Estimation of material parameters from slow and fast shear waves in an incompressible, transversely isotropic material

JOURNAL OF BIOMECHANICS

卷:48

Article

Tweten, Dennis J.¹  Okamoto, Ruth J.¹  Schmidt, John L.¹  Garbow, Joel R.²  Bayly, Philip V.^1,3 

[1] Washington Univ, Dept Mech Engn & Mat Sci, St Louis, MO 63130 USA

[2] Washington Univ, Dept Radiol, St Louis, MO 63130 USA

[3] Washington Univ, Dept Biomed Engn, St Louis, MO 63130 USA

关键词: MR elastography;    Shear waves;    Anisotropy;    Transversely isotropic material;    Inversion algorithms;   

DOI  :  10.1016/j.jbiomech.2015.09.009

来源: Elsevier

【 摘 要 】

This paper describes a method to estimate mechanical properties of soft, anisotropic materials from measurements of shear waves with specific polarization and propagation directions. This method is applicable to data from magnetic resonance elastography (MRE), which is a method for measuring shear waves in live subjects or in vitro samples. Here, we simulate MRE data using finite element analysis. A nearly incompressible, transversely isotropic (Ill) material model with three parameters (shear modulus, shear anisotropy, and tensile anisotropy) is used, which is appropriate for many fibrous, biological tissues. Both slow and fast shear waves travel concurrently through such a material with speeds that depend on the propagation direction relative to fiber orientation. A three-parameter estimation approach based on directional filtering and isolation of slow and fast shear wave components (directional filter inversion, or DFI) is introduced. Wave speeds of each isolated shear wave component are estimated using local frequency estimation (LFE), and material properties are calculated using weighted least squares. Data from multiple finite element simulations are used to assess the accuracy and reliability of DFI for estimation of anisotropic material parameters. (C) 2015 Elsevier Ltd. All rights reserved.

【 授权许可】

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