Sung-Min Sohn1, Lance DelaBarre2, Anand Gopinath1, University of Minnesota University of Minnesota Vaughan, 12
1Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States; 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States
RF coils with transmission line elements are commonly used for high-field MRI, as both transmitter and transceiver elements. The RF coil element is typically terminated at the variable trimmer capacitors commonly called matching capacitor (Cm) and tuning capacitor (Ct) at one end, and a fixed value capacitor (Cf) at the other to form a capacitively tuned, matched, and shortened half-wave resonator. These resonant coil elements usually have a high quality factor (Q). High transmit efficiency and receiver signal-to-noise (SNR) are dependent on a well tuned (to Larmor frequency) and matched (to load) resonance for the element. Conversely, variable body loading of these coil elements can adversely impact both tuning and matching, and therefore efficiency and SNR of the coil. This study demonstrates a high-speed, electronically actuated, automatic impedance matching and tuning technique to assure optimal coil efficiency and SNR over a range of patient-coil loading conditions.