Modeling for Electromagnetic Characterization, Prediction, and Reconstruction

Electromagnetic modeling is an essential and crucial element in MRI-based methods of characterizing electromagnetic properties or current flow. In its simplest form, modeling can be used to predict measurements of magnetic flux density (B_z in the case of MREIT or B₁ fields in the case of EPT) based on realistic representations of the imaged object. Further, projected current density methods must refer to a uniform model of an imaged object in order to calculate the projected current density distribution. Modeling in this area is most commonly performed using finite element methods and often using commercial finite element software. While it is not necessary to know every feature of this type of software, understanding the basics of finite element methods will help in interpreting and examining the results and learning how to perform simulations efficiently. We describe aspects of the finite element approach and demonstrate models relevant to simulations performed in this area.