Anisotropic stiffness of ex vivo swine heart estimated by transversely isotropic nonlinear inversion MRE at 2mm isotropic voxel resolution

MR elastography (MRE) must account for the anisotropic nature of myocardial tissue to accurately quantify stiffness. The constitutive matrix for this material was rotated to align with the fibers. One ex vivo swine heart was scanned with DTI and MRE sequences at 2 isotropic voxel resolution. Transversely isotropic viscoelastic stiffness was reconstructed using the Non-Linear Inversion (NLI) algorithm. Elastic properties (shear and Young’s modulus, tensile and shear anisotropy) were segment dependent, in agreement with the myocyte sheetlet formation, which varies in size and spacing according to the myocardial segment. Similarities between MRE and DTI metrics could be observed.