Interleaved 23Na/1H (pTx) MRI of the human heart at 7 Tesla

Motivation: Interleaved dual-nuclear acquisition enables time-efficient 23Na and 1H cardiac MRI within one measurement. However, at 7T the reduced excitation wavelengths can lead to flip angle (FA) inhomogeneities in 23Na MRI and even to signal dropouts in 1H MRI. Both effects impair a reproducible quantitative evaluation of the myocardial 23Na signal. Goal(s): To reduce FA inhomogeneities for interleaved 23Na/1H MRI. Approach: We included three different pTx pulses in 1H MRI of the interleaved sequence and introduced a fast 23Na FA mapping. Results: All three pTx pulses improved the 1H FA homogeneity and 23Na images showed better signal homogeneity after FA correction. Impact: Interleaved 23Na/1H (pTx) MRI in combination with additional fast 23Na FA mapping is less prone to FA inhomogeneities and by that should enable reliable quantification of myocardial 23Na signal within clinically feasible acquisition times.