PURPOSE: To investigate the anisotropic elasticity of soft tissues using MR elastography (MRE) combined with diffusion tensor imaging (DTI). MATERIALS AND METHODS: The storage moduli parallel (μ(‖)) and perpendicular (μ(⊥)) to the local fiber orientation were calculated assuming a transversely isotropic model. The local fiber orientation was provided by DTI. The proposed technique was validated against rheometry using anisotropic viscoelastic phantoms with various fiber volume fractions (V(f) = 0%, 15%, and 35%) and bovine skeletal muscle samples. RESULTS: The anisotropic ratio (μ(‖)/μ(⊥)) as measured by MRE correlated well with rheometry for all samples (R(2) = 0.809). The combined MRE/DTI technique was also able to differentiate different levels of mechanical anisotropy with the mechanical anisotropy (μ(‖)/μ(⊥)) of the V(f) = 35% phantoms being significantly higher than the V(f) = 15% and the isotropic (V(f) = 0%) phantoms. The bovine muscle samples showed significantly higher mechanical anisotropy than all phantoms. CONCLUSION: This study has demonstrated the feasibility of the proposed imaging technique for characterizing mechanical anisotropy of anisotropic materials and biological tissues, and validated the mechanical anisotropy results.
PURPOSE: To investigate the anisotropic elasticity of soft tissues using MR elastography (MRE) combined with diffusion tensor imaging (DTI). MATERIALS AND METHODS: The storage moduli parallel (μ(‖)) and perpendicular (μ(⊥)) to the local fiber orientation were calculated assuming a transversely isotropic model. The local fiber orientation was provided by DTI. The proposed technique was validated against rheometry using anisotropic viscoelastic phantoms with various fiber volume fractions (V(f) = 0%, 15%, and 35%) and bovine skeletal muscle samples. RESULTS: The anisotropic ratio (μ(‖)/μ(⊥)) as measured by MRE correlated well with rheometry for all samples (R(2) = 0.809). The combined MRE/DTI technique was also able to differentiate different levels of mechanical anisotropy with the mechanical anisotropy (μ(‖)/μ(⊥)) of the V(f) = 35% phantoms being significantly higher than the V(f) = 15% and the isotropic (V(f) = 0%) phantoms. The bovine muscle samples showed significantly higher mechanical anisotropy than all phantoms. CONCLUSION: This study has demonstrated the feasibility of the proposed imaging technique for characterizing mechanical anisotropy of anisotropic materials and biological tissues, and validated the mechanical anisotropy results.
Authors: Matthew W Urban; Manuela Lopera; Sara Aristizabal; Carolina Amador; Ivan Nenadic; Randall R Kinnick; Alexander D Weston; Bo Qiang; Xiaoming Zhang; James F Greenleaf Journal: IEEE Trans Ultrason Ferroelectr Freq Control Date: 2015-06 Impact factor: 2.725
Authors: J L Schmidt; D J Tweten; A N Benegal; C H Walker; T E Portnoi; R J Okamoto; J R Garbow; P V Bayly Journal: J Biomech Date: 2016-02-15 Impact factor: 2.712
Authors: Elizabeth C Brown; Shaokoon Cheng; David K McKenzie; Jane E Butler; Simon C Gandevia; Lynne E Bilston Journal: Sleep Date: 2015-04-01 Impact factor: 5.849