Towards Accurate MRF T2 in Structured Material at 0.55T Using MT-suppressed Excitations

Purpose To develop a 0.55 T FISP-MRF approach that provides more accurate T2 maps in structured materials (e.g. white matter). Method Non-selective low-bandwidth excitation strategies that reduce on-resonance MT effects were implemented. Dictionaries were simulated using a conventional single pool model. Estimated MRF T2 maps using the non-selective approach with 2 pulse durations were compared against MRF T2 maps using the conventional slab-selective approach, and against conventional but slow reference measurements. Results The proposed approach substantially reduces T2 underestimation in white matter from ∼40 % to <10 % without compromising precision. Conclusion The use of non-selective low-bandwidth excitations substantially reduces MT effects in 0.55T FISP-MRF, enabling use of a single pool model. This is particularly important for MRF at low field strengths and in structured materials such as white matter.