3D magnetic resonance fingerprinting with quadratic RF phase
Rasim Boyacıoğlu, Charlie Wang, Dan Ma, Debra McGivney, Xin Yu, Mark A. Griswold
Abstract
Purpose To implement 3D magnetic resonance fingerprinting (MRF) with quadratic RF phase (qRF‐MRF) for simultaneous quantification of T 1 , T 2 , ΔB 0 , and . 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 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 contrast and ΔB 0 . The precision of 3D qRF‐MRF was 1.5‐2 times higher than routine clinical scans. 3D qRF‐MRF ΔB 0 maps were further processed to highlight the susceptibility contrast. Conclusion Natively co‐registered 3D whole brain T 1 , T 2 , , ΔB 0 , and QSM maps can be acquired in as short as 5 min with 3D qRF‐MRF.