Capacitors Quality Effect in Magnetic Resonance Radiofrequency Coils

Radiofrequency (RF) coils are key components in magnetic resonance (MR) systems since the use of coils which fit around parts of the body to be imaged is necessary for obtaining high-quality images. As a first approximation, an RF coil is essentially a tuned electrical circuit that comprises an inductor and a capacitor, which may be adjusted to make the resonant frequency the desired Larmor frequency. Capacitor losses can drastically reduce RF coil overall performances. This work reviews literature describing how the choice of the capacitors quality affects the coil overall performance. Moreover, experiments with a loop-conductor coil were performed comparing low and high-quality capacitors with benchtop tests at high and low frequencies, and an imaging test was performed with a 1.5 T MR clinical scanner.