Passive RF shimming with fractal metasurfaces in a 7T head coil

B₁⁺ inhomogeneities in the temporal lobes of the brain are common while using a birdcage coil at 7T. Different passive RF shimming approaches have already targeted this problem, at the cost of decreasing the B₁⁺ field in other important areas or being uncomfortable to the patient. Here, we present a new approach based on two resonant fractal metasurfaces printed on ultra-thin flexible substrate. We show that these resonators improve the B₁⁺ field amplitude simultaneously in each temporal lobe without affecting the B₁⁺ field amplitude in other parts of the brain.