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Abstract: It is now accepted that an effective way to investigate the elastic properties of soft tissues is to generate a localized transient acoustic radiation force and to follow the associated displacements in the time/space domain. Shear waves induced by this stress field are particularly interesting in this kind of medium because they are governed by the shear elastic modulus μ, which is directly linked to the Young modulus, and spatial distribution and temporal evolution of the transient motion induced must therefore be obtained in detail. We report here a model based on the elastodynamic Green’s function formalism to describe these displacements. 3D simulation of radiation force in homogenous elastic media was performed and the displacement curves computed at different radial distances for different temporal force profiles. Amplitude and duration of displacement were found to be reliable parameters to characterize the elastic properties of the medium. Experimental measurements were performed in a homogeneous agar-gelatin tissue-mimicking phantom, and two transducers were used to generate the radiation force and follow the induced displacements. Displacements obtained from different lateral locations around the applied force axis were then used to reconstruct the shear-wave propagation in a scan plane as a function of time. The experimental displacements/curves agreed with the theoretical profiles obtained by the elastodynamic Green’s function formalism. [Copyright &y& Elsevier]

• Seven vibrators generate noises at [80–300] Hz and then a complex acoustic field. • S-wave speed is extracted with a 2D FFT to estimate viscoelastic parameters. • 10 iterations permit to remove outliers and ensure the repeatability of our method. In order to limit and slow the development of diseases, they have to be diagnosed early as possible to treat patients in a better and more rapid manner. In this paper, we focus on a noninvasive and quick method based on diffuse fields in elastography to detect diseases that affect the stiffness of organs. To validate our method, a phantom experiment numerically pre-validated is designed. It consists of seven vibrators that generate white noises in a bandwidth of [80–300] Hz and then a complex acoustic field in a phantom. Waves are tracked by a linear ultrasound probe L11-4v linked to a Verasonics Vantage System and are converted into a particle velocity 2D map as a function of time. The phase velocity of the shear waves is calculated using a temporal and 2D spatial Fourier transform and an adapted signal-processing method. Shear wave velocity dispersion measurement in the frequency bandwidth of the vibrators enables one to characterize the dynamic hardness of the material through the viscoelastic parameters μ and η in an acquisition time shorter than a second (T acq = 300 ms). With the aim of estimating the consistency of the method, the experiment is performed N = 10 times. The measured elastic modulus and viscous parameter that quantify the dynamic properties of the medium correspond to the expected values: μ = 1.23 ± 0.05 kPa and η = 0.51 ± 0.09 Pa∙s. [ABSTRACT FROM AUTHOR]