Precise tracking of impulsive acoustic radiation force induced small displacements for shear wave speed estimation

2011 ◽  
Author(s):  
Yang Shen ◽  
Feiyan Cai ◽  
Yang Xiao ◽  
Tao Ling ◽  
Chengzhi Zeng ◽  
...  
Keyword(s):  
Shear Wave ◽  
Wave Speed ◽  
Acoustic Radiation ◽  
Radiation Force ◽  
Acoustic Radiation Force ◽  
Speed Estimation ◽  
Shear Wave Speed

Acoustic radiation force impulse with shear wave speed quantification of pancreatic masses: A prospective study

Pancreatology ◽  
2016 ◽  
Vol 16 (1) ◽  
pp. 106-109 ◽  
Author(s):  
Mirko D'Onofrio ◽  
Riccardo De Robertis ◽  
Stefano Crosara ◽  
Cristina Poli ◽  
Stefano Canestrini ◽  
...  
Keyword(s):  
Prospective Study ◽  
Shear Wave ◽  
Wave Speed ◽  
Acoustic Radiation ◽  
Radiation Force ◽  
Acoustic Radiation Force ◽  
Acoustic Radiation Force Impulse ◽  
Shear Wave Speed ◽  
Pancreatic Masses ◽  
A Prospective Study

Acoustic Radiation Force Creep and Shear Wave Propagation Method for Elasticity Imaging

2012 ◽  
Author(s):  
Carolina Amador ◽  
Matthew W. Urban ◽  
Shigao Chen ◽  
James F. Greenleaf
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Wave Speed ◽  
Acoustic Radiation ◽  
Radiation Force ◽  
Acoustic Radiation Force ◽  
Time Dependent ◽  
Elasticity Imaging ◽  
Shear Wave Speed ◽  
Model Independent

Elasticity imaging methods have been used to study tissue mechanical properties and have demonstrated that tissue elasticity changes with disease state. Quantitative mechanical properties can be measured in a model independent manner if both shear wave speed and attenuation are known. However, measuring shear wave speed attenuation is challenging in the field of elasticity imaging. Typically, only shear wave speed is measured and rheological models, such as Kelvin-Voigt, Maxwell and Standard Linear Solid, are used to solve for shear viscoelastic complex modulus. Acoustic radiation force has been used to study quasi-static viscoelastic properties of tissue during creep and relaxation conditions, however, as with shear wave propagation methods, a rheological model needs to be fit to the creep or relaxation experimental data to solve for viscoelastic parameters. This paper presents a method to quantify viscoelastic properties in a model-independent way by estimating complex shear elastic modulus over a wide frequency range using time-dependent creep response induced by acoustic radiation force. The acoustic radiation force induced creep (RFIC) method uses a conversion formula that is the analytic solution of the constitutive equation relating time dependent stress and time dependent strain. The RFIC method in combination with shear wave propagation is used to measure the complex shear modulus so that knowledge of the applied radiation force magnitude is not necessary. Numerical simulation of creep strain and compliance using the Kelvin-Voigt model shown that the conversion formula is sensitive to sampling frequency, the first reliable measure in time and the long term viscosity approximation. Experimental data are obtained in homogeneous tissue mimicking phantoms and excised swine kidneys.

Quantitative Images of Elastic Modulus Using Tissue Dynamics in the Region of Impulsive Acoustic Radiation Force Excitation

2009 ◽  
Author(s):  
Mark L. Palmeri ◽  
David Xu ◽  
Michael Wang ◽  
Kathryn Nightingale
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Acoustic Radiation ◽  
Simulated Data ◽  
Radiation Force ◽  
Acoustic Radiation Force ◽  
Excitation Beam ◽  
Shear Wave Speed ◽  
Shear Elasticity ◽  
Force Excitation

Focused, impulsive, acoustic radiation force excitations can generate shear waves with microns of displacement in tissue. The speed of shear wave propagation is directly related to the tissue’s shear modulus, which can be correlated with tissue pathology to diagnose disease and to follow disease progression. Shear wave speed reconstruction has conventionally been measured over spatial domains that are spatially-offset from the region of excitation (ROE). While these methods are very robust in clinical studies characterizing large, homogeneous organs, their spatial resolution can be limited when generating quantitative images of shear elasticity. The ROETTP algorithm measures time-to-peak (TTP) displacements along the axis-of-symmetry in the ROE of an impulsive acoustic radiation force excitation. These TTP displacements are inversely proportional to shear stiffness and are dependent on the excitation-beam geometry. Lookup tables (LUTs) specific to an excitation/displacement tracking transducer configuration were generated from simulated data, and shear stiffnesses were estimated from experimental data as a function of depth using the LUTs. Quantitative ROETTP shear elasticity images of spherical inclusions in a calibrated tissue-mimicking phantom have been generated. Shear wave reflections and interference can lead to an underestimation of the absolute reconstructed shear modulus (20–25%), but the ratio of absolute shear stiffnesses is well-preserved (3.3 vs. 3.5).

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