The dielectric properties of tissues have been extracted from the literature of the past five decades and presented in a graphical format. The purpose is to assess the current state of knowledge, expose the gaps there are and provide a basis for the evaluation and analysis of corresponding data from an on-going measurement programme.

/pdf/the-dielectric-properties-of-biological-tissues-i-literature-2m4c4enqvy.pdf

The dielectric properties of biological tissues: I. Literature survey

: Knowledge of the dielectric properties of biological materials is of importance in solving electromagnetic interaction problems. There is, as yet, no consensus on such data among scientists dealing with these issues. This project is geared towards producing a database of dielectric data based on measurements using recently developed techniques. This has been achieved through measurement over a wide frequency range. The new data were evaluated by comparison with corresponding data from the literature where available. To facilitate the incorporation of the dielectric data in numerical solutions, their frequency dependence was modelled to a spectrum characterised by 4 dispersion regions. The conductivity of tissues below 100 Hz was estimated from the recent measurements mitigated by data from the literature and used to estimate the body and of various body parts.

/pdf/compilation-of-the-dielectric-properties-of-body-tissues-at-1ajy1tdg3q.pdf

Compilation of the Dielectric Properties of Body Tissues at RF and Microwave Frequencies.

The development of microwave breast cancer detection and treatment techniques has been driven by reports of substantial contrast in the dielectric properties of malignant and normal breast tissues. However, definitive knowledge of the dielectric properties of normal and diseased breast tissues at microwave frequencies has been limited by gaps and discrepancies across previously published studies. To address these issues, we conducted a large-scale study to experimentally determine the ultrawideband microwave dielectric properties of a variety of normal, malignant and benign breast tissues, measured from 0.5 to 20 GHz using a precision open-ended coaxial probe. Previously, we reported the dielectric properties of normal breast tissue samples obtained from reduction surgeries. Here, we report the dielectric properties of normal (adipose, glandular and fibroconnective), malignant (invasive and non-invasive ductal and lobular carcinomas) and benign (fibroadenomas and cysts) breast tissue samples obtained from cancer surgeries. We fit a one-pole Cole-Cole model to the complex permittivity data set of each characterized sample. Our analyses show that the contrast in the microwave-frequency dielectric properties between malignant and normal adipose-dominated tissues in the breast is considerable, as large as 10:1, while the contrast in the microwave-frequency dielectric properties between malignant and normal glandular/fibroconnective tissues in the breast is no more than about 10%.

https://iopscience.iop.org/article/10.1088/0031-9155/52/20/002/pdf

A large-scale study of the ultrawideband microwave dielectric properties of normal, benign and malignant breast tissues obtained from cancer surgeries

The efficacy of emerging microwave breast cancer detection and treatment techniques will depend, in part, on the dielectric properties of normal breast tissue. However, knowledge of these properties at microwave frequencies has been limited due to gaps and discrepancies in previously reported small-scale studies. To address these issues, we experimentally characterized the wideband microwave-frequency dielectric properties of a large number of normal breast tissue samples obtained from breast reduction surgeries at the University of Wisconsin and University of Calgary hospitals. The dielectric spectroscopy measurements were conducted from 0.5 to 20 GHz using a precision openended coaxial probe. The tissue composition within the probe’s sensing region was quantified in terms of percentages of adipose, fibroconnective and glandular tissues. We fit a one-pole Cole–Cole model to the complex permittivity data set obtained for each sample and determined median Cole–Cole parameters for three groups of normal breast tissues, categorized by adipose tissue content (0–30%, 31–84% and 85–100%). Our analysis of the dielectric properties data for 354 tissue samples reveals that there is a large variation in the dielectric properties of normal breast tissue due to substantial tissue heterogeneity. We observed no statistically significant difference between the within-patient and between-patient variability in the dielectric properties. (Some figures in this article are in colour only in the electronic version)

/pdf/a-large-scale-study-of-the-ultrawideband-microwave-4iavso4ia6.pdf

A large-scale study of the ultrawideband microwave dielectric properties of normal breast tissue obtained from reduction surgeries.

This article outlines the main features of active, passive, and hybrid systems under investigation for breast cancer detection. Our main focus is on active microwave systems, in particular microwave tomography and confocal microwave imaging.

Enhancing breast tumor detection with near-field imaging

Complex permittivities of in vitro diseased and undiseased human female breast tissues have been measured at 3.2 GHz using a resonant cavity technique. Ranges of dielectric properties and water contents of these tissues are presented. Experimental data are compared with models predicted from mixture equations. Measured permittivity data lie within limits set by two-phase mixture theory, but some conductivity data are in excess of those expected for a mixture of saline and protein. At any particular microwave frequency in all tissue of a given type, the relationship between permittivity and conductivity may be parametrized using the Debye relaxation equations. For each breast tissue type a characteristic relaxation frequency was calculated and found to be lower than that of physiological saline at the same temperature. It is concluded that the dielectric relaxation of tissue water is not the only dispersive process occurring at this frequency: dielectric relaxation of bound water and the tail end of a beta-dispersion may also contribute to the dielectric properties. The similarity of the dielectric properties of benign and malignant breast tumours measured in this work suggest that in vivo dielectric imaging methods will not be capable of distinguishing them.

https://iopscience.iop.org/article/10.1088/0031-9155/37/1/014/pdf

Dielectric properties of female human breast tissue measured in vitro at 3.2 GHz

A resonant cavity perturbation technique has been developed which provides a quick, simple and accurate method of measuring the microwave dielectric properties of small, easily prepared samples of tissues, tissue-simulating materials and biological fluids. The method gives dielectric properties averaged over the sample volume. The measurement accuracy with the apparatus used is +/- 2.2% for relative permittivity and +/- 3.5% for the loss factor for most tissue and biological material samples. With appropriate basic microwave equipment the method can be applied over the 1.5-6 GHz range of frequencies of interest for active and radiometric tissue microwave imaging.

http://iopscience.iop.org/article/10.1088/0031-9155/37/1/013/pdf

D V Land

Papers

Dielectric properties of female human breast tissue measured in vitro at 3.2 GHz

A quick accurate method for measuring the microwave dielectric properties of small tissue samples.