Feasibility of MR fingerprinting using a high-performance 0.55 T MRI system

Background: MR fingerprinting (MRF) is a versatile method for rapid multi-parametric quantification. The application of MRF for lower MRI field could enable multi-contrast imaging and improve exam efficiency on these systems. The purpose of this work is to demonstrate the feasibility of 3D whole-brain T1 and T2 mapping using MR fingerprinting on a contemporary 0.55 T MRI system. Materials and methods: A 3D whole brain stack-of-spirals FISP MRF sequence was implemented for 0.55 T. Quantification was validated using the NIST/ISMRM Quantitative MRI phantom, and T1 and T2 values of white matter, gray matter, and cerebrospinal fluid were measured in 19 healthy subjects. To assess MRF performance in the lower SNR regime of 0.55 T, measurement precision was calculated from 100 simulated pseudo-replicas of in vivo data and within-session measurement repeatability was evaluated. Results: T1 and T2 values calculated by MRF were strongly correlated to standard measurements in the ISMRM/ NIST MRI system phantom (R2 > 0.99), with a small constant bias of approximately 5 ms in T2 values. 3D stackof-spirals MRF was successfully applied for whole brain quantitative T1 and T2 at 0.55 T, with spatial resolution of 1.2 mm & times; 1.2 mm & times; 5 mm, and acquisition time of 8.5 min. Moreover, the T1 and T2 quantifications had precision <5%, despite the lower SNR of 0.55 T. Conclusion: A 3D whole-brain stack-of-spirals FISP MRF sequence is feasible for T1 and T2 mapping at 0.55 T.

Automated summary

The study demonstrated the feasibility of whole-brain T1 and T2 mapping using MR fingerprinting on a 0.55 T MRI system, with validated accuracy and repeatability despite lower signal-to-noise ratio. The method was successful for quantitative imaging even in lower magnetic field strengths.