scholarly journals Requirements for accurate estimation of anisotropic material parameters by magnetic resonance elastography: A computational study

2017 ◽  
Vol 78 (6) ◽  
pp. 2360-2372 ◽  
Author(s):  
D.J. Tweten ◽  
R.J. Okamoto ◽  
P.V. Bayly
Keyword(s):  
Magnetic Resonance ◽  
Anisotropic Material ◽  
Computational Study ◽  
Magnetic Resonance Elastography ◽  
Accurate Estimation ◽  
Material Parameters

Identification of Anisotropic Material Parameters in Elastic Tissue Using Magnetic Resonance Imaging of Shear Waves

2015 ◽  
Author(s):  
Dennis J. Tweten ◽  
Ruth J. Okamoto ◽  
John L. Schmidt ◽  
Joel R. Garbow ◽  
Philip V. Bayly
Keyword(s):  
Magnetic Resonance ◽  
Parameter Identification ◽  
Shear Wave ◽  
Material Properties ◽  
Anisotropic Material ◽  
Shear Waves ◽  
Material Model ◽  
Elastic Tissue ◽  
Shear Wave Speed ◽  
Material Parameters

This paper describes the application of a material parameter identification method based on elastic shear wave propagation to simulated and experimental data from magnetic resonance elastography (MRE). In MRE, the displacements of traveling transverse and longitudinal waves in elastic, biological tissue are captured as complex 3D images. Typically, the magnitude of these waves is small, and the equations of waves in linear elastic media can be used to estimate the material properties of tissue, such as internal organs, muscle, and the brain. Of particular interest are fibrous tissues which have anisotropic properties. In this paper, an anisotropic material model with three material parameters (shear modulus, shear anisotropy, and tensile anisotropy) is the basis for parameter identification. This model relates shear wave speed, propagation direction, and polarization to the material properties. A directional filtering approach is applied to isolate the speed and polarization of shear waves propagating in multiple directions. The material properties are then estimated from the material model and isolated shear waves using weighted least squares.

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.

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