Tissue viscoelasticity imaging based on vibration of ultrasonic probe

The tissue elasticity and viscosity are important information in diagnosis. A method which estimates tissue viscoelastic modulus using shear wave by acoustic radiation force was proposed. However, since the signal to noise ration of this shear wave is low, it is difficult for this method to estimate tissue viscoelastic modulus distribution. Therefore, we propose a method which can estimate tissue viscoelastic modulus distribution. Our method uses the coupler with which the viscoelastic modulus is already known and the vibration by ultrasonic probe. We measure the strain distributions of coupler and tissue, and we estimate the viscoelastic modulus distribution from the strain ratio and the time delay between coupler strain and tissue strain. Moreover, we verified the validity of our method by phantom experiment and experiment which used the pig tissue. As a result, using our method, we can estimate the viscoelastic modulus distribution quantitatively.