Fig. 3.

Minimum global SAR and RF power requirements of the transmit arrays versus lift-off. The reported values are associated with the excitation of a uniform flip angle distribution on a transverse plane through the center of a homogeneous sphere. Results are compared for the belt-like (a) and symmetric (b) array design. An optimal coil lift-off that minimizes the RF power requirements while achieving the target excitation profile with minimum SAR was observed for both lift-off strategies. SAR and power requirement plots are normalized by the UISAR at the corresponding magnetic field strength. Power requirements were calculated by adding the coil conductor losses into the minimum global RF power deposition. Achieved excitation profile from the designed RF pulses is shown in C.