Purpose: To evaluate several hybrid multi-element configurations to enhance B1 + efficiency, defined as the transmit magnetic field generated by the radiofrequency (RF) coil normalized by the net input power, and spatial coverage for 10.5 tesla (T) human brain imaging.Materials and Methods: Finite-difference time-domain simulations were performed using an anatomically detailed human head model to assess circularly polarized B1 + fields generated by 8-channel loop, dipole antenna, and monopole and dipole hybrid antenna (MDH) arrays.These baseline designs were extended to 16-channel arrays combining loops with dipole antennas or MDHs and to interleaved MDH-based arrays incorporating axially displaced dipole or monopole antennas.Results: The 8-channel MDH array yielded the highest central B1 + efficiency, exceeding loop and dipole antenna arrays by 38.5% and 33.3%, respectively, but peripheral coverage remained limited.The 16-channel loop + dipole antenna and loop + MDH arrays improved overall B1 + efficiency by up to 28.9% relative to their 8-channel counterparts.Interleaved combined structure arrays further enhanced peripheral excitation and superior-inferior coverage, with the T-shaped monopole antenna + MDH configuration achieving a high central efficiency.Conclusion: MDH-centered combined structure arrays effectively balance deep-field efficiency and peripheral coverage at 10.5 T. Interleaving monopole antenna-type elements beneath MDHs provides additional improvement and represents a promising design pathway for achieving more uniform excitation in 10.5 T brain imaging.
Park et al. (2026) studied this question.