Slice Profile and B1 Corrections in 2D Magnetic Resonance Fingerprinting

Purpose: The goal of this study is to characterize and improve the accuracy of 2D magnetic resonance fingerprinting (MRF) scans in the presence of slice profile (SP) and B-1 imperfections, which are two main factors that affect quantitative results in MRF. Methods: The SP and B-1 imperfections are characterized and corrected separately. The SP effect is corrected by simulating the radiofrequency pulse in the dictionary, and the B-1 is corrected by acquiring a B-1 map using the Bloch-Siegert method before each scan. The accuracy, precision, and repeatability of the proposed method are evaluated in phantom studies. The effects of both SP and B-1 imperfections are also illustrated and corrected in the in vivo studies. Results: The SP and B-1 corrections improve the accuracy of the T-1 and T-2 values, independent of the shape of the radiofrequency pulse. The T-1 and T-2 values obtained from different excitation patterns become more consistent after corrections, which leads to an improvement of the robustness of the MRF design. Conclusion: This study demonstrates that MRF is sensitive to both SP and B-1 effects, and that corrections can be made to improve the accuracy of MRF with only a 2-s increase in acquisition time. (C) 2017 International Society forMagnetic Resonance inMedicine.