Three-dimensional MREIT simulator of static bioelectromagnetism and MRI

Purpose: Magnetic resonance electrical impedance tomography (MREIT) aims to produce high-resolution cross-sectional images of a conductivity distribution inside the human body. We perform conductivity image reconstructions based on a relation between the conductivity distribution and induced magnetic flux density distributions subject to externally injected currents. This induced magnetic flux density is measured in MREIT using an MRI scanner. To facilitate MREIT research, we need a numerical simulator including static bioelectromagnetism and MRI data collection process. In this paper, we describe the development of a three-dimensional MREIT simulator (MREITSim). Methods: We describe various features of MREITSim including geometry modeling, meshing, finite element modeling and numerical computations of magnetic flux density and k-space MR data. We demonstrate the underlying bioelectromagnetic phenomena and MR data collection process using phantom models of without and with anomaly. We illustrate effects of noise in MR data and echo time on magnetic flux density computations. Results: We demonstrate numerical computations of current density and magnetic flux density distributions for current injections orthogonal to z-direction, the direction of the main magnetic field of an MRI scanner. The k-space MREIT data generation procedure is illustrated using a phantom model with an insulating anomaly. Conclusions: The simulator functions as a virtual MREIT scanner and provides quantitative numerical results of intended experimental studies. We suggest the simulator as a basic research tool for future MREIT studies of its theory, algorithm, experimental techniques and pulse sequence design.