Locally Linearized Approximation of RF Pulse Propagators for Faster Simulation of Magnetization Dynamics With Slice Profile Effects in 2D MR Fingerprinting

Purpose: The objective for this study is to decrease the computation time of magnetic resonance fingerprinting dictionary computations that include slice profile effects.

Theory and methods: A locally linearized approximation to RF pulse propagators across RF scaling factors was derived and used to decrease the computational burden of MRF dictionary computation. MR fingerprinting phantom experiments were carried out at 3T to assess the practical feasibility of using dictionaries approximated with the proposed approach.

Results: Using linearizations at 10 $B_1^{+}$ scaling factors produced root mean square differences in estimated $T_1$ and $T_2$ of 1.17% and 1.98%, respectively, between dictionaries generated using a full Bloch simulation and the locally linear approximation while decreasing computation time by a factor of 10.

Conclusion: The proposed locally linear approximation significantly accelerates slice-profile-aware MRF simulations while maintaining high accuracy, enabling practical incorporation of realistic RF pulse effects into large-scale dictionary computations.

MR fingerprinting; RF pulse simulation; quantitative MRI.