Finite element modeling of tissue for optimal ultrasonic transducer array design

Tissue characterization using ultrasound scattering has been routinely used to extract the cellular properties of tissue. Ultrasonic backscattered radio frequency (RF) data is analyzed to provide estimates of the size, shape and concentration of a wide range of tissues. These tissue parameters form a feature space that can be used to discriminate between tissue types as well as indicate the presence of disease. In this work we develop numerical finite element models of tissue by using spectrum analysis to extract the acoustic properties of three distinct tissue-mimicking phantoms. The tissue-mimicking phantoms are constructed using glass microspheres of diameters 15-45 mum, 40-70 mum and 90-150 mum, embedded in a uniform concentration of gelatin derived from porcine skin. Spectrum analysis of the backscattered data from the tissue phantoms yields acoustic properties (of scatterer size, shape and distribution) which are used to create finite element models (FEM) of the tissue phantom. Simulations of acoustic scattering from an FEM phantom consisting 40 mum scatterers located in a transducer resolution cell is performed. Spectral analysis of the backscattered from the FEM phantom yields an estimate of the scatterer size of 36.7 mum giving an accuracy of 91%.