Simultaneous Mapping of T₁ and T₂ Using Cardiac Magnetic Resonance Fingerprinting in a Cohort of Healthy Subjects at 1.5T

Abstract

Background Cardiac MR fingerprinting (cMRF) is a novel technique for simultaneous T1 and T2 mapping. Purpose To compare T1/T2 measurements, repeatability, and map quality between cMRF and standard mapping techniques in healthy subjects. Study Type Prospective. Population In all, 58 subjects (ages 18–60). Field Strength/Sequence cMRF, modified Look–Locker inversion recovery (MOLLI), and T2‐prepared balanced steady‐state free precession (bSSFP) at 1.5T. Assessment T1/T2 values were measured in 16 myocardial segments at apical, medial, and basal slice positions. Test–retest and intrareader repeatability were assessed for the medial slice. cMRF and conventional mapping sequences were compared using ordinal and two alternative forced choice (2AFC) ratings. Statistical Tests Paired t‐tests, Bland–Altman analyses, intraclass correlation coefficient (ICC), linear regression, one‐way analysis of variance (ANOVA), and binomial tests. Results Average T1 measurements were: basal 1007.4±96.5 msec (cMRF), 990.0±45.3 msec (MOLLI); medial 995.0±101.7 msec (cMRF), 995.6±59.7 msec (MOLLI); apical 1006.6±111.2 msec (cMRF); and 981.6±87.6 msec (MOLLI). Average T2 measurements were: basal 40.9±7.0 msec (cMRF), 46.1±3.5 msec (bSSFP); medial 41.0±6.4 msec (cMRF), 47.4±4.1 msec (bSSFP); apical 43.5±6.7 msec (cMRF), 48.0±4.0 msec (bSSFP). A statistically significant bias (cMRF T1 larger than MOLLI T1) was observed in basal (17.4 msec) and apical (25.0 msec) slices. For T2, a statistically significant bias (cMRF lower than bSSFP) was observed for basal (–5.2 msec), medial (–6.3 msec), and apical (–4.5 msec) slices. Precision was lower for cMRF—the average of the standard deviation measured within each slice was 102 msec for cMRF vs. 61 msec for MOLLI T1, and 6.4 msec for cMRF vs. 4.0 msec for bSSFP T2. cMRF and conventional techniques had similar test–retest repeatability as quantified by ICC (0.87 cMRF vs. 0.84 MOLLI for T1; 0.85 cMRF vs. 0.85 bSSFP for T2). In the ordinal image quality comparison, cMRF maps scored higher than conventional sequences for both T1 (all five features) and T2 (four features). Data Conclusion This work reports on myocardial T1/T2 measurements in healthy subjects using cMRF and standard mapping sequences. cMRF had slightly lower precision, similar test–retest and intrareader repeatability, and higher scores for map quality. Evidence Level 2 Technical Efficacy Stage 1 J. Magn. Reson. Imaging 2020;52:1044–1052.

Myocardial T1 and T2 quantification and water–fat separation using cardiac MR fingerprinting with rosette trajectories at 3T and 1.5T

“…Moreover, both methods found T 1 measurements higher than MOLLI and T 2 measurements lower than conventional T 2 mapping sequences, which is consistent with previous cMRF reports. 55,72 Proton density fat fraction quantification was also shown to be possible using the Dixon cMRF, possibly due to the use of a 6-peak fat model in the water-fat separation step.…”

Deep learning reconstruction for cardiac magnetic resonance fingerprinting T1 and T2 mapping

“…Seventh, no comparison was made between deep learning cMRF and conventional T 1 /T 2 mapping techniques, although prior work has compared dictionary-based cMRF with conventional mapping. 13 Finally, the in vivo results were limited to healthy subjects, and additional validation of the deep learning cMRF reconstruction should be performed in patients with known cardiac pathologies.…”

“…The cMRF sequence has been described in previous work, 13 although the breath-hold duration here was reduced from 15 to 10 heartbeats. A fast imaging with steady state precession (FISP) readout is used that is relatively insensitive to off-resonance because of the unbalanced gradient moment on the sliceselect axis.…”

“…The scans were performed on a 1.5T MRI scanner (MAGNETOM Aera, Siemens Healthineers, Germany) at a medial short-axis slice position during an endexpiration breath-hold with a 192 × 192 matrix size, 300 mm 2 FOV, and 1.6 × 1.6 × 8.0 mm 3 resolution. T 1 and T 2 maps were reconstructed in 2 ways: (1) using the Bloch equations to simulate a scan-specific dictionary and performing pattern matching as in previous cMRF work, 13 hereafter called "dictionary matching," and (2) using the deep learning reconstruction. The dictionary contained 23,345 entries with T 1 [10:10:2000, 2020:20:3000] ms and T 2 [4:2:100, 105:5:300, 320:20:500] ms.…”

Editorial for “Simultaneous Mapping of T1 and T2 Using Cardiac Magnetic Resonance Fingerprinting in a Cohort of Healthy Subjects at 1.5T”

“…In this issue of the Journal of Magnetic Resonance Imaging , Hamilton et al 8 sought to compare T 1 /T 2 measurements, repeatability, and image quality of their MRF technique to clinically available MOLLI and T 2 Prep‐SSFP sequences in 58 healthy young adult subjects with no known cardiovascular disease. Like their original article, the current study demonstrates the potential of MRF in myocardial tissue characterization.…”