Optimization of geometry for a dual-row MRI array at 400 MHz

We numerically investigated several magnetic resonance imaging radiofrequency transmit coil arrays, with and without a local shield, and with a range of scanner bore configurations. The latter had a significant influence on safety excitation efficiency. It is therefore important to include the scanner magnet room in the simulation domain, when the scanner bore is not isolated from the rest of the scan room by an electric shield or RF absorber. All arrays investigated provided similar inhomogeneity over the entire brain for a given excitation condition. However, for CP excitation mode transmit excitation efficiency was found to be higher for an array without a local shield.