Department of Nanophotonics and Metamaterials, ITMO University, Saint Petersburg, Russian Federation.
Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands.
Magn Reson Med. 2018 Oct;80(4):1726-1737. doi: 10.1002/mrm.27140. Epub 2018 Feb 9.
Design and characterization of a new inductively driven wireless coil (WLC) for wrist imaging at 1.5 T with high homogeneity operating due to focusing the B field of a birdcage body coil.
The WLC design has been proposed based on a volumetric self-resonant periodic structure of inductively coupled split-loop resonators with structural capacitance. The WLC was optimized and studied regarding radiofrequency fields and interaction to the birdcage coil (BC) by electromagnetic simulations. The manufactured WLC was characterized by on-bench measurements and in vivo and phantom study in comparison to a standard cable-connected receive-only coil.
The WLC placed into BC gave the measured B1+ increase of the latter by 8.6 times for the same accepted power. The phantom and in vivo wrist imaging showed that the BC in receiving with the WLC inside reached equal or higher signal-to-noise ratio than the conventional clinical setup comprising the transmit-only BC and a commercial receive-only flex-coil and created no artifacts. Simulations and on-bench measurements proved safety in terms of specific absorption rate and reflected transmit power.
The results showed that the proposed WLC could be an alternative to standard cable-connected receive coils in clinical magnetic resonance imaging. As an example, with no cable connection, the WLC allowed wrist imaging on a 1.5 T clinical machine using a full-body BC for transmitting and receive with the desired signal-to-noise ratio, image quality, and safety.
设计并描述一种新的感应式无线线圈（WLC），用于在 1.5 T 下进行腕部成像，其具有高度均一的特性，这得益于对鸟笼体线圈的 B 场进行聚焦。
该 WLC 的设计基于电感耦合分裂环谐振器的体积自谐振周期性结构，并具有结构电容。通过电磁模拟对 WLC 的射频场和与鸟笼线圈（BC）的相互作用进行了优化和研究。通过台架测量以及与标准电缆连接的仅接收线圈的体内和仿体研究对制造的 WLC 进行了特性描述。
将 WLC 置于 BC 中，在相同的可接受功率下，后者的测量 B1+增加了 8.6 倍。BC 与 WLC 一起进行的腕部仿体和体内成像显示，与传统的临床设置（包括仅发射的 BC 和商用仅接收的 Flex 线圈）相比，接收时的 BC 达到了相等或更高的信噪比，并创建了没有伪影。模拟和台架测量证明了在特定吸收率和反射发射功率方面的安全性。
结果表明，所提出的 WLC 可以作为临床磁共振成像中标准电缆连接的接收线圈的替代方案。例如，在没有电缆连接的情况下，WLC 允许在 1.5 T 临床机器上使用全身体线圈进行腕部成像，以获得所需的信噪比、图像质量和安全性。
