Nowadays ultrasound-based non-invasive techniques for the evaluation of tissue elasticity are becoming increasingly popular. A key determinant adequate treatment focal liver lesions is on establishment accurate diagnosis. Contemporary imaging modalities, particularly ultrasonographic, widely accepted assessing but investigation their accuracy and differentiation potential still ongoing. Aim: To...

The generation of shear waves from an ultrasound focused beam has been developed as a major concept for remote palpation using shear wave elastography (SWE). For muscular diagnostic applications, characteristics of the shear wave profile will strongly depend on characteristics of the transducer as well as the orientation of muscular fibers and the tissue viscoelastic properties. The numerical s...

The objective of this thesis is to develop a rigorous mathematical and numerical background for the extension and dissemination of imaging modalities by ultrasound, i.e. elastic waves, applied to the cardiac settings. The problems treated will concerned the topics of mathematical modeling, numerical analysis and scientific computing. More precisely we plan to define a linearized model for the p...

Introduction: Magnetic resonance elastography (MRE) allows the measurement of the mechanical properties of living tissue by combining shear waves and motion sensitive MRI [1]. In classical MRE, shear wave images are evaluated using an appropriate wave inversion technique for calculating an estimate of the spatial distribution of the shear modulus within the region of interest [2]. Problem: Wave...

The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. The estimators can be relatively simple if plane wave beha...

Transient elastography quantifies the propagation of a mechanically generated shear wave within a soft tissue, which can be used to characterize the elasticity and viscosity parameters of the tissue. The aim of our study was to combine numerical simulation and clinical assessment to define a viscoelastic index of liver tissue to improve the quality of early diagnosis of liver fibrosis. This is ...

Elastography is a new technique for evaluating the stiffness of nodules. It is generally recognised that malignant thyroid lesions are harder than benign lesions. Different elastographic techniques are presented, with characteristics, advantages and limita‐ tions. Qualitative and semiquantitative methods are described. Comparison of the main existing techniques, static and dynamic elastographie...

For nearly 100 y in the study of cyclical motion in materials, a particular phenomenon called "linear hysteresis" or "ideal hysteretic damping" has been widely observed. More recently in the field of shear wave elastography, the basic mechanisms underlying shear wave losses in soft tissues are in question. Could linear hysteresis play a role? An underlying theoretical question must be answered:...

The Fibroscan (Echosens, Paris, France) device based on vibration–controlled transient elastography (VCTE) is used to non– invasively assess liver stiffness correlated to the hepatic fibrosis. Stiffness is quantified by measuring the velocity of a low–frequency shear wave traveling through the liver, which is proportional to the Young’s modulus E. It has been demonstrated that E is highly corre...