The present invention relates to a magnetic resonance imaging MRI system (100) for acquiring magnetic resonance data from a target volume in a subject (101), the magnetic resonance imaging system (100) comprising: a plurality of excitation means (201) for generating a slice-/or slab-selective spatial radio frequency RF excitation magnetic field targeting slice/slab spatial variations in the target volume, and a controller (219) coupled to the plurality of excitation means (201), wherein the controller (219) is adapted for: determining a power level required by the plurality of excitation means (201) for generating the slice-/or slab-selective spatial RF excitation magnetic field, decomposing the slice-/or slab-selective spatial RF excitation magnetic field into respective RF excitation constituents of the plurality of excitation means (201), controlling each of the plurality of excitation means (201) to simultaneously generate the respective RF excitation constituent, using the determined power level for acquiring the magnetic resonance data.