RESUMEN
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 (Tacq = 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 Paâs.
