Evaluation of 8-Channel Radiative Antenna Arrays for Human Head Imaging at 10.5 Tesla

• Main Authors: Myung Kyun Woo, Lance DelaBarre, Matt Thomas Waks, Young Woo Park, Russell Luke Lagore, Steve Jungst, Yigitcan Eryaman, Se-Hong Oh, Kamil Ugurbil, Gregor Adriany
• Format: Article
• Language: English
• Published: MDPI AG 2021-09-01
• Series: Sensors
• Subjects: center-fed antenna; dipole antenna; end-fed antenna; monopole antenna; sleeve antenna; ultra-high field imaging
• Online Access: https://www.mdpi.com/1424-8220/21/18/6000

For human head magnetic resonance imaging at 10.5 tesla (T), we built an 8-channel transceiver dipole antenna array and evaluated the influence of coaxial feed cables. The influence of coaxial feed cables was evaluated in simulation and compared against a physically constructed array in terms of transmit magnetic field (B₁⁺) and specific absorption rate (SAR) efficiency. A substantial drop (23.1% in simulation and 20.7% in experiment) in B₁⁺ efficiency was observed with a tight coaxial feed cable setup. For the investigation of the feed location, the center-fed dipole antenna array was compared to two 8-channel end-fed arrays: monopole and sleeve antenna arrays. The simulation results with a phantom indicate that these arrays achieved ~24% higher SAR efficiency compared to the dipole antenna array. For a human head model, we observed 30.8% lower SAR efficiency with the 8-channel monopole antenna array compared to the phantom. Importantly, our simulation with the human model indicates that the sleeve antenna arrays can achieve 23.8% and 21% higher SAR efficiency compared to the dipole and monopole antenna arrays, respectively. Finally, we obtained high-resolution human cadaver images at 10.5 T with the 8-channel sleeve antenna array.