FASt single‐breathhold 2D multislice myocardial T₁ mapping (FAST1) at 1.5T for full left ventricular coverage in three breathholds

Abstract

Background Conventional myocardial T1 mapping techniques such as modified Look–Locker inversion recovery (MOLLI) generate one T1 map per breathhold. T1 mapping with full left ventricular coverage may be desirable when spatial T1 variations are expected. This would require multiple breathholds, increasing patient discomfort and prolonging scan time. Purpose To develop and characterize a novel FASt single‐breathhold 2D multislice myocardial T1 mapping (FAST1) technique for full left ventricular coverage. Study Type Prospective. Population/Phantom Numerical simulation, agarose/NiCl2 phantom, 9 healthy volunteers, and 17 patients. Field Strength/Sequence 1.5T/FAST1. Assessment Two FAST1 approaches, FAST1‐BS and FAST1‐IR, were characterized and compared with standard 5‐(3)‐3 MOLLI in terms of accuracy, precision/spatial variability, and repeatability. Statistical Tests Kruskal‐Wallis, Wilcoxon signed rank tests, intraclass correlation coefficient analysis, analysis of variance, Student's t‐tests, Pearson correlation analysis, and Bland–Altman analysis. Results In simulation/phantom, FAST1‐BS, FAST1‐IR, and MOLLI had an accuracy (expressed as T1 error) of 0.2%/4%, 6%/9%, and 4%/7%, respectively, while FAST1‐BS and FAST1‐IR had a precision penalty of 1.7/1.5 and 1.5/1.4 in comparison with MOLLI, respectively. In healthy volunteers, FAST1‐BS/FAST1‐IR/MOLLI led to different native myocardial T1 times (1016 ± 27 msec/952 ±22 msec/987 ± 23 msec, P < 0.0001) and spatial variability (66 ± 10 msec/57 ± 8 msec/46 ± 7 msec, P < 0.001). There were no statistically significant differences between all techniques for T1 repeatability (P = 0.18). In vivo native and postcontrast myocardial T1 times in both healthy volunteers and patients using FAST1‐BS/FAST1‐IR were highly correlated with MOLLI (Pearson correlation coefficient ≥0.93). Data Conclusion FAST1 enables myocardial T1 mapping with full left ventricular coverage in three separated breathholds. In comparison with MOLLI, FAST1 yield a 5‐fold increase of spatial coverage, limited penalty of T1 precision/spatial variability, no significant difference of T1 repeatability, and highly correlated T1 times. FAST1‐IR provides improved T1 precision/spatial variability but reduced accuracy when compared with FAST1‐BS. Level of Evidence: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;51:492–504.

Simultaneous multi-slice T1 mapping using MOLLI with blipped CAIPIRINHA bSSFP

“…Applied to the MOLLI sequence, blipped-CAIPIRINHA SMS acceleration retains T1 accuracy compared to conventional MOLLI or literature values [13], for both myocardium and blood. By extension, CAIPIRINHA SMS-bSSFP has the potential to accelerate other T1 mapping techniques [15], [19], [28] as well as multiple CMR applications, including T2 mapping, cine as well as dynamic real-time imaging in the body. In this context, the use of AM multi-band RF modulation will be key to avoid artefacts as observed presently.…”

“…But for patients with arrhythmia, even a breath-hold of 15 seconds can be hard to achieve and maintain when done several times within the same examination. Multiple techniques have been proposed to accelerate MOLLI [15]- [24], however none so far have considered acquiring multiple slices simultaneously.…”

Cardiac phase-resolved late gadolinium enhancement imaging

“…Whole heart coverage requires repeated breath-holds, which hampers integration in the existing clinical workflow. Simultaneous-multi slice (SMS) imaging has recently been evaluated for improved spatial coverage in quantitative mapping of the heart ( 53 – 55 ). In functional LGE imaging SMS can facilitate improved coverage in fewer breath-holds for the benefit of easing clinical translation.…”

Quantification of balanced SSFP myocardial perfusion imaging at 1.5 T: Impact of the reference image

“…The fitting process is summarized in Figure 2. Because the signal dictionary is normalized, each pair of measured reference and SR signal values are first individually scaled to each signal dictionary entry (similar to Refs 28 and 29), using the following scaling factor ():where and represent the measured signal intensity of the reference image and the SR image, respectively; and and represent the modeled signal intensity of the reference image and the SR image, respectively. The scaled signal‐intensity values are then calculated as follows:…”