Finding consensus among rheological models for shear waves in soft tissues

2020 ◽  
Vol 148 (4) ◽  
pp. 2597-2597
Author(s):  
Thomas L. Szabo ◽  
Kevin J. Parker ◽  
Sverre Holm
Keyword(s):  
Soft Tissues ◽  
Shear Waves ◽  
Rheological Models

scholarly journals Contactless remote induction of shear waves in soft tissues using a transcranial magnetic stimulation device

2016 ◽  
Vol 61 (6) ◽  
pp. 2582-2593 ◽  
Author(s):  
Pol Grasland-Mongrain ◽  
Erika Miller-Jolicoeur ◽  
An Tang ◽  
Stefan Catheline ◽  
Guy Cloutier
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Soft Tissues ◽  
Shear Waves

scholarly journals Wave Propagation in a Fractional Viscoelastic Tissue Model: Application to Transluminal Procedures

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2778
Author(s):  
Antonio Gomez ◽  
Guillermo Rus ◽  
Nader Saffari
Keyword(s):  
Wave Propagation ◽  
Soft Tissue ◽  
Imaging Modality ◽  
Shear Waves ◽  
Fdtd Method ◽  
Propagation Model ◽  
Rheological Models ◽  
New Type ◽  
Difference Time ◽  
Wave Propagation Model

In this article, a wave propagation model is presented as the first step in the development of a new type of transluminal procedure for performing elastography. Elastography is a medical imaging modality for mapping the elastic properties of soft tissue. The wave propagation model is based on a Kelvin Voigt Fractional Derivative (KVFD) viscoelastic wave equation, and is numerically solved using a Finite Difference Time Domain (FDTD) method. Fractional rheological models, such as the KVFD, are particularly well suited to model the viscoelastic response of soft tissue in elastography. The transluminal procedure is based on the transmission and detection of shear waves through the luminal wall. Shear waves travelling through the tissue are perturbed after encountering areas of altered elasticity. These perturbations carry information of medical interest that can be extracted by solving the inverse problem. Scattering from prostate tumours is used as an example application to test the model. In silico results demonstrate that shear waves are satisfactorily transmitted through the luminal wall and that echoes, coming from reflected energy at the edges of an area of altered elasticity, which are feasibly detectable by using the transluminal approach. The model here presented provides a useful tool to establish the feasibility of transluminal procedures based on wave propagation and its interaction with the mechanical properties of the tissue outside the lumen.

scholarly journals Viscoelasticity Imaging of Biological Tissues and Single Cells Using Shear Wave Propagation

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongliang Li ◽  
Guillaume Flé ◽  
Manish Bhatt ◽  
Zhen Qu ◽  
Sajad Ghazavi ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Soft Tissues ◽  
Acoustic Radiation ◽  
Single Cells ◽  
Shear Waves ◽  
Mechanical Vibration ◽  
Shear Wave Elastography ◽  
Biomechanical Properties ◽  
Biological Tissues

Changes in biomechanical properties of biological soft tissues are often associated with physiological dysfunctions. Since biological soft tissues are hydrated, viscoelasticity is likely suitable to represent its solid-like behavior using elasticity and fluid-like behavior using viscosity. Shear wave elastography is a non-invasive imaging technology invented for clinical applications that has shown promise to characterize various tissue viscoelasticity. It is based on measuring and analyzing velocities and attenuations of propagated shear waves. In this review, principles and technical developments of shear wave elastography for viscoelasticity characterization from organ to cellular levels are presented, and different imaging modalities used to track shear wave propagation are described. At a macroscopic scale, techniques for inducing shear waves using an external mechanical vibration, an acoustic radiation pressure or a Lorentz force are reviewed along with imaging approaches proposed to track shear wave propagation, namely ultrasound, magnetic resonance, optical, and photoacoustic means. Then, approaches for theoretical modeling and tracking of shear waves are detailed. Following it, some examples of applications to characterize the viscoelasticity of various organs are given. At a microscopic scale, a novel cellular shear wave elastography method using an external vibration and optical microscopy is illustrated. Finally, current limitations and future directions in shear wave elastography are presented.

scholarly journals Transcranial Focused Ultrasound Generates Skull-Conducted Shear Waves: Computational Model and Implications for Neuromodulation

2020 ◽  
Author(s):  
Hossein Salahshoor ◽  
Mikhail G. Shapiro ◽  
Michael Ortiz
Keyword(s):  
Focused Ultrasound ◽  
Soft Tissues ◽  
Control Strategies ◽  
Shear Waves ◽  
Element Model ◽  
Potential Method ◽  
Non Invasive ◽  
Auditory Responses ◽  
Shear Compliance ◽  
Established Technique

ABSTRACTFocused ultrasound (FUS) is an established technique for non-invasive surgery and has recently attracted considerable attention as a potential method for non-invasive neuromodulation. While the pressure waves generated by FUS in this context have been extensively studied, the accompanying shear waves are often neglected due to the relatively high shear compliance of soft tissues. However, in bony structures such as the skull, acoustic pressure can also induce significant shear waves that could propagate outside the ultrasound focus. Here, we investigate wave propagation in the human cranium by means of a finite-element model that accounts for the anatomy, elasticity and viscoelasticity of the skull and brain. We show that, when a region on the frontal lobe is subjected to FUS, the skull acts as a wave guide for shear waves, resulting in their propagation to off-target structures such as the cochlea. This effect helps explain the off-target auditory responses observed during neuromodulation experiments and informs the development of mitigation and sham control strategies.

Shear waves induced by Lorentz force in soft tissues

2014 ◽  
Vol 136 (4) ◽  
pp. 2279-2279
Author(s):  
Stefan Catheline ◽  
Graland-Mongrain Pol ◽  
Ali Zorgani ◽  
Remi Souchon ◽  
Cyril Lafon ◽  
...  
Keyword(s):  
Lorentz Force ◽  
Soft Tissues ◽  
Shear Waves

scholarly journals Towards a consensus on rheological models for elastography in soft tissues

2019 ◽  
Vol 64 (21) ◽  
pp. 215012 ◽  
Author(s):  
K J Parker ◽  
T Szabo ◽  
S Holm
Keyword(s):  
Soft Tissues ◽  
Rheological Models

scholarly journals Numerical Simulation of Focused Shock Shear Waves in Soft Solids and a Two-Dimensional Nonlinear Homogeneous Model of the Brain

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
B. Giammarinaro ◽  
F. Coulouvrat ◽  
G. Pinton
Keyword(s):  
Shock Wave ◽  
Numerical Methods ◽  
Shock Waves ◽  
Scaling Laws ◽  
Soft Tissues ◽  
Shear Waves ◽  
Homogeneous Model ◽  
Nonlinear Propagation ◽  
Soft Solids ◽  
The Brain

Shear waves that propagate in soft solids, such as the brain, are strongly nonlinear and can develop into shock waves in less than one wavelength. We hypothesize that these shear shock waves could be responsible for certain types of traumatic brain injuries (TBI) and that the spherical geometry of the skull bone could focus shear waves deep in the brain, generating diffuse axonal injuries. Theoretical models and numerical methods that describe nonlinear polarized shear waves in soft solids such as the brain are presented. They include the cubic nonlinearities that are characteristic of soft solids and the specific types of nonclassical attenuation and dispersion observed in soft tissues and the brain. The numerical methods are validated with analytical solutions, where possible, and with self-similar scaling laws where no known solutions exist. Initial conditions based on a human head X-ray microtomography (CT) were used to simulate focused shear shock waves in the brain. Three regimes are investigated with shock wave formation distances of 2.54 m, 0.018 m, and 0.0064 m. We demonstrate that under realistic loading scenarios, with nonlinear properties consistent with measurements in the brain, and when the shock wave propagation distance and focal distance coincide, nonlinear propagation can easily overcome attenuation to generate shear shocks deep inside the brain. Due to these effects, the accelerations in the focal are larger by a factor of 15 compared to acceleration at the skull surface. These results suggest that shock wave focusing could be responsible for diffuse axonal injuries.

scholarly journals Imaging of Shear Waves Induced by Lorentz Force in Soft Tissues

2014 ◽  
Vol 113 (3) ◽  
Author(s):  
P. Grasland-Mongrain ◽  
R. Souchon ◽  
F. Cartellier ◽  
A. Zorgani ◽  
J. Y. Chapelon ◽  
...  
Keyword(s):  
Lorentz Force ◽  
Soft Tissues ◽  
Shear Waves
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