Tissue Permittivity Measurement with Concurrent CT Imaging: Analysis of Heterogeneity Effects

Tissue dielectric properties are important parameters in microwave sensing and microwave ablation as the tissue contrast and input to simulations, respectively. Coaxial probes are widely used in property measurements, however inhomogeneities in tissues might result in inconsistent measurements. To further analyze this issue, computed tomography (CT) was used to image assumed coaxial probe sensing volume in an ex-vivo lung tissue. Even though density of lung and measured permittivity had positive correlation, high variation in data suggested limitations in CT image resolution might have contributed the variation. Further analysis with simulations showed an inclusion with the width of 0.3 mm and 50% of the permittivity of the background tissue can impact measurements significantly.