Multi-mode metasurface as a platform for the design of MRI coils and pads

In this work, we demonstrate the feasibility of a metasurface aimed to improve MRI performance at 3 T. Specifically, the metasurface can be used in two regimes and work as a passive radiofrequency (RF)-shimming pad or as an active multi-channel receive coil. The structure consists of a grid of metal strips loaded with capacitors. Placed under the patient inside a standard MRI scanner, the passive structure improves the homogeneity of the RF magnetic field and transmit efficiency similar to a conventional dielectric pad. Moreover operating in an active multi-mode regime, the metasurface has a penetration depth comparable to that of conventional decoupled loop coils of the same dimensions while providing a 1.75 times higher magnitude of the received magnetic field.