Broadband Microwave Electroporation Device for the Analysis of the Influence of Frequency, Temperature and Electrical Field Strength.

In this paper, a broadband microwave device for cell poration is presented, that enables the analysis of the relation between frequency, electrical field strengths and temperature for a successful cell poration. Electromagnetic-thermal coupled simulations in the frequency range from 1 GHz to 10 GHz show that the device reaches electrical field strengths of 100 V/cm and temperatures lower then 40°C. Electroporation experiments with adherent C2C12 mouse myoblast cells show successful uptake of an anti-histone γ -H2A.X nanobody at a frequency of 10 GHz. This MWP device allows the fast electro-poration of adherent cells. After 15 min, the cells show uptake of γ -H2A.X-specific nanobody while most of them survived.

Numerical Optimization of an Open-Ended Coaxial Slot Applicator for the Detection and Microwave Ablation of Tumors.

A multiobjective optimization method for a dual-mode microwave applicator is proposed. Dual-modality means that microwaves are used apart from the treatment, and also for the monitoring of the microwave ablation intervention. (1) The use of computational models to develop and improve microwave ablation applicator geometries is essential for further advances in this field. (2) Numerical electromagnetic-thermal coupled simulation models are used to analyze the performance of the dual-mode applicator in liver tissue; the sensitivity evaluation of the dual-mode applicator's sensing mode constrains the set of optimal solutions. (3) Three Pareto-optimal design parameter sets are derived that are optimal in terms of applicator efficiency as well as volume and sphericity of the ablation zone. The resulting designs of the dual-mode applicator provide a suitable sensitivity to distinguish between healthy and tumorous liver tissue. (4) The optimized designs are presented and numerically characterized. An improvement on the performance of previously proposed dual-mode applicator designs is achieved. The multiphysical simulation model of electromagnetic and thermal properties of the applicator is applicable for future comprehensive design procedures.

Ex vivo validation of microwave thermal ablation simulation using different flow coefficients in the porcine liver.

The purpose of the study was to validate the simulation model for a microwave thermal ablation in ex vivo liver tissue. The study aims to show that heat transfer due to the flow of tissue water during ablation in ex vivo tissue is not negligible. Ablation experiments were performed in ex vivo porcine liver with microwave powers of 60 W to 100 W. During the procedure, the temperature was recorded in the liver sample at different distances to the applicator using a fiber-optic thermometer. The position of the probes was identified by CT imaging and transferred to the simulation. The simulation of the heat distribution in the liver tissue was carried out with the software CST Studio Suite. The results of the simulation with different flow coefficients were compared with the results of the ablation experiments using the Bland-Altman analysis. The analysis showed that the flow coefficient of 90,000 W/(K*m3) can be considered as the most suitable value for clinically used powers. The presented simulation model can be used to calculate the temperature distribution for microwave ablation in ex vivo liver tissue.

Dual mode microwave tool for dielectric analysis and thermal ablation treatment of organic tissue.

A dual mode tool design to analyze organic tissue and locally perform thermal ablation treatment is presented. The tool is made of an array of split-ring resonators. It can operate on a sensing mode to track the relative dielectric changes from the organic tissue and on a treatment mode to perform thermal ablation at different input powers. The measurements were done with phantoms of human tissue. The tool is able to focus a hot spot of approximately 0.2mm with a temperature of 109 °C at an input power of 10W.