Low-frequency shear wave beam forming in time-resolved 2D pulsed elastography

Abstract

We have shown in the past that time-resolved 2D pulsed elastography is a promising technique for characterizing the elasticity of soft tissues. It involves the measurement of the displacements induced by the propagation of a low-frequency (50-200 Hz) pulsed shear wave. An ultrafast ultrasonic imaging system (up to 10,000 frames/s) is used to follow the propagation of the slowly propagating shear wave (celerity /spl sim/4 m/s). A new vibrating device has been developed in which the linear array of transducers is placed between two rods fixed to electromagnetic vibrators. Using this device we observe a linear shear wave front in the imaging area. Furthermore the new system allows for low-frequency shear wave beam forming. The results of inversion algorithms indicate that it is possible to recover the elasticity distribution in tissue mimicking materials.