Investigating and reducing the effects of confounding factors for robust T and T mapping with cardiac MR fingerprinting.

This study aims to improve the accuracy and consistency of T and T measurements using cardiac MR Fingerprinting (cMRF) by investigating and accounting for the effects of confounding factors including slice profile, inversion and T preparation pulse efficiency, and B. The goal is to understand how measurements with different pulse sequences are affected by these factors. This can be used to determine which factors must be taken into account for accurate measurements, and which may be mitigated by the selection of an appropriate pulse sequence. Simulations were performed using a numerical cardiac phantom to assess the accuracy of over 600 cMRF sequences with different flip angles, TRs, and preparation pulses. A subset of sequences, including one with the lowest errors in T and T maps, was used in subsequent analyses. Errors due to non-ideal slice profile, preparation pulse efficiency, and B were quantified in Bloch simulations. Corrections for these effects were included in the dictionary generation and demonstrated in phantom and in vivo cardiac imaging at 3 T. Neglecting to model slice profile and preparation pulse efficiency led to underestimated T and overestimated T for most cMRF sequences. Sequences with smaller maximum flip angles were less affected by slice profile and B. Simulating all corrections in the dictionary improved the accuracy of T and T phantom measurements, regardless of acquisition pattern. More consistent myocardial T and T values were measured using different sequences after corrections. Based on these results, a pulse sequence which is minimally affected by confounding factors can be selected, and the appropriate residual corrections included for robust T and T mapping.