Magnetic resonance fingerprinting with quadratic RF phase for measurement of T2* simultaneously with δf,T1, and T2

Purpose: This study explores the possibility of using a gradient moment balanced sequence with a quadratically varied RF excitation phase in the magnetic resonance fingerprinting (MRF) framework to quantify T-2* in addition to delta(f), T-1, and T-2 tissue properties. Methods: The proposed quadratic RF phase-based MRF method (qRF-MRF) combined a varied RF excitation phase with the existing balanced SSFP (bSSFP)-based MRF method to generate signals that were uniquely sensitive to delta(f), T-1, T-2, as well as the distribution width of intravoxel frequency dispersion, Gamma. A dictionary, generated through Bloch simulation, containing possible signal evolutions within the physiological range of delta(f), T-1, T-2, and G, was used to perform parameter estimation. The estimated T-2 and G were subsequently used to estimate T-2*. The proposed method was evaluated in phantom experiments and healthy volunteers (N = 5). Results: The T-1 and T-2 values from the phantom by qRF-MRF demonstrated good agreement with values obtained by traditional gold standard methods (r(2) = 0.995 and 0.997, respectively; concordance correlation coefficient = 0.978 and 0.995, respectively). The T-2* values from the phantom demonstrated good agreement with values obtained through the multi-echo gradient-echo method (r(2) = 0.972, concordance correlation coefficient = 0.983). In vivo qRF-MRF-measured T-1, T-2, and T-2* values were compared with measurements by existing methods and literature values. Conclusion: The proposed qRF-MRF method demonstrated the potential for simultaneous quantification of delta(f), T-1, T-2, and T-2* tissue properties.