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

## TL;DR

A new MRI technique called MFA offers more stable and motion-resistant T1 mapping of the heart compared to traditional methods, especially in patients with irregular heartbeats.

## Contribution

The MFA sequence is introduced as a frequency-independent and motion-robust alternative to the MOLLI sequence for myocardial T1 mapping.

## Key findings

- MFA showed stable T1 values across varying heart rates, unlike MOLLI which had significant heart rate dependency.
- MFA was less affected by motion artifacts and showed consistent results in challenging regions like basal segments.
- MOLLI provided higher precision but exhibited sex-related differences and greater variability under motion.

## Abstract

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.

The multiflip angle (MFA) sequence provides a frequency‐independent and motion‐robust alternative to the MOLLI sequence for myocardial T1 mapping. Although MOLLI demonstrated higher measurement precision, it showed heart rate dependency and sex‐related differences in T1 values. In contrast, MFA maintained stable T1 values across varying heart rates and exhibited reduced susceptibility to motion artifacts. These findings highlight MFA's potential for improved myocardial characterization, particularly in patients with arrhythmias or during stress testing, warranting further clinical evaluation.