Ricerc@Sapienza

In the present paper, a preliminary study for the development of a portable setup suitable for in vivo measurements of tissue dielectric properties is presented. The setup consists of a hand-held spectrum analyzer, equipped with a tracking generator to operate as a vector network analyzer, and an in-house software for the post-processing of measured parameters. The proposed setup was optimized to operate in a broad frequency band (from 500 MHz to 3 GHz), minimizing the measurement uncertainty.

Thermal ablation treatments are gaining a lot of attention in the clinics thanks to their reduced invasiveness and their capability of treating non-surgical patients. The effectiveness of these treatments and their impact in the hospital's routine would significantly increase if paired with a monitoring technique able to control the evolution of the treated area in real-time. This is particularly relevant in microwave thermal ablation, wherein the capability of treating larger tumors in a shorter time needs proper monitoring.

The knowledge of dielectric properties of biological tissue is of fundamental importance for the development of diagnostic or therapeutic applications of electromagnetic fields, as microwave imaging or microwave thermal ablation. In this paper, a quality factor is introduced to identify the soundness of measurements of dielectric properties performed with different set-ups and procedures.

This study quantitatively examines the validity of mixture formulae as models to describe the microwave-range dielectric properties of biological tissue of varying water content. Mixture formulae, specifically the Maxwell Garnett and Bruggeman models, are used to predict the dielectric properties of ex-vivo bovine muscle and liver tissue samples varying in water content. The tissues are modelled as comprising of cell and macromolecule inclusions in a water matrix.