title: Combining MR elastography and diffusion tensor imaging for the assessment of anisotropic mechanical properties: a phantom study.
abstract: OBJECTIVE
  To investigate the anisotropic elasticity of soft tissues using MR elastography (MRE) combined with diffusion tensor imaging (DTI).
  
  
  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.
  
  
  CONCLUSIONS
  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.affiliation: Neuroscience Research Australia, Randwick, Australia.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Qin
authors.forename: Ralph
authors.initials: R
authors.lastname: Sinkus
authors.forename: Guangqiang
authors.initials: G
authors.lastname: Geng
authors.forename: Shaokoon
authors.initials: S
authors.lastname: Cheng
authors.forename: Michael
authors.initials: M
authors.lastname: Green
authors.forename: Caroline D
authors.initials: CD
authors.lastname: Rae
authors.forename: Lynne E
authors.initials: LE
authors.lastname: Bilston
mesh_terms: D000465:Algorithms; D000818:Animals; D016880:Anisotropy; D002417:Cattle; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004548:Elasticity; D054459:Elasticity Imaging Techniques / Q000379:methods*; D004867:Equipment Design; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015233:Models, Statistical; D018482:Muscle, Skeletal / Q000473:pathology; D019047:Phantoms, Imaging; D012212:Rheology; D013314:Stress, Mechanical; D014783:Viscosity