Volume coil for MRI based on metasurface

International audienceConventional birdcages are radiofrequency coils for magnetic resonance imaging (MRI) that consists of closed, right-hand or left-hand transmission lines with sub-wavelength periodicity. Analyzing these coils in terms of metasurface leads to engineering their properties as will and achieve original applications. To that end, we control the intrinsic impedance and the phase shift of each unit cell. As a demonstration, we use this concept to break the periodicity of the structure in order to provide a wide aperture allowing an easy access to the region of interest. We show that this coil, that we have called opencage, achieves good isolation between two driving ports and high homogeneity of the magnetic field. The results of measurements realized with phantom and in-vivo in MRI are presented. These results have confirmed the good performances predicted by our theoretical approach and the numerical calculations. This opencage coil could be used for many applications such as pre-clinical imaging of small animals or human head clinical imaging