Investigation of modelling parameters for finite element analysis of MR elastography

Introduction Magnetic resonance elastography (MRE) utilizes mechanically induced shear waves to attain material property measurements of in vivo tissue. Finite element analysis (FEA) can be used to replicate the technique in silico to aid in the testing and development of the MRE post-processing software. This study aimed to investigate the influence of modelling parameters upon FEA of MRE. Methods A geometry consisting of a cylindrical insert embedded in a cuboid was created. The shear modulus of the background material was 3 kPa whilst the shear modulus of the insert was varied from 4 to 9 kPa. A harmonic load was applied to the upper surface of the cuboid whilst displacements upon other surfaces were fixed in a variety of directions. The interaction between the two regions of the model was also investigated in addition to element type used to create the mesh. Results Fixing displacements at the boundaries in all directions caused significant overestimation of the shear modulus whilst defining a frictional interaction between the two regions prevented wave propagation throughout the model. The use of linear tetrahedral elements also resulted in large overestimations. Discussion This study showed the dependence of FEA of MRE upon modelling parameters demonstrating the need for consistency within the literature as to which parameters are applied and emphasizing the requirement for further development of these parameters such that they are more reflective of real conditions.