Real-time monitoring of bioelectrical impedance for minimizing tissue carbonization in microwave ablation of porcine liver

The charring tissue generated by high temperature during microwave ablation can affect the therapeutic effect, such as limiting the volume of the coagulation zone and causing rejection. This paper aimed to prevent tissue carbonization at the same time while delivering an appropriate thermal dose for effective ablations by employing a treatment protocol with real-time monitoring of bioelectrical impedance. Firstly, based on finite element simulation, the current field response under different ablation states. Next, the impedance changes measured by the electrodes were correlated to the physical state of the ablated tissue, and the degree of carbonization was monitored and controlled in real time. Finite element simulations revealed that the dielectric properties of biological tissues changed dynamically during the ablation process. The relative change rule of the electrical impedance magnitude of the ex vivo porcine liver throughout the entire MWA process and the reduction of the central region carbonization were obtained by the MWA experiment. Charring tissue was eliminated without water cooling at 40 W and significantly reduced at 50 W and 60 W. The carbonization during MWA can be reduced according to the relative change pattern of tissue electrical impedance for optimizing microwave thermal ablation efficacy.