Comparison of Time and Frequency Domain Solvers for Magnetic Resonance Coils at Different Field Strengths Using a Single Computational Platform

Rapid prototyping and safety assessments are essential in the modern development of radio frequency coils for magnetic resonance imaging. The use of 3D electromagnetic simulations can avoid expensive physical coil prototyping while providing quantities to determine local patient safety which is not measurable in vivo. Currently, 3D electromagnetic simulations are mostly solved on variations of two solver types, namely the time domain and the frequency domain solver. In this work, we compared these solvers and tested key simulation parameters using a single computational platform with state-of-the-art computational methods and computational human models. Our analysis included computational cost, B$_1^+$-field and power loss density for a range of common radio frequency setups used at different Larmor frequencies (field strengths, respectively) in magnetic resonance imaging systems. We found that a coarse mesh in a time solver has large unpredictable focal errors ($>$50%) due to partial volume artifacts while the frequency solver showed more linearity in the errors when reducing computational cost which could allow for more efficient simulations with reduced safety concerns. We expect our work to provide further insights into parameter and solver selection and contribute towards standardization in coil simulation in magnetic resonance imaging.