Timo Liimatainen1, Silvia Mangia2, Andrew E. Tyan2, Hanne Hakkarainen1, Djaudat Idiyatullin2, Dennis Sorce2, Michael Garwood2, Shalom Michaeli2
1A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland; 2Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States
Series of amplitude and frequency modulation functions were designed using frequency swept pulses based on sine and cosine amplitude and frequency modulations to allow generation of MRI tissue contrast in the rotating frames of rank 1 ≤ n ≤ 5. The method is an extension of previously introduced technique RAFF (Relaxations Along a Fictitious Field), where the fictitious fields generated during non-adiabatic rotation lead to a locking magnetic field. The current method provides reduced SAR as compared to conventional and adiabatic rotating frame methods, and generates locking magnetic fields with much greater amplitudes than the maximum power of the pulses.