Implementation of a Four-channel Phased-array Coil for Patloc Imaging

Introduction: Non-linear local gradients have been introduced for high-magnetic fields to alleviate problems arising from fast gradient switching and resulting peripheral nerve stimulation [1]. This work is focused on the implementation of a selfconstructed four-channel phased-array coil for multi-parallel PatLoc imaging to study the non-linear geometry of these fields under realistic conditions. (PatLoc = parallel imaging technique using localized gradients). Methods: PatLoc gradients are most effective in close proximity to their coil wires. For that reason, radio frequency coils located inside of these gradient coils should be as thin as possible to avoid unnecessary reduction of the available volume of interest. For multi-parallel reception, a four-channel receive array coil with a very thin wall has been created [2]. In combination with a volume resonator such a setup allows the investigation of samples inside of non-linear Patloc fields. Thus, a self-built saddle-coil resonator and, for comparison, a commercial Bruker linear resonator have been tested in that arrangement. Figure 1 shows a sketch of the arrangement of the coils inside the bore of a 9.4 T magnet.