Agreement and reproducibility of quantitative values depend on acquisition parameters in magnetic resonance...

This study evaluated the effects of acquisition parameters on relaxation times measured using magnetic resonance fingerprinting (MRF). MRF enables the simultaneous acquisition of multiple quantitative maps by varying the flip angle (FA) and repetition time (TR) in a pseudo-random manner and by pattern-matching signal evolutions to a pre-calculated dictionary. To assess parameter dependency, multiple acquisition protocols were generated with varying numbers of echoes (500, 1000, 1500, and 3000), TR widths (12-14 ms, 12-17 ms, and 12-20 ms), and maximum FA ranges using the MRF Development Kit. The International Society for Magnetic Resonance in Medicine/National Institute of Standards and Technology system phantom was scanned ten times per condition on a 3-Tesla scanner. Coefficients of variation (CVs) and agreement were calculated for T1 and T2 values. Results indicated that 1500 and 3000 echoes produced comparable agreement and reproducibility (agreement within ± 7.77% and CVs ≤ 1.13% for both T1 and T2). At 500 echoes, CVs increased substantially and agreement decreased, with T2 values being more affected than T1 values. At 1000 echoes with an expanded TR width (12-20 ms), CVs were 1.15% or less and agreement was within ± 5.20%, comparable to higher echo counts while reducing scan time by approximately 20%. This study demonstrated that the number of echoes, TR width, and maximum FA significantly influence T1 and T2 agreement and reproducibility, suggesting that expanding the TR range can stabilize relaxation times even with fewer echoes.