Fast, precise, and accurate myocardial T₁ mapping using a radial MOLLI sequence with FLASH readout

Purpose Quantitative cardiac MRI, and more particularly T 1 mapping, has become a most important modality to characterize myocardial tissue. In this work, the value of a radial variant of the conventional modified Look‐Locker inversion recovery sequence (raMOLLI) is demonstrated. Methods The raMOLLI acquisition scheme consisted of five radial echo trains of 80 spokes acquired using either a fast low‐angle shot (FLASH) or a true fast imaging with steady‐state‐precession (TrueFISP) readout at different time points after a single magnetization inversion. View sharing combined with a compressed sensing algorithm allowed the reconstruction of 50 images along the T 1 relaxation recovery curve, to which a dictionary‐fitting approach was applied to estimate T 1 . The sequence was validated on a nine‐vial phantom, on 19 healthy subjects, and one patient suffering from dilated cardiomyopathy. Results The raMOLLI sequence allowed a significant decrease of myocardial T 1 map acquisition time down to five heartbeats, while exhibiting a higher degree of accuracy and a comparable precision on T 1 value estimation than the conventional modified Look‐Locker inversion recovery sequence. The FLASH readout demonstrated a better robustness to B 0 inhomogeneities than TrueFISP, and was therefore preferred for in vivo acquisitions. Conclusions This sequence represents a good candidate for ultrafast acquisition of myocardial T 1 maps. Magn Reson Med 79:1387–1398, 2018.