Abstract: Ultrasound radiation using a single tone burst pulse is applied to a selected location in a tissue region. The induced shear wave is detected in the region and its spectral distribution is calculated and analyzed. This detection may be repeated with other excitation pulses having different widths or different shapes at the same location. The spectral analysis of the detected shear wave is performed according to a nonlinear shear model for solving nonlinearity and viscoelasticity of the tissue at a single location. The detection location can be at one point at a time for imaging two-dimensional or three-dimensional tissue nonlinearities and shear wave properties including nonlinear magnitude variations, nonlinear phase variations, nonlinear coefficients, and viscoelasticity.

Abstract: Methods and apparatus measuring tissue nonlinear shear wave property are disclosed. When tissue shear responses are different to ultrasound radiation forces generated by pulses having different shapes, its nonlinear effect can be used to estimate tissue property at single location without measurements of group velocities or phase velocities. Ultrasound radiation force using a single tone burst pulse is applied to a selected location in a tissue region. The induced shear wave is detected in the region and its spectral distribution is calculated and analyzed. This detection may be repeated with other excitation pulses having different widths or different shapes at the same location. The spectral analysis of the detected shear wave is performed according to a nonlinear shear model for solving nonlinearity and viscoelasticity of the tissue at a single location in a tissue region.