A medical imaging system (2) excites multiple nuclei through a single RF amplifier (24). The medical imaging system (2) includes a magnet (10) that generates a main magnetic field (Bo) in an examination region. A gradient coil (14) superimposes magnetic field gradients (G) on the main magnetic field Bo. At least one transmitter (28) generates multi-nuclei excitation pulses associated with at least two different isotopes and two different frequency spectra. The single amplifier (24) sends the multi-nuclei excitation pulses to a RF coil (18, 20) for application to the examination region.