Method and apparatus for determining viscoelastic parameters in tissue

An apparatus for determining viscoelastic parameters of a tissue, the apparatus comprising:

• (a) an actuator for generating a vibration signal and applying a generated vibration signal to the tissue;
• (b) a driver circuit connected to drive the actuator to generate a vibration signal having at least one frequency component;
• (c) an ultrasound imaging system configured to measure displacements at a plurality of locations within the tissue in response to the vibration signal at a plurality of times;
• and
• (d) a data processor communicatively coupled to the ultrasound imaging system and configured to determine the viscoelastic parameters of the tissue including elasticity and viscosity by fitting a finite element model of the tissue to the vibration signal and the measured displacements and solving for viscoelastic parameters of the model, wherein a value for density of each element of the model is selected and the absolute values for one or more of the viscoelastic parameters for each of the elements of the model are solved.

An apparatus for determining viscoelastic parameters of a tissue, the apparatus comprising:

• (a) an actuator for generating a vibration signal and applying a generated vibration signal to the tissue;
• (b) a driver circuit connected to drive the actuator to generate a vibration signal having at least one frequency component;
• (c) an ultrasound imaging system configured to determine tissue displacement at a plurality of locations within the tissue in response to the vibration signal at a plurality of times;
• and
• (d) a data processor communicatively coupled to the ultrasound imaging system and configured to determine the strain between two locations within the tissue from the measured displacements and to estimate the difference in relaxation-times between the two locations from the difference in the phases of the strains at the two locations.