11 Tissue Harmonic Motion Estimation for Tissue Characterization Using Ultrasound and Kalman Filter

Detection of tissue harmonic motion using ultrasound is introduced for biomedical applications. The harmonic motion induced by the ultrasound radiation force in a tissue region is expressed as a Doppler frequency shift in the fast time and as an oscillatory phase shift in the slow time. A method using pulse echo ultrasound and the Kalman filter is presented for detecting the phase shifts over a short distance in a tissue region. The phase shift over a short distance is used to find the shear wave velocity, which is related to tissue stiffness. The elasticity and viscosity of tissue can be quantitatively calculated with the wave speed dispersion in frequency. Examples and experiments are shown to validate the method.