Coupled thermo-electro-mechanical models for thermal ablation of biological tissues and heat relaxation time effects
Abstract
Thermal ablation is a widely applied electrosurgical process in medical treatment of soft
biological tissues. Numerical modeling and simulations play an important role in prediction
of temperature distribution and damage volume during the treatment planning stage of
associated therapies. In this contribution we report a coupled thermo-electro-mechanical
model, accounting for heat relaxation time, for more accurate and precise prediction of the
temperature distribution, tissue deformation and damage volume during the thermal ablation
of biological tissues. Finite element solutions are obtained for most widely used percutaneous
thermal ablative techniques, viz., radiofrequency ablation (RFA) and microwave ablation
(MWA). Importantly, both tissue expansion and shrinkage have been considered for
modeling the tissue deformation in the coupled model of high temperature thermal ablation.
The coupled model takes into account the non-Fourier effects, considering both single-phase lag (SPL) and dual-phase-lag (DPL) models of bio-heat transfer. The temperature-dependent
electrical and thermal parameters, damage-dependent blood perfusion rate and phase change
effect accounting for tissue vaporization have been accounted for obtaining more clinically
relevant model. The proposed model predictions are found to be in good agreement against
the temperature distribution and damage volume reported by previous experimental studies.
The numerical simulation results revealed that the non-Fourier effects cause a decrease in the
predicted temperature distribution, tissue deformation and damage volume during the high
temperature thermal ablative procedures. Furthermore, the effects of different magnitudes of
phase lags of the heat flux and temperature gradient on the predicted treatment outcomes of
the considered thermal ablative modalities are also quantified and discussed in detail.