A New Model of Ultrasonic Guided Wave Propagation in Blood Vessels and Its Propagation Characteristics

The identification of a blood vessel’s elastic properties by an ultrasonic guided wave mainly depends on the accurate propagation characteristics, which are obtained by solving the problem of elastic mechanics based on a thin-plate model. However, this method cannot accurately predict the characteristics for low frequencies. Since blood vessels are of a tubular structure, a hollow-cylinder model, constructed to model blood vessels, is proposed in this paper. Based on this model, the propagation characteristics and dispersion curves of the ultrasonic guided wave propagating along the axial direction are studied by expanding the state equation using Legendre polynomials. A detailed comparison between the results of the proposed model and the thin-layer-based model is presented. It is shown that the dispersion curves of the L (0,1) modes, calculated by the two different models, are a match for high frequencies but differ for low frequencies. The dispersion curve of the L (0,1) mode calculated by the proposed model is in good agreement with the results of the reported experiments. Then, the relationship between the propagation characteristics of ultrasonic guided waves and Young’s modulus is studied. It is discovered that the phase velocity and group velocity are significantly affected by Young’s modulus close to the cutoff frequency, which has important implications for the selection of the detection frequency to the characteristic parameter of vascular.