Fast, Precise, and Accurate Myocardial T Mapping Using a Radial MOLLI Sequence with FLASH Readout

Purpose: Quantitative cardiac MRI, and more particularly T 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 relaxation recovery curve, to which a dictionary-fitting approach was applied to estimate T . 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 map acquisition time down to five heartbeats, while exhibiting a higher degree of accuracy and a comparable precision on T value estimation than the conventional modified Look-Locker inversion recovery sequence. The FLASH readout demonstrated a better robustness to B inhomogeneities than TrueFISP, and was therefore preferred for in vivo acquisitions.

Conclusions: This sequence represents a good candidate for ultrafast acquisition of myocardial T maps. Magn Reson Med 79:1387-1398, 2018. © 2017 International Society for Magnetic Resonance in Medicine.