3D magnetic resonance fingerprinting with quadratic RF phase

Purpose To implement 3D magnetic resonance fingerprinting (MRF) with quadratic RF phase (qRF-MRF) for simultaneous quantification of T-1, T-2, Delta B-0, and T2*. Methods 3D MRF data with effective undersampling factor of 3 in the slice direction were acquired with quadratic RF phase patterns for T-1, T-2, and T2* sensitivity. Quadratic RF phase encodes the off-resonance by modulating the on-resonance frequency linearly in time. Transition to 3D brings practical limitations for reconstruction and dictionary matching because of increased data and dictionary sizes. Randomized singular value decomposition (rSVD)-based compression in time and reduction in dictionary size with a quadratic interpolation method are combined to be able to process prohibitively large data sets in feasible reconstruction and matching times. Results Accuracy of 3D qRF-MRF maps in various resolutions and orientations are compared to 3D fast imaging with steady-state precession (FISP) for T-1 and T-2 contrast and to 2D qRF-MRF for T2* contrast and Delta B-0. The precision of 3D qRF-MRF was 1.5-2 times higher than routine clinical scans. 3D qRF-MRF Delta B-0 maps were further processed to highlight the susceptibility contrast. Conclusion Natively co-registered 3D whole brain T-1, T-2, T2*, Delta B-0, and QSM maps can be acquired in as short as 5 min with 3D qRF-MRF.

Automated summary

The study introduced 3D magnetic resonance fingerprinting (MRF) with quadratic RF phase (qRF-MRF) for simultaneous quantification of T1, T2, Delta B0, and T2*. The combination of randomized singular value decomposition (rSVD) and quadratic interpolation method allowed for feasible processing of prohibitively large data sets.