Experimental verification of enhanced B1 Shim performance with a Z-encoding RF coil array at 7 tesla.

Introduction: In recent years the field has made remarkable progress addressing a number of difficult RF related issues that arise at 7 tesla and above [1-4]. However, homogeneous whole head coverage and spin excitation in areas of the lower temporal lobe and the cerebellum is still difficult to achieve at 7 tesla. Previously a 32 channel transceiver array coil design [5] based on short strip line transceiver elements was presented that addressed this problem by allowing for B1 manipulation along the zdirection. Here we describe a modification of such a coil that supports visual task presentation within the spatial constrains of a narrow head gradient coil. To verify the enhanced B1 shim performance of this z -shim array we compared the latter coil with a standard 16 channel stripline array with matching spatial coverage.