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.

Radiation force of ultrasound as shear wave source in microscopic magnetic resonance elastography

2005 ◽  
Vol 118 (3) ◽  
pp. 2006-2006
Author(s):  
Shadi F. Othman ◽  
M. Bulent Ozer ◽  
Huihui Xu ◽  
Thomas J. Royston ◽  
Richard L. Magin
Keyword(s):  
Magnetic Resonance ◽  
Shear Wave ◽  
Radiation Force ◽  
Magnetic Resonance Elastography ◽  
Wave Source

scholarly journals Rescaled Local Interaction Simulation Approach for Shear Wave Propagation Modelling in Magnetic Resonance Elastography

2016 ◽  
Vol 2016 ◽  
pp. 1-12
Author(s):  
Z. Hashemiyan ◽  
P. Packo ◽  
W. J. Staszewski ◽  
T. Uhl
Keyword(s):  
Wave Propagation ◽  
Magnetic Resonance ◽  
Shear Wave ◽  
Soft Tissues ◽  
Biological Tissues ◽  
Magnetic Resonance Elastography ◽  
Local Interaction ◽  
Simulation Approach ◽  
Interaction Simulation ◽  
Propagation Modelling

Properties of soft biological tissues are increasingly used in medical diagnosis to detect various abnormalities, for example, in liver fibrosis or breast tumors. It is well known that mechanical stiffness of human organs can be obtained from organ responses to shear stress waves through Magnetic Resonance Elastography. The Local Interaction Simulation Approach is proposed for effective modelling of shear wave propagation in soft tissues. The results are validated using experimental data from Magnetic Resonance Elastography. These results show the potential of the method for shear wave propagation modelling in soft tissues. The major advantage of the proposed approach is a significant reduction of computational effort.

scholarly journals Needle shear wave driver for magnetic resonance elastography

2006 ◽  
Vol 55 (5) ◽  
pp. 1175-1179 ◽  
Author(s):  
Q.C.C. Chan ◽  
G. Li ◽  
R.L. Ehman ◽  
R.C. Grimm ◽  
R. Li ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Shear Wave ◽  
Magnetic Resonance Elastography

scholarly journals Shear Wave Elastography Based on Noise Correlation and Time Reversal

2021 ◽  
Vol 9 ◽  
Author(s):  
Javier Brum ◽  
Nicolás Benech ◽  
Thomas Gallot ◽  
Carlos Negreira
Keyword(s):  
Shear Wave ◽  
Time Reversal ◽  
Shear Waves ◽  
Shear Wave Elastography ◽  
Noise Correlation ◽  
Elasticity Imaging ◽  
Physiological Noise ◽  
Wave Source ◽  
Imaging Device ◽  
Shear Elasticity

Shear wave elastography (SWE) relies on the generation and tracking of coherent shear waves to image the tissue's shear elasticity. Recent technological developments have allowed SWE to be implemented in commercial ultrasound and magnetic resonance imaging systems, quickly becoming a new imaging modality in medicine and biology. However, coherent shear wave tracking sets a limitation to SWE because it either requires ultrafast frame rates (of up to 20 kHz), or alternatively, a phase-lock synchronization between shear wave-source and imaging device. Moreover, there are many applications where coherent shear wave tracking is not possible because scattered waves from tissue’s inhomogeneities, waves coming from muscular activity, heart beating or external vibrations interfere with the coherent shear wave. To overcome these limitations, several authors developed an alternative approach to extract the shear elasticity of tissues from a complex elastic wavefield. To control the wavefield, this approach relies on the analogy between time reversal and seismic noise cross-correlation. By cross-correlating the elastic field at different positions, which can be interpreted as a time reversal experiment performed in the computer, shear waves are virtually focused on any point of the imaging plane. Then, different independent methods can be used to image the shear elasticity, for example, tracking the coherent shear wave as it focuses, measuring the focus size or simply evaluating the amplitude at the focusing point. The main advantage of this approach is its compatibility with low imaging rates modalities, which has led to innovative developments and new challenges in the field of multi-modality elastography. The goal of this short review is to cover the major developments in wave-physics involving shear elasticity imaging using a complex elastic wavefield and its latest applications including slow imaging rate modalities and passive shear elasticity imaging based on physiological noise correlation.

scholarly journals Magnetic resonance elastography of slow and fast shear waves illuminates differences in shear and tensile moduli in anisotropic tissue

2016 ◽  
Vol 49 (7) ◽  
pp. 1042-1049 ◽  
Author(s):  
J.L. Schmidt ◽  
D.J. Tweten ◽  
A.N. Benegal ◽  
C.H. Walker ◽  
T.E. Portnoi ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Shear Waves ◽  
Magnetic Resonance Elastography

Validation of Magnetic Resonance Elastography by Dynamic Shear Testing in the Shear Wave Regime

2010 ◽  
Author(s):  
Ruth J. Okamoto ◽  
Erik H. Clayton ◽  
Kate S. Wilson ◽  
Philip V. Bayly
Keyword(s):  
Magnetic Resonance ◽  
Shear Modulus ◽  
Shear Wave ◽  
Shear Force ◽  
Magnetic Resonance Elastography ◽  
Dynamic Shear ◽  
Complex Shear Modulus ◽  
Shear Testing ◽  
Complex Shear ◽  
Propagating Shear

Magnetic resonance elastography (MRE) is a novel experimental technique for probing the dynamic shear modulus of soft biological tissue non-invasively and in vivo. MRE utilizes a standard MRI scanner to acquire images of propagating shear waves through a specimen that is subject to external harmonic mechanical actuation; commonly at frequencies in excess of 200Hz. At steady state, the wavelength of the propagating shear wave can be used to estimate the shear modulus of the tissue. Dynamic shear testing (DST) is also used to characterize soft biomaterials. Thin samples of the material are subject to oscillatory shear strains. Shear force is measured, and converted to shear stress — analysis of this data of a range of frequencies gives a complex shear modulus. The data analysis method assumes that the shear displacement is linear and shear strain is constant through the thickness of the sample. In soft tissues, very thin samples are typically used to avoid inertial effects at higher frequencies. As the thickness of the sample decreases, it is more difficult to cut samples of uniform thickness and to maintain structural integrity of the sample. Thus in practice, measurements of brain tissue properties using DST without inertial correction are limited to low frequencies. In this work, we bridge the frequency regimes of DST and MRE by testing thick samples using DST over a range of frequencies that generates a shear wave in the sample, with a corresponding peak in the measured shear force. The frequency and magnitude of this peak give additional information about the complex shear modulus of the material being tested, and these DST results are interpreted using a finite element (FE) model of the sample. Using this method, we can obtain an estimate of shear modulus in an intermediate frequency regime between that of standard DST and MRE.

scholarly journals Modeling and Simulation of Head Trauma Utilizing White Matter Properties from Magnetic Resonance Elastography

Modelling ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 225-241
Author(s):  
Amit Madhukar ◽  
Martin Ostoja-Starzewski
Keyword(s):  
White Matter ◽  
Magnetic Resonance ◽  
Shear Wave ◽  
Mechanical Response ◽  
Material Model ◽  
Magnetic Resonance Elastography ◽  
Head Model ◽  
Fe Model ◽  
Inversion Algorithm ◽  
Hyper Elastic

Tissues of the brain, especially white matter, are extremely heterogeneous—with constitutive responses varying spatially. In this paper, we implement a high-resolution Finite Element (FE) head model where heterogeneities of white matter structures are introduced through Magnetic Resonance Elastography (MRE) experiments. Displacement of white matter under shear wave excitation is captured and the material properties determined through an inversion algorithm are incorporated in the FE model via a two-term Ogden hyper-elastic material model. This approach is found to improve model predictions when compared to experimental results. In the first place, mechanical response in the cerebrum near stiff structures such as the corpus callosum and corona radiata are markedly different compared with a homogenized material model. Additionally, the heterogeneities introduce additional attenuation of the shear wave due to wave scattering within the cerebrum.

Sign in / Sign up

Export Citation Format

Share Document