Three-Channel Modular Transmit Array for RF Gradient MRI: Enabling Low-Cost, Scalable RF Arrays Through Active Decoupling

Motivation: In order to realize the elimination of expensive B0 gradient hardware, new low-field imaging techniques demand a hardware redesign. Goal(s): Build a compact and modular RF transmit system at a low price point, in order to enable the expansion of RF gradient imaging systems. Approach: A previous design allowing for efficient and wireless operation of RF transmit in-field is modified with active channel decoupling to ease array expansion. Results: A three channel array of low-cost transmitters with distributed synthesis capabilities and closed-loop amplitude control for active decoupling is presented, with a build cost under US$150 per channel. Impact: Enabling high RF transmit channel count is essential for RF encoded imaging techniques like Selective Excitation through Nutation and Fingerprinting (SENF). Novel transmit system architecture presented here enables a reduction in system cost and easier array scaling while increasing portability.