Dual-Tuned Removable Common-Mode Current Trap for Magnetic Resonance Imaging and Spectroscopy

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are preferred methods of gathering structural and metabolic information from the body due to their non-invasive approach to obtaining a diagnosis. Dual-tuned radiofrequency (RF) coils can detect signals produced by both hydrogen and a second atomic nuclei of interest. However, undesired electromagnetic coupling often confounds both the design and utilization of RF coils. Coaxial shield currents, also known as common-mode currents, can be induced during MR scans and cause image distortion and reduction in signal-to-noise ratio (SNR); furthermore, the energy dissipated from the cabling can create heat that poses a risk of patient burns if the routed too closely. Thus, common-mode currents must be suppressed in RF coils by employing non-magnetic current traps. In this paper, we present a novel dual-tuned current trap that is fully removable and does not require soldering directly to the cable. The design was manufactured with 3D printing to support rapid fabrication and distribution. Bench measurements at the 3T Larmor frequencies for hydrogen and phosphorous-31 demonstrate common-mode attenuation of –18 dB and –8.4 dB respectively.