# Reconstruction of the Permittivity of Ex Vivo Animal Tissues in the Frequency Range 1–20 GHz Using a Water-Based Dielectric Model

## TL;DR

This paper explores using water content from ex vivo tissues to estimate their dielectric properties at frequencies between 1 and 20 GHz.

## Contribution

The novelty is verifying the feasibility of using water content to reconstruct tissue permittivity in the 1–20 GHz range.

## Key findings

- Water content was retrieved for five ex vivo tissues using a dehydration procedure.
- Results were compared with literature references to validate the method's accuracy.
- The study confirms that water content can be used to estimate dielectric properties in the specified frequency range.

## Abstract

Several medical techniques are based on the application of electromagnetic fields (EMFs) on the human body with therapeutic and/or diagnostic aims. The response of human tissues to the applied EMF is mediated by the tissues’ dielectric properties, which must therefore be characterized at the frequencies of the considered technique. Due to the heterogeneity and complexity of biological tissues, it is necessary to know their properties in vivo for the specific condition of interest. Traditional techniques for the dielectric characterization of biological tissues are invasive and, as such, not adoptable for this aim. Accordingly, alternative sensors and/or sensing methods are needed. Recently, a new wideband spectroscopy technique was proposed, based on quantities derived from the Magnetic Resonance (MRI) signal. Among these quantities, the water content was proposed to evaluate the dielectric properties at frequencies around a few GHz. This work verifies the possibility of deriving tissues’ dielectric properties in the frequency range of 1–20 GHz based on knowledge of the water content. The water content was retrieved through a dehydration procedure for five different ex vivo tissues. The achieved results were compared with references from the literature.