Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN 55455, USA.
Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea.
Sensors (Basel). 2021 Sep 8;21(18):6000. doi: 10.3390/s21186000.
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 (B) and specific absorption rate (SAR) efficiency. A substantial drop (23.1% in simulation and 20.7% in experiment) in B 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.
针对 10.5T 人体头部磁共振成像，我们构建了一个 8 通道收发偶极子天线阵列，并评估了同轴线馈线的影响。我们在模拟中评估了同轴线馈线的影响，并将其与物理构建的阵列在发射磁场 (B) 和比吸收率 (SAR) 效率方面进行了比较。在紧密的同轴线馈线设置下，B 效率显著下降（模拟中下降 23.1%，实验中下降 20.7%）。为了研究馈电位置，我们将中心馈电偶极子天线阵列与两个 8 通道端馈阵列：单极天线和套管天线阵列进行了比较。使用仿体的模拟结果表明，与偶极子天线阵列相比，这些阵列的 SAR 效率提高了约 24%。对于人体头部模型，我们观察到 8 通道单极天线阵列的 SAR 效率比仿体低 30.8%。重要的是，我们对人体模型的模拟表明，套管天线阵列与偶极子和单极天线阵列相比，SAR 效率分别提高了 23.8%和 21%。最后，我们使用 8 通道套管天线阵列在 10.5T 下获得了高分辨率的人体尸体图像。
