An Improved Quasi-static Finite-difference Scheme for Induced Field Evaluation in MRI based on the Biconjugate Gradient Method

In modern magnetic resonance imaging (MRI), there are concerns for the health and safety of patients and workers repeatedly exposed to magnetic fields, and therefore accurate and efficient evaluation of in situ electromagnetic field (EMF) distributions has gained a lot of significance. This paper presents a Biconjugate Gradient Method (BiCG) to efficiently implement the quasi-static finite-difference scheme (QSFD), which has been widely utilized to model and analyze magnetically induced electric fields and currents within the human body during the operation of the MRI systems and in other settings. The proposed BiCG method shows computational advantages over the iterative, successive over-relaxation (SOR) algorithm. The scheme has been validated against other known solutions on a lossy, multilayered ellipsoid phantom excited by an ideal loop coil. Numerical results on a 3D human body model demonstrate that the convergence time and memory consumption is significantly reduced using the BiCG method.