A Passive and Conformal Magnetic Metasurface for 3T MRI Birdcage Coil

In this paper, a passive and conformal magnetic metasurface excited by a 3T-MRI birdcage coil and able to enhance the magnetic field distribution inside the biological load is presented. The proposed structure is composed by a 5 × 13 passive array, whose unit-cells are loaded with capacitors chosen to precisely control the induced currents. These reactive loads are calculated with an analytic algorithm that optimizes the magnetic field distribution. We performed full-wave simulations of a biologically loaded birdcage coil working at 128 MHz with and without the metasurface presence. Specifically, the two cases were compared in terms of $B_{1}{}^{+}$ distribution inside the phantom. A significant magnetic field enhancement in the phantom region closer to the metasurface was observed, proportionally improving the signal-to-noise ratio. Our preliminary results suggest the possibility to adopt conformal metasurfaces for improving transmit performance in 3T magnetic resonance imaging, which will be further explored in future work.