in the in vivo experiment were <inline-formula> <tex-math notation="LaTeX">$56.35~\pm ~5.93$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$63.52~\pm ~13.73$ </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">$80.82~\pm ~11.91$ </tex-math></inline-formula> mm2 following the EP of 0, 375, and 750 V/cm, respectively. Correspondingly, the ablation zone in the computer simulation was increased to 73.26 mm2 with an EP of 750 V/cm compared to 50.97 mm2 with no EP. The study concludes that the ablation effectiveness of RFA can be enhanced by EP treatment just prior to RFA, and the enhancement positively correlates with the applied electric field strengths.