Design of Distributed Spiral Resonators for the Decoupling of MRI Array Coils

This paper describes a distributed filter layout for the decoupling of 7T Radio Frequency (RF) Magnetic Resonance Imaging (MRI) 1H planar array coils based on miniaturized spiral resonators as unit-cells. The spirals, opportunely designed in terms of resonant frequency and with an optimized layout to minimize their number, are placed on the same dielectric substrate of the RF coils. We demonstrated through numerical simulations the decoupling effectiveness of the distributed filter, observing a decoupling greater than -20 dB and satisfying matching levels (-30 dB) for the RF coils. The possibility to print on the same substrate both the coils and the filter results in practical advantages like excellent mechanical robustness and less sensibility to potential fabrication tolerances.