A high duty-cycle, multi-channel, power amplifier for high-resolution radiofrequency encoded magnetic resonance imaging

Abstract

ObjectiveA 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 methodsA dual-channel RF power amplifier dedicated for TRASE at 0.22\xa0T (9.27\xa0MHz) was designed and constructed using commercially available components. The amplifier was tested on the bench and used a 0.22\xa0T MRI system with a twisted solenoid and saddle RF coil combination capable of a single-axis TRASE.ResultsThe amplifier is capable of sequential, dual-channel operation up to 50% duty cycle, 1\xa0kW peak output and highly stable 100\xa0μs RF pulse trains. High spatial resolution one-dimensional TRASE was obtained with the power amplifier to demonstrate its capability.ConclusionThe 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.