Objective

A radiofrequency (RF) power amplifier is an essential component of any magnetic resonance imaging (MRI) system. Unfortunately, no commercial amplifier exists to fulfill the needs of the transmit array spatial encoding (TRASE) MRI technique, requiring high duty cycle, high RF output power and independently controlled multi-channel capability. Thus, an RF amplifier for TRASE MRI is needed.

Materials and methods

A dual-channel RF power amplifier dedicated for TRASE at 0.22 T (9.27 MHz) was designed and constructed using commercially available components. The amplifier was tested on the bench and used a 0.22 T MRI system with a twisted solenoid and saddle RF coil combination capable of a single-axis TRASE.

Results

The amplifier is capable of sequential, dual-channel operation up to 50% duty cycle, 1 kW peak output and highly stable 100 μs RF pulse trains. High spatial resolution one-dimensional TRASE was obtained with the power amplifier to demonstrate its capability.

Conclusion

The constructed amplifier is the first prototype that meets the requirements of TRASE rectifying limitations of duty cycle and timing presented by commercial RF amplifiers. The amplifier makes possible future high resolution in vivo TRASE MRI.

中文翻译：

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高占空比，多通道功率放大器，用于高分辨率射频编码磁共振成像

客观的

射频（RF）功率放大器是任何磁共振成像（MRI）系统的重要组成部分。不幸的是，不存在商用放大器来满足发射阵列空间编码（TRASE）MRI技术的需要，该技术需要高占空比，高RF输出功率和独立控制的多通道功能。因此，需要用于TRASE MRI的RF放大器。

材料和方法

使用市售组件设计和构造了专用于TRASE的0.22 T（9.27 MHz）的双通道RF功率放大器。该放大器在工作台上进行了测试，并使用了0.22 T MRI系统，该系统具有能够实现单轴TRASE的扭曲螺线管和鞍形RF线圈组合。

结果

该放大器能够在高达50％的占空比，1 kW峰值输出和高度稳定的100μsRF脉冲序列的情况下连续双通道工作。利用功率放大器获得了高空间分辨率的一维TRASE，以证明其功能。

结论

所构建的放大器是第一个满足TRASE整流要求的商用原型，该限制限制了商用RF放大器对占空比和时序的限制。该放大器使将来的体内TRASE MRI高分辨率成为可能。