用于超高场全身磁共振成像的高功率高隔离发射/接收开关。

摘要(中文译文)

在磁共振成像（MRI）系统中，具有高隔离度的射频（RF）发射/接收（T/R）开关在管理发射机与接收机之间射频信号流动方面起着至关重要的作用。对于超高场（UHF）MRI系统，高功率器件中寄生参数的影响日益显著，导致采用50欧姆λ/4传输线的传统T/R开关发生频率偏移，进而导致目标频率处隔离度恶化。这将增加发射模式下接收电路损坏的风险以及接收模式下的射频干扰，从而降低图像信噪比（SNR）并导致图像伪影。本研究提出了一种适用于5 T全身MRI在高频高功率条件下工作的新型谐振电路T/R开关。结果表明，该新型T/R开关具有8 kW的高功率处理能力，在发射模式下可提供38.8 dB的高隔离度，在接收模式下可提供46.2 dB的隔离度，而传统T/R开关在目标频率处发射模式下仅提供19.0 dB的隔离度，接收模式下仅提供23.6 dB的隔离度。最重要的是，该新型T/R开关能够减少图像伪影和插入损耗。因此，使用该新型T/R开关实现了信噪比提升15.7%的更高SNR。这些结果表明，所提出的T/R开关可应用于超高场全身MRI，在高功率发射中具有可靠性和安全性。

Abstract

The radio frequency (RF) transmit/receive (T/R) switch with high isolation in magnetic resonance imaging (MRI) systems plays a crucial role in managing the flow of RF signals between the transmitter and the receiver. For ultra-high field (UHF) MRI systems, the impact of parasitic parameters in high-power devices becomes increasingly significant, leading to the frequency shift of the traditional T/R switch using 50 Ohms λ/4 transmission lines, which in turn leads to a deterioration in isolation at the target frequency. This will increase the risk of receiving circuit damage in the transmit mode and RF interference in the receive mode, thereby degrading image signal-to-noise ratio (SNR) and resulting in image artifacts. In this study, a T/R switch with a novel resonant circuit was proposed for 5 T whole-body MRI under high-frequency and high-power conditions. As a result, the novel T/R switch with a high power capability of 8 kW can provide a high isolation of 38.8 dB in the transmit mode and an isolation of 46.2 dB in the receive mode, while the traditional T/R switch provided an isolation of 19.0 dB in the transmit mode and an isolation of 23.6 dB in the receive mode at the target frequency. Most importantly, the novel T/R switch can reduce image artifacts and insertion loss. As a result, higher SNR with an improvement of 15.7% has been achieved using the novel T/R switches. These results demonstrate that the proposed T/R switch can be applied in UHF whole-body MRI with reliability and safety in high-power transmission.

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