Magnetic Resonance Wire Coil Losses Estimation with Finite-Difference Time-Domain Method

Radiofrequency (RF) coils are used to transmit and receive signals in magnetic resonance (MR) systems. Optimized RF coil design has to take into account strategies to maximize the coil performance by choosing coil sizes and geometry for achieving the best signal-to-noise ratio (SNR). In particular, coil conductor and radiative loss contributions strongly affect the SNR value, with the first mainly playing a role in low-field MR systems especially, while the second could be the dominant coil loss mechanism for high-frequency tuned coils. This paper investigates the accuracy of the finite-difference time-domain (FDTD) method for separately estimating coil conductor and radiative loss contributions. Comparison with finite element method (FEM) analysis and workbench measurements performed on a home-built coil prototype permitted us to validate the simulation results. Moreover, this research, jointly with literature data on sample-induced losses estimation, demonstrates that an FDTD-based solver permits providing an SNR model for coils with various and complicated geometries.