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 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

scholarly journals Lorentz force induced shear waves for magnetic resonance elastography applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillaume Flé ◽  
Guillaume Gilbert ◽  
Pol Grasland-Mongrain ◽  
Guy Cloutier
Keyword(s):  
Magnetic Resonance ◽  
Shear Wave ◽  
Lorentz Force ◽  
Wave Attenuation ◽  
Shear Waves ◽  
Estimation Method ◽  
Biological Tissues ◽  
Magnetic Resonance Elastography ◽  
Motion Generation ◽  
Wave Source

AbstractQuantitative mechanical properties of biological tissues can be mapped using the shear wave elastography technique. This technology has demonstrated a great potential in various organs but shows a limit due to wave attenuation in biological tissues. An option to overcome the inherent loss in shear wave magnitude along the propagation pathway may be to stimulate tissues closer to regions of interest using alternative motion generation techniques. The present study investigated the feasibility of generating shear waves by applying a Lorentz force directly to tissue mimicking samples for magnetic resonance elastography applications. This was done by combining an electrical current with the strong magnetic field of a clinical MRI scanner. The Local Frequency Estimation method was used to assess the real value of the shear modulus of tested phantoms from Lorentz force induced motion. Finite elements modeling of reported experiments showed a consistent behavior but featured wavelengths larger than measured ones. Results suggest the feasibility of a magnetic resonance elastography technique based on the Lorentz force to produce an shear wave source.

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 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.

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.

Imaging of shear waves induced by Lorentz force in soft solids

2013 ◽  
Author(s):  
Pol Grasland-Mongrain ◽  
Stefan Catheline ◽  
Remi Souchon ◽  
Florian Cartellier ◽  
Ali Zorgani ◽  
...  
Keyword(s):  
Lorentz Force ◽  
Shear Waves ◽  
Soft Solids
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