PURPOSE: To develop an arrhythmia-insensitive rapid (AIR) cardiac T1 mapping 
pulse sequence for quantification of diffuse fibrosis.
METHODS: An arrhythmia-insensitive cardiac T1 mapping pulse sequence was 
developed based on saturation recovery T1 weighting, which is inherently 
insensitive to heart rate and rhythm, and two single-shot balanced steady-state 
free precession image acquisitions with centric k-space ordering, where T1 
calculation is inherently insensitive to T2 effects. Its performance against 
conventional cardiac T1 mapping based on inversion recovery (i.e., MOLLI) is 
compared. Phantom experiments (T1 ranging from 535 to 2123 ms) were performed 
with heart rate and rhythm simulated at 60 and 120 beats per minute (bpm) and 
arrhythmia using an external triggering device. Ten human subjects and 17 large 
animals were scanned precontrast and 5, 10, and 15 min after contrast agent 
administration.
RESULTS: Compared with the reference T1 mapping, AIR yielded lower normalized 
root-mean-square error than MOLLI (8% vs. 3%, respectively, at 60 bpm, 28% vs. 
3%, respectively, at 120 bpm, and 22% vs. 3%, respectively, at arrhythmia). In 
vivo studies showed that T1 measurements made by MOLLI and AIR were strongly 
correlated (r = 0.99) but in poor agreement (mean difference = 161.8 ms, upper 
and lower 95% limits of agreements = 347.5 ms and -24.0 ms).
CONCLUSION: Our AIR pulse sequence may be clinically useful for assessment of 
diffuse myocardial fibrosis in patients.