Advancing Myocardial T1 Mapping: A Comparative Study of the Frequency-Independent MFA Sequence and Standard MOLLI.

T1 mapping is essential for detecting myocardial changes, but standard methods like the MOLLI sequence are limited by heart rate dependency and sensitivity to motion artifacts. This study introduces the multiflip angle (MFA) sequence as a novel alternative, aiming to provide frequency-independent and robust T1 mapping, particularly in challenging cardiac conditions. The novel MFA sequence was validated using nickel (II) chloride phantoms and systematically compared with the standard MOLLI sequence in 20 healthy volunteers using a 1.5 Tesla Philips Achieva MRI system. T1 values were assessed at rest and under mild physical exertion to evaluate frequency dependency, measurement precision, and robustness to motion artifacts. The MFA sequence demonstrated robust frequency independence, with T1 values remaining stable across varying heart rates, unlike MOLLI, which exhibited a significant correlation between T1 values and heart rate (R = 0.52, p < 0.001), and sex (3% higher values in females; p = 0.044). Although both sequences showed no statistically significant age-related differences, MOLLI yielded more precise T1 measurements with lower variability compared to MFA. Additionally, MFA exhibited reduced susceptibility to motion artifacts, maintaining consistent values across myocardial regions and physiological conditions, particularly in basal segments where MOLLI showed greater variability. The MFA sequence offers a frequency-independent and motion-robust alternative to the MOLLI sequence for myocardial T1 mapping. Although the MOLLI sequence provides higher precision, MFA's stability across varying heart rates and resistance to motion artifacts positions it as a promising option, particularly for patients with arrhythmias or during stress testing. Further investigation is warranted to refine its clinical applications.