Comparative modelling of water, saline and myocardium dielectric properties in the microwave spectrum

A two dimensional prototype of a quasi real-time microwave tomographic imaging system was constructed [Semenov, et al. (1)]. In order to correlate reconstructed microwave images with physiological changes of the tissue, theoretical analysis of the tissue dielectric properties have to be conducted. Theoretical modelling of the dielectric properties of deionized water, saline and myocardium is described. Analysis was performed at a frequency range from 0.2 to 6.0GHz and In temperature range between 32°C and 48°C. Dielectric properities of water were described on the basis of the Debay theory of relaxation as a one compound relaxation process. An ion conduction component was added to the imaginary part of the Debay equation for saline dielectric properties modelling. In addition to this, free water, bound water and protein components with correspondent volume fractions were added into the dielectric relaxation model of the myocardium. Water, saline and myocardium models were compared on the basis of experimental data fitting. The deviation between our model and experimental data was about 1.5% for both e\´ and e" for deionized water. Corresponding values for saline was about 2.0% and for myocardium was about 2.5%. These models were tested in various experiments with saline, diluted saline and myocardium. Information about the biophysical parameters of the samples was theoretically determined by our models. These parameters correlated with independently measured physiological data which allowed us to utilize the model for experimental data analysis at a frequency range from 0.2GHz to 6.0GHz.