Novel imaging method of continuous shear wave by ultrasound color flow imaging

Shear wave elastography which uses continuous shear wave excited by mechanical actuator is an effective method for the evaluation of shear visco-elastic properties of the medium. However, the accuracy of the measurement is often affected by large refraction and reflection of the shear wave. In order to improve the accuracy of elastography, real-time visualization of shear wave which propagates in tissue becomes a powerful tool, because shear wave excitation is controlled so as to produce a plane wave in ROI and the velocity is measured by taking into account of shear wave propagation. In this paper, a novel imaging method of continuous shear wave by ultrasound color flow imaging (CFI) is proposed. Shear wave wavefront is directly reconstructed as a binary pattern consisting of zero and the maximum flow velocity on CFI without adding any function to the CFI. Although two conditions are needed to obtain the image, they are not severe restrictions in most applications. Based on the imaging method, a shear wave velocity estimation by taking into account of the shear wave wavefront quality is proposed. This method is applied to the measurement of shear wave velocity of skeletal muscles.