System and method for reducing specific absorption rate in magnetization transfer magnetic resonance imaging

A magnetic resonance imaging (MM) system, comprising:

• a magnet system configured to generate a polarizing magnetic field about at least a portion of a subject arranged in the MRI system;
• a plurality of gradient coils configured to apply at least one magnetic gradient field to the polarizing magnetic field;
• a radio frequency (RF) system including a multichannel RF coil array configured to apply an RF field to the subject and to receive magnetic resonance signals therefrom;
• a computer system programmed to:
• select a plurality of resonance frequencies associated with a population of spins having a broad resonance frequency spectrum;
• provide an RF transmission profile for each of a plurality of transmit channels associated with the multichannel RF coil array;
• select a set of compressed specific absorption rate (SAR) matrices at which SAR can be evaluated;
• design a plurality of RF pulses for achieving a desired magnetization transfer effect by determining a set of RF waveforms that maximize power deposition to the population of spins while minimizing an average local SAR of the plurality of RF pulses evaluated at the compressed SAR matrices, wherein the power deposition to the population of spins is determined based on the selected plurality of resonance frequencies and the RF transmission profiles;
• and
• direct the RF system to produce the plurality of RF pulses using the determined set of RF waveforms, such that a desired saturation effect is generated in the population of spins.