A shear wave propagation tracking method based on Modal Assurance Criterion in acoustic radiation force impulse imaging

Changes in stiffness of soft tissue are a sign of abnormalities. Therefore, techniques capable of estimating stiffness or elasticity of tissue can contribute in the assessment of various diseases. Shear wave elasticity imaging (SWEI) is a transient method of biomedical ultrasound elastography. SWEI can be performed using a single ultrasound transducer by applying an impulsive acoustic radiation force excitation to generate shear waves, whose propagation can be monitored using ultrafast imaging with plane wave in the region of interest (ROI). In the present study, Field II was used to simulate ultrasound radiation force field generated by a linear array transducer. And the motion caused by a high intensity tone burst in a homogenous viscoelastic medium was calculated using the finite element method (FEM). Then the Modal Assurance Criterion (MAC) method was presented to track the propagation of the shear wave. To verify the simulation results, an experiment was set with a High Intensity Focused Ultrasound (HIFU) transducer and SonixTouch and DAQ system to evaluate the validity and efficiencies of the MAC method. Finally, an image of shear wave propagation can be reconstructed from the delays and amplitudes of the echoes.