A Comparison of Ansoft HFSS and CST Microwave Studio Simulation Software for Multi-channel Coil Design and SAR Estimation at 7 T MRI

We present a comparison of RF simulations with Ansoft HFSS and CST Microwave studio software, for a commercially available 7 T multi-channel coil. We investigated the conditions influencing precision and simulation time. When simulation parameters (such as mesh size) are appropriately selected and full coverage of the results is ensured, there is agreement between simulated and experimentally determined S parameters, between simulated and actual capacitor values, and between simulated and measured RF field. At this point, both simulation methods then provide comparable results, to within 15%. In their current implementations, the Ansoft HFSS frequency domain solver converges much faster than the CST time domain solver. HFSS based RF circuit and 3-D EM fields co-simulation significantly speeds up MRI coil design, because the simulation time no longer depends strongly on simulated port numbers and the length of the smallest mesh cell.