IEEE Trans Med Imaging. 2020 Apr;39(4):1085-1093. doi: 10.1109/TMI.2019.2942194. Epub 2019 Sep 18.
A capacitive impedance metasurface combined with a transceiver coil to improve the radio frequency magnetic field for 1.5T magnetic resonance imaging applications is presented. The novel transceiver provides localized enhancement in magnetic flux density when compared to a transceiver coil alone by incorporating an electrically small metasurface using an interdigital capacitance approach. Full field simulations employing the metasurface show a significant improvement in magnetic flux density inside a homogeneous dielectric phantom, which is also shown to perform well for a range of depths into the phantom. The concept was experimentally demonstrated through vector network analyzer measurements and images have been taken using a 1.5T MRI scanner. The results show there is a 216% improvement in transmission efficiency, a 133% improvement in receiver signal-to-noise-ratio (SNR), and a 415% improvement in transceiver SNR for a particular transmission power when compared against a surface coil positioned at the same distance from the phantom, where these improvements are the maximum observed during experiments.
提出了一种电容式阻抗超表面与收发线圈相结合的方法，用于提高 1.5T 磁共振成像应用中的射频磁场。与单独使用收发线圈相比，新型收发器通过采用叉指电容方法使用小型电超表面，提供了局部磁通密度增强。采用超表面的全场模拟显示，在均匀介电体幻像内的磁通密度有显著提高，在幻像内的一定深度范围内也表现良好。该概念通过矢量网络分析仪测量进行了实验验证，并使用 1.5T MRI 扫描仪拍摄了图像。结果表明，与放置在与幻像相同距离的表面线圈相比，在特定传输功率下，传输效率提高了 216%，接收器信噪比 (SNR) 提高了 133%，收发器 SNR 提高了 415%，这些改进是实验中观察到的最大值。
