IEEE Trans Biomed Circuits Syst. 2018 Dec;12(6):1458-1466. doi: 10.1109/TBCAS.2018.2871498. Epub 2018 Sep 20.
With the increased commercial availability of high channel count MR coil arrays and the associated higher number of plugs in the patient bed, it has become a common practice to include switch matrices in the receive path of MR systems. These allow the arbitrary routing of a signal from any plug to any receiver in the console. While switch matrices are standard in systems at clinical field strength and have been developed for systems operating up to 4T, they have not yet been implemented at ultra-high field (UHF). Here, we present a switch matrix suitable for operation at UHF. Crossbar switches, which are the most frequently employed forms of a switch matrix, use RF switches to connect horizontal input lines with the desired vertical output line. This leaves transmission line stubs of variable length physically connected with the selected signal path, potentially resulting in elevated signal losses. While this can be tolerated at low frequencies, and only needs partial compensation at intermediate frequencies (4T), a full compensation is required at UHF. In this study, an RF crossbar switch, which uses switchable compensation elements in both horizontal and vertical transmission lines, was implemented for a 9.4T MRI scanner. The prototype developed was evaluated for single channel and multichannel receive performance and benchmarked against a fixed wire connection.
随着高通道数磁共振线圈阵列的商业可用性的增加，以及患者床上的插头数量的相应增加，在磁共振系统的接收路径中包含开关矩阵已经成为一种常见做法。这些矩阵允许任意将信号从任何一个插头路由到控制台中的任何一个接收器。虽然开关矩阵在临床场强的系统中是标准配置，并且已经开发用于 4T 及更高场强的系统，但它们尚未在超高场（UHF）中实现。在这里，我们提出了一种适用于 UHF 操作的开关矩阵。纵横开关是开关矩阵最常用的形式之一，它使用射频开关将水平输入线与所需的垂直输出线连接起来。这会在物理上留下具有可变长度的传输线短截线与选定的信号路径相连，从而导致信号损耗增加。虽然在低频下可以容忍这种情况，并且仅在中频（4T）时需要部分补偿，但在 UHF 时需要完全补偿。在这项研究中，为 9.4T MRI 扫描仪实现了一种使用水平和垂直传输线中可切换补偿元件的射频纵横开关。开发的原型进行了单通道和多通道接收性能评估，并与固定接线进行了基准测试。
