Potential of Patch Antennas as MRI Scanner Bore-Integrated Transmit Arrays for 7 T Head Imaging

Patch antennas have been recently proposed as scanner integrated transmit coils for 7 T magnetic resonance body imaging. However, state of the art head imaging is performed with smaller head specific gradients. This study proposes a capacitively shorted patch antenna and shows its potential in an eight-channel array for 7 T head imaging using local head gradient coils and compares it to stripline and loop arrays. It was shown, that the concept of capacitor shorted patch antennas worked in simulations and measurements. In the eight-channel array, the patch antenna had the highest coupling between elements compared to stripline and loop arrays and using the circular polarized mode 40% higher and 33% lower Tx efficiency, respectively. The SAR efficiency was highest among the compared element types. In this mode, in the central, transversal slice, its homogeneity was comparable to the stripline elements and within the whole head slightly superior.