Objective.To date, measurement of the conductivity and relative permittivity properties of anisotropic biological tissues using electrical impedance myography (EIM) has only been possible through an invasiveex vivobiopsy procedure. Here, we present a novel forward and inverse theoretical modeling framework to estimate these properties combining surface and needle EIM measurements.Methods. The framework here presented models the electrical potential distribution within a monodomain, homogeneous, and three-dimensional anisotropic tissue. Finite-element method (FEM) simulations and tongue experimental results verify the validity of our method to reverse-engineer three-dimensional conductivity and relative permittivity properties from EIM measurements.Results. FEM-based simulations confirm the validity of our analytical framework, with relative errors between analytical predictions and simulations smaller than 0.12% and 2.6% in a cuboid and tongue model, respectively. Experimental results confirm qualitative differences in the conductivity and the relative permittivity properties in thex,y, andzdirections.Conclusion. Our methodology enables EIM technology to reverse-engineer the anisotropic tongue tissue conductivity and relative permittivity properties, thus unfolding full forward and inverse EIM predictability capabilities.Significance. This new method of evaluating anisotropic tongue tissue will lead to a deeper understanding of the role of biology necessary for the development of new EIM tools and approaches for tongue health measurement and monitoring.
Keywords: anisotropy; electrical impedance myography; tongue.
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