Simultaneous T-1, T-2, and T-1 rho cardiac magnetic resonance fingerprinting for contrast agent-free myocardial tissue characterization

Purpose: To develop a simultaneous T-1, T-2, and T-1 rho cardiac magnetic resonance fingerprinting (MRF) approach to enable comprehensive contrast agent-free myocardial tissue characterization in a single breath-hold scan. Methods: A 2D gradient-echo electrocardiogram-triggered cardiac MRF sequence with low flip angles, varying magnetization preparation, and spiral trajectory was acquired at 1.5 T to encode T-1, T-2, and T-1 rho simultaneously. The MRF images were reconstructed using low-rank inversion, regularized with a multicontrast patch-based higher-order reconstruction. Parametric maps were generated and matched in the singular value domain to extended phase graph-based dictionaries. The proposed approach was tested in phantoms and 10 healthy subjects and compared against conventional methods in terms of coefficients of determination and best fits for the phantom study, and in terms of Bland-Altman agreement, average values and coefficient of variation of T-1, T-2, and T-1 rho for the healthy subjects study. Results: The T-1, T-2, and T1 rho MRF values showed excellent correlation with conventional spin-echo and clinical mapping methods in phantom studies (r(2) > 0.97). Measured MRF values in myocardial tissue (mean +/- SD) were 1133 +/- 33 ms, 38.8 +/- 3.5 ms, and 52.0 +/- 4.0 ms for T-1, T-2 and T-1 rho, respectively, against 1053 +/- 47 ms, 50.4 +/- 3.9 ms, and 55.9 +/- 3.3 ms for T-1 modified Look-Locker inversion imaging, T-2 gradient and spin echo, and T-1 rho turbo field echo, respectively. Conclusion: A cardiac MRF approach for simultaneous quantification of myocardial T-1, T-2, and T-1 rho in a single breath-hold MR scan of about 16 seconds has been proposed. The approach has been investigated in phantoms and healthy subjects showing good agreement with reference spin echo measurements and conventional clinical maps.