Dielectric Characterization of Ex Vivo Ovine and Human Adrenal Glands for Microwave Thermal Ablation Applications

Abstract

A graphical representation of the variability of relative permittivity and effective conductivity (S/m) of the functional tissues composing the adrenal gland and related diseases in the frequency range of the microwave thermal ablation techniques. The operating frequencies generally adopted to excite the electromagnetic field by an interstitial antenna are: 915 MHz, 2.45 GHz and 5.8 GHz. Take-Home Messages• Ovine dielectric data are collected, distinguishing between the two functional tissues composing the adrenal gland (cortex and medulla): a sizable difference between the dielectric properties of the two tissues is observed. • Optimized Cole-Cole model of the ovine dielectric properties are presented to allow integration of the data into numerical electromagnetic models. • Human data are collected considering both healthy and diseased adrenal tissues. For the first time, dielectric properties of ex vivo human adrenal glands are measured, presented and compared with data of ex vivo animal models. • The ovine adrenal gland is a feasible model for the optimization of electromagnetic based devices tackling Primary Aldosteronism, such as microwave thermal ablation devices. The ovine model electromagnetically resembles the composition of the human adrenal gland. The ovine model can potentially be adopted in preclinical studies to test the safety and performances of MWA.

RETRACTED ARTICLE: DLMBHCO: design of an augmented bioinspired deep learning-based multidomain body parameter analysis via heterogeneous correlative body organ analysis

“…In the field of medical image segmentation, CNN and other networks that have taken their cues from it have become the de facto standard due to the improved representation they provide. The transformer architecture has become an essential part of natural language processing (NLP) efforts and has attained state-of-the-art performance metrics (Wang 2022 ; Bottiglieri 2021 ; Wang 2022 ), despite the fact that it was first developed for sequence modeling. The sturdy quality of this design’s worldwide link communication capabilities is one of the reasons why it stands out.…”

MWA Performed at 5.8 GHz through ‘Side Firing’ Approach: An Exploratory Study

“…Table 1 lists the dielectric and thermal properties assigned to each layer, representing the adrenal tissues (i.e., medulla and cortex) and the external fat layer. The values of relative permittivity and effective conductivity described in [ 11 ] were assigned to the adrenal cortex and medulla. The dielectric properties assigned to the fat tissue and the thermal properties of each tissue were acquired from [ 15 ].…”

“…Contrast between the dielectric properties of the tissues of interest increases with frequency [ 10 , 11 ]. For example, the contrast in effective conductivity between the adrenal cortex and fat is nearly two-fold higher at 5.8 GHz as compared with the contrast at 2.45 GHz.…”

The Complex Permittivity of Biological Tissues: A Practical Measurement Guideline

“…In the case of heterogeneous tissues, samples can be homogenised to obtain a mean value of the dielectric properties of the MUT [63], ensuring that in the process of homogenisation no loss of hydration occurs. Accurate histology sampling may support the accurate characterisation of the tissue components composing the heterogeneity in the measured volume [64,65]. 23.…”

“…Both methods provide an indication of the properties of the whole sample. The second approach is to use histology to identify tissue content and distribution within the sample, and to use this information to interpret the dielectric data [32,64,65,[90][91][92][93]. This method is site-specific and provides information on the sample properties at one specific location on the sample.…”