An MRI apparatus includes a magnetic resonance imaging (MRI) system having a magnet to impress a polarizing magnetic field, a plurality of gradient coils positioned about the bore of the magnet to impose a magnetic field gradient, and an RF transceiver system and an RF switch controlled by a pulse module to transmit RF pulses to an RF coil assembly and to acquire MR images, and a computer programmed to apply a plurality of RF pulses configured to control RF excitation by a transmit coil array such that a waveform shape of each of the plurality of RF pulses is based on optimizing a spatial spectrum.