Novel inductive decoupling technique for flexible transceiver arrays of monolithic transmission line resonators

This article presents a novel inductive decoupling technique for form-fitting coil arrays of monolithic transmission line resonators, which target biomedical applications requiring high signal-to-noise ratio over a large field of view to image anatomical structures varying in size and shape from patient to patient.

Individual transmission line resonator elements are mutually decoupled using magnetic flux sharing by overlapping annexes. This decoupling technique was evaluated by electromagnetic simulations and bench measurements for two- and four-element arrays, comparing single- and double-gap transmission line resonator designs, combined either with a basic capacitive matching scheme or inductive pickup loop matching. The best performing array was used in 7T MRI experiments demonstrating its form-fitting ability and parallel imaging potential.

The inductively matched double-gap transmission line resonator array provided the best decoupling efficiency in simulations and bench measurements (<-15 dB). The decoupling and parallel imaging performance proved robust against mechanical deformation of the array.

The presented decoupling technique combines the robustness of conventional overlap decoupling regarding coil loading and operating frequency with the extended field of view of nonoverlapped coils. While demonstrated on four-element arrays, it can be easily expanded to fabricate readily decoupled form-fitting 2D arrays with an arbitrary number of elements in a single etching process.