Characterization and Analysis of Wideband Temperature-Dependent Dielectric Properties of Liver Tissue for Next-Generation Minimally Invasive Microwave Tumor Ablation Technology

Microwave ablation (MWA) is a minimally invasive thermal therapy that delivers microwave energy to a malignant tumor via an interstitial antenna. To date, MWA systems have primarily operated at 915 MHz or 2.45 GHz. Knowledge of the temperature-dependent tissue dielectric properties at frequencies above 2.45 GHz is essential for future development of MWA systems that leverage advantageous antenna design and ablation performance characteristics at higher frequencies. This information is also critical for the development of real-time microwave sensing techniques for MWA monitoring. We report measured and modeled wideband (0.5-20 GHz) temperature-dependent (25-93°C) dielectric properties of ex vivo porcine liver tissue during MWA. The temperature-dependent dielectric properties were modeled using two-pole Debye models with temperature-dependent parameters described by third-order polynomials. The results address a gap in present knowledge of properties over both a wide frequency band and wide range of temperatures relevant to MWA.