Optically Controlled Switch-Mode Current-Source Amplifiers for On-Coil Implementation in High-Field Parallel Transmission
Optically Controlled Switch-Mode Current-Source Amplifiers for On-Coil Implementation in High-Field Parallel Transmission
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DOI：
10.1002/mrm.25857
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发表时间：
2016-07-01
影响因子：
3.3
通讯作者：
Duyn, Jeff H.
中科院分区：
文献类型：
--
作者：
Gudino, Natalia;Duan, Qi;Duyn, Jeff H.
目的：我们测试的可行性，实施并行传输（pTX）的高场MRI使用射频（RF）放大器的设计，位于或在附近的RF transmit coil.Method：我们设计了一个电流源开关模式放大器的基础上小型化，可编程电子。控制放大器的光学RF载波和包络信号通过定制接口从扫描仪控制中可访问的RF源获得。放大器性能通过台式测量以及7T（300 MHz）和11.7 T（500 MHz）下的成像进行测试。执行pTX的能力进行了评估，通过测量通道间耦合和相位调整在一个双通道setup.Results：放大器提供超过44 W的射频功率，并造成最小的干扰与MRI。该接口可获得精确的光控制信号，载波频率范围为64至750 MHz。去耦优于14分贝之间获得两个线圈环路之间的分离只有1厘米。通过在7 T和11.7 T下获取无伪影图像来证明其在MRI中的应用。结论：我们提出了一种用于高场在线实施的光学控制小型化RF放大器，这应该有助于高密度pTX阵列的实施。2015年出版。本条目属于美国政府作品，在美国属于公有领域。
Purpose: We tested the feasibility of implementing parallel transmission (pTX) for high-field MRI using a radiofrequency (RF) amplifier design to be located on or in the immediate vicinity of an RF transmit coil.Method: We designed a current-source switch-mode amplifier based on miniaturized, nonmagnetic electronics. Optical RF carrier and envelope signals to control the amplifier were derived, through a custom-built interface, from the RF source accessible in the scanner control. Amplifier performance was tested by benchtop measurements as well as with imaging at 7T (300 MHz) and 11.7 T (500 MHz). The ability to perform pTX was evaluated by measuring interchannel coupling and phase adjustment in a two-channel setup.Results: The amplifier delivered in excess of 44 W RF power and caused minimal interference with MRI. The interface derived accurate optical control signals with carrier frequencies ranging from 64 to 750 MHz. Decoupling better than 14 dB was obtained between two coil loops separated by only 1 cm. Application to MRI was demonstrated by acquiring artifact-free images at 7 T and 11.7 T.Conclusion: We propose an optically controlled miniaturized RF amplifier for on-coil implementation at high fields that should facilitate implementation of high-density pTX arrays. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.