Investig Magn Reson Imaging.  2026 Mar;30(1):38-46. 10.13104/imri.2025.0060.

Comparative Analysis of Multiple Combined Structure Transmit Arrays for 10.5 Tesla Human Brain Imaging

• Park YD
• Kwak JM
• Woo MK

• KMID: 2579152
• DOI: http://doi.org/10.13104/imri.2025.0060

Abstract

Purpose
To evaluate several hybrid multi-element configurations to enhance B₁⁺ effi- ciency, 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.

Keyword

Dipole antenna; Hybrid antenna; Monopole antenna; RF coil; Ultra-high field magnetic resonance imaging