Method and System for Automatic Estimation of Shear Modulus and Viscosity from Shear Wave Imaging

Patent metadata

Field	Value
Publication number	US-2016310107-A1
Application number	US-201514693080-A
Country	US
Kind code	A1
Filing date	Apr 22, 2015
Priority date	Apr 22, 2015
Publication date	Oct 27, 2016
Grant date	—

Abstract

A method and system for automatic non-invasive estimation of shear modulus and viscosity of biological tissue from shear-wave imaging is disclosed. Shear-wave images are acquired to evaluate the mechanical properties of an organ of a patient. Shear-wave propagation in the tissue in the shear-wave images is simulated based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation. The simulated shear-wave propagation is compared to observed shear-wave propagation in the shear-wave images of the tissue using a cost function. Patient-specific shear modulus and viscosity values for the tissue are estimated to optimize the cost function comparing the simulated shear-wave propagation to the observed shear-wave propagation.

First claim

1 . A method for estimating shear modulus and viscosity of tissue of a patient based on shear-wave images of the tissue, comprising:
simulating shear-wave propagation in the tissue based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation; comparing the simulated shear-wave propagation to observed shear-wave propagation in the shear-wave images of the tissue using a cost function; and estimating patient-specific shear modulus and viscosity values for the tissue to optimize the cost function comparing the simulated shear-wave propagation to the observed shear-wave propagation.

2 . The method of claim 1 , further comprising:
visualizing the estimated patient-specific shear modulus and viscosity values by generating spatial maps of shear modulus and viscosity.

3 . The method of claim 1 , wherein simulating shear-wave propagation in the tissue based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation comprises:
computing shear displacement of the tissue in spatial domain corresponding to at least a region of the shear-wave images at each of a plurality of time steps based on the shear modulus and viscosity values for the tissue.

4 . The method of claim 3 , wherein computing shear displacement of the tissue in spatial domain corresponding to at least a region of the shear-wave images at each of a plurality of time steps based on the shear modulus and viscosity values for the tissue comprises:
calculating the shear displacement of the tissue in the spatial domain by solving ρ∂ t 2 u=μ∇ 2 u+η∂ t ∇ 2 u at each time step, where μ is the shear modulus, η is the viscosity, ρ is a density of the tissue, and u is shear displacement of the tissue.

5 . The method of claim 1 , wherein simulating shear-wave propagation in the tissue based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation comprises:
simulating the shear-wave propagation in the tissue using the computational model of shear-wave propagation with predetermined initialized shear modulus and viscosity values for the tissue.

6 . The method of claim 1 , wherein simulating shear-wave propagation in the tissue based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation comprises:
calculating an initial shear modulus value for the tissue based on a measured shear-wave velocity in the shear-wave images under an assumption that the tissue is non-viscous; and simulating the shear-wave propagation in the tissue using the computational model of shear-wave propagation with the calculated initial shear modulus value and a predetermined initial viscosity value.

7 . The method of claim 1 , wherein simulating shear-wave propagation in the tissue based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation comprises:
determining initial boundary conditions for shear displacement in the tissue based on a number of first frames of the shear wave images; and simulating the shear-wave propagation in the tissue starting from the initial boundary conditions for the shear displacement in the tissue based on the shear modulus and viscosity values for the tissue using the computational model of shear-wave propagation.

8 . The method of claim 1 , wherein simulating shear-wave propagation in the tissue based on shear modulus and viscosity values for the tissue using a computational model of shear-wave propagation comprises:
determining initial boundary conditions for the shear-wave propagation using a direct model of an acoustic radiation force impulse (ARFI) used to generate the shear-waves in the shear-wave images, wherein the direct model of ARFI is adapted to current probe parameters of an ultrasound probe used to acquired the shear-wave images; and simulating the shear-wave propagation in the tissue starting from the initial boundary conditions based on the shear modulus and viscosity values for the tissue using the computational model of shear-wave propagation.

9 . The method of claim 1 , wherein comparing the simulated shear-wave propagation to observed shear-wave propagation in the shear-wave images of the tissue using a cost function comprises:
directly comparing a simulated shear-wave displacement to an observed shear-wave displacement at a particular time frame for a plurality of locations in a spatial domain of the shear-wave images using the cost function.

10 . The method of claim 9 , wherein directly comparing a simulated shear-wave displacement to an observed shear-wave displacement at a particular time frame for a plurality of locations in a spatial domain of the shear-wave images using the cost function comprises:
calculating a normalized cross-correlation cost function that directly compares the simulated shear-wave displacement to the observed shear-wave displacement at the particular time frame for the plurality of locations in a spatial domain of the shear-wave images.

11 . The method of claim 9 , wherein directly comparing a simulated shear-wave displacement to an observed shear-wave displacement at a particular time frame for a plurality of locations in a spatial domain of the shear-wave images using the cost function comprises:
calculating a sum of squared distance cost function that directly compares the simulated shear-wave displacement to the observed shear-wave displacement at the particular time frame for the plurality of locations in the spatial domain of the shear-wave images.

12 . The method of claim 1 , wherein comparing the simulated shear-wave propagation to observed shear-wave propagation in the shear-wave images of the tissue using a cost function comprises:
directly comparing a simulated shear-wave displacement to an observed shear-wave displacement for a particular location in a spatial domain of the shear-wave images frame at each of a plurality of time steps using the cost function.

13 . The method of claim 1 , wherein comparing the simulated shear-wave propagation to observed shear-wave propagation in the shear-wave images of the tissue using a cost function comprises:
directly comparing a simulated shear-wave displacement to an observed shear-wave displacement for each of a plurality of locations in a spatial domain of the shear-wave images frame at each of a plurality of time steps using the cost function.

14 . The method of claim 1 , wherein comparing the simulated shear-wave propagation to observed shear-wave propagation in the shear-wave images of the tissue using a cost function comprises:
calculating a cost function in a radiofrequency space that compares a measured radiofrequency shift of the observed shear-wave propagation with a computed radiofrequency shift of the simulated shear-wave propagation.

15 . The method of claim 1 , wherein estimating patient-specific shear modulus and viscosity values for the tissue to optimize the cost function comparing the simulated shear-wave propagation to the observed shear-wave propagation comprises:
estimating an initial shear modulus value and an initial viscosity value for the tissue a target region of the shear-wave images; simulating the shear-wave propagation using the computational model of shear-wave propagation with the current values for the shear modulus and viscosity of the tissue in the target region; generating an error map showing a spatial distribution of error values between the simulated shear-wave propagation using the current values for the shear modulus and viscosity and the observed

Assignees

• Siemens Corp
• Siemens Medical Solutions Usa Inc

Inventors

• Mansi Tommaso
• Rapaka Saikiran
• Kamen Ali
• Dorin Dorin
• Forlot Francois
• Fan Liexiang

Classifications

• A61B8/5223

  for extracting a diagnostic or physiological parameter from medical diagnostic data (for algorithms to analyse biomedical images G06T7/0012) · CPC title

• A61B8/5207

  involving processing of raw data to produce diagnostic data, e.g. for generating an image · CPC title

• G16H50/30

  for calculating health indices; for individual health risk assessment · CPC title

• A61B8/5269

  involving detection or reduction of artifacts · CPC title

• A61B8/485 Primary

  involving measuring strain or elastic properties · CPC title