Optimization of 3D MR Fingerprinting with Cramér-Rao Lower Bound and Smooth Signal Evolutions for Efficient T1, T2, and T1ρ in the knee joint

Motivation: 3D-MR fingerprinting (3D-MRF) is effective for knee joint applications, especially with simultaneous T1, T2, and T1ρ mapping. However, the accuracy of the relaxation parameters and undersampling artifacts need to be addressed. Goal(s): Optimize 3D MRF, particularly flip angles (FAs) and spin lock times (TSLs), to enhance parameter quality while reducing undersampling artifacts. Approach: We combined Cramér-Rao Lower Bound (CRLB) optimization with a smoothness penalty in signal evolution. Results: Our preliminary findings show significant reductions in undersampling artifacts and improved parameter quality, closer to nominal values with NIST/ISMRM system phantom comparisons. Impact: This optimized 3D-MRF sequence can improve quantitative mapping in the knee joint, with more quantitative accuracy, due to CRLB optimization, and reduced undersampling artifacts, due to smooth signal evolutions.