Zusammenfassung:
Low-field magnetic resonance imaging (MRI) is an attractive route toward affordable, mobile, and energy-efficient scanners, but its intrinsically reduced signal-to-noise ratio (SNR) places stringent requirements on radiofrequency (RF) coil efficiency and impedance matching. This work presents the design, electromagnetic numerical simulations, and experimental validation of a solenoidal RF coil that uses a simple mechanical impedance matching strategy based on a movable non-resonant inductive coupling loop. A 12-turn copper-tube solenoid was implemented in an open vertical-field magnet operating at 0.1 T without a Faraday cage and compared with a reference coil matched by a lumped L-shape network. Numerical simulations and experimental measurements show that translating the non-resonant loop along the solenoid axis strongly modulates the reflection coefficient S??, enabling fine control of the coupling between the 50 Ω transmit/receive chain and the resonant solenoid. At the optimal loop position, the mechanically matched configuration results in higher mean |H| and |B??| fields inside a uniform phantom compared to the conventional L-matched design, with similar field homogeneity. Phantom imaging and nutation experiments confirm that the loop position optimization improves RF efficiency and leads to increased mean SNR across slices, whereas the L-matched coil shows a higher signal but 30% higher noise and 47% broader linewidth. The proposed non-resonant inductive coupling therefore provides a low-cost, low-loss, and easily adjustable approach to impedance matching in low-field MRI, well suited to mobile point-of-care systems.
SWITCH edu-ID
Verwaltung
