On Shear Wave Speed Estimation for Agar-Gelatine Phantom

Abstract

Abstract-Conventional imaging of diagnostic ultrasound is widely used. Although it makes the differences in the soft tissues echogenicities' apparent and clear, it fails in describing and estimating the soft tissue mechanical properties. It cannot portray their mechanical properties, such as the elasticity and stiffness. Estimating the mechanical properties increases chances of the identification of lesions or any pathological changes. Physicians are now characterizing the tissue's mechanical properties as diagnostic metrics. Estimating the tissue's mechanical properties is achieved by applying a force on the tissue and calculating the resulted shear wave speed. Due to the difficulty of calculating the shear wave speed precisely inside the tissue, it is estimated by analyzing ultrasound images of the tissue at a very high frame rate. In this paper, the shear wave speed is estimated using finite element analysis. A model is constructed to simulate the tissue's mechanical properties. For a generalized soft tissue model, Agar-gelatine model is used because it has properties similar to that of the soft tissue. A point force is applied at the center of the proposed model. As a result of this force, a deformation is caused. Peak displacements are tracked along the lateral dimension of the model for estimating the shear wave speed of the propagating wave using the Time-To-Peak displacement (TTP) method. Experimental results have shown that the estimated speed of the shear wave is 5.2 m/sec. The speed value is calculated according to shear wave speed equation equals about 5.7 m/sec; this means that our speed estimation system's accuracy is about 91 %, which is reasonable shear wave speed estimation accuracy with a less computational power compared to other tracking methods.

Finite Element Modelling of Corneal Biomechanics Assessment Using Ultrasonic Elastography

“…Corneal biomechanics properties are assigned to this model for different elastic moduli [43], [47]- [49]. The proposed technique is adopted from work presented in [50], [51] and represents a second step after the work presented in [52]. Corneal biomechanics are then estimated by speed of the resulting propagating shear wave.…”

Mathematical Modelling for Cornea Viscoelastic and Thermal Behavior

“…The constant load is simulated as a unit step function, and the transient load is simulated as a sinusoidal burst of 3 cycles applied for 40% of the simulation time. The transient load is chosen to be a sinusoidal burst as it simulates the acoustic radiation force burst as an internal actuator generated from an ultrasound transducer during elastography procedure [19]- [21]. The corneal tissue elasticity is set to 150 KPa to simulate a normal corneal tissue [22].…”

Impact of Post–Refractive Surgeries on Corneal Biomechanics—A Review

“…The wave speed is calculated using Equation 1. Time-of-flight, 84,85 lateral timeto-peak, 68,86 or cross-correlation 18,41,87,88 algorithms are implemented to estimate the speed of the resulting tissue deformation wave, that is, shear wave speed (SWS).…”