Comparison of different cardiovascular magnetic resonance sequences for native myocardial T1 mapping at 3T

Abstract

BackgroundT1 mapping based on cardiovascular magnetic resonance (CMR) is a novel approach using the magnetic relaxation T1 time as a quantitative marker for myocardial tissue composition. Various T1 mapping sequences are being used, with different strengths and weaknesses. Data comparing different sequences head to head however are sparse.MethodsWe compared three T1 mapping sequences, ShMOLLI, MOLLI and SASHA in phantoms and in a mid-ventricular slice of 40 healthy individuals (mean age 59 ± 7 years, 45 % male) with low (68 %) or moderate cardiovascular risk. We calculated global and segmental T1 in vivo through exponential curve fitting and subsequent parametric mapping. We also analyzed image quality and inter-observer reproducibility.ResultsThere was no association of T1 with cardiovascular risk groups. T1 however differed significantly depending on the sequence, with SASHA providing consistently higher mean values than ShMOLLI and MOLLI (1487 ± 36 ms vs. 1174 ± 37 ms and 1199 ± 28 ms, respectively; p < 0.001). This difference between sequences was much smaller in phantom measurements. In patients, segmental values were lower in the anterior wall for all sequences. Image quality, in general good for the steady-state-free-precession readouts in all sequences, was lower for SASHA parametric maps. On multivariate regression analysis, a longer T1 measured by MOLLI was correlated with lower ejection fraction and female gender. Inter-observer variability as assessed by intra-class correlation coefficients was excellent for all sequences (ShMOLLI: 0.995; MOLLI: 0.991; SASHA: 0.961; all p < 0.001).ConclusionIn a cross-sectional population with low to moderate cardiovascular risk, we observed a variation in T1 mapping results between inversion-recovery vs. saturation-recovery sequences in vivo, which were less evident in phantom images, despite a small interobserver variability. Thus, physiological factors, most likely related to B1 inhomogeneities, and tissue-specific properties, like magnetization transfer, that impact T1 values in vivo, render phantom validation insufficient, and have to be further investigated for a better understanding of the clinical utility of different T1 mapping approaches.Trial registration“Canadian Alliance For Healthy Hearts and Minds” – ClinicalTrials.gov NCT02220582; registered August 18, 2014.

Normal values of native T1 and T2 relaxation times on 3T cardiac MR in a healthy pediatric population aged 9–18 years

“…The lack of influence of age on the native T 1 and T 2 relaxation time values in our study could derive from the fact that, unlike in studies on adult populations, we analyzed only a small age range (11 years). 10,15,17 Mean T 1 relaxation time in children seems to be higher and T 2 relaxation time similar in comparison with those studies. 14 We have found that in children T 1 relaxation time was not influenced by sex, but T 2 relaxation time was higher in female than in male children.…”

“…7 Native T 1 reference values are higher for 3T than 1.5T scanners 10,11 and depend on the scanning sequence used with highest values for SASHA and lowest for ShMOLLI, with the MOLLI technique (as used in this study) in between. All of the reference values for T 1 and T 2 relaxation times presented before included only adult populations, reported mainly T 1 relaxation times and were performed mostly on 1.5T scanners.…”

“…8 T 1 -mapping has the potential to improve risk stratification in Kawasaki disease or Duchenne muscular dystrophy by showing areas of myocardial fibrosis earlier than LGE. [10][11][12] In recent years, there have been reports presenting established normal values for T 1 and T 2 , but none of them included pediatric populations. They differ depending on the mapping technique used (saturation recovery single-shot acquisition [SASHA], modified Look-Locker inversion recovery [MOLLI], and shortened modified [sh]MOLLI), the vendor of the scanner, the magnetic field strength (1.5 vs. 3T), and are also influenced by physiological parameters such as sex or age.…”

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

“…In these approaches, multiple images with different T 1 ‐weightings are acquired and fit in a pixelwise manner to a physical model of the MR signal evolution . Inversion recovery (IR)‐based approaches such as modified Look–Locker inversion recovery (MOLLI) are commonly used due to their high precision, reproducibility, and map quality . In these techniques, multiple (usually 7–13) 2D single‐shot electrocardiogram (ECG)‐triggered images of the same slice are acquired at different inversion times (TIs) in a single breathhold and used to generate one T 1 map.…”

Fast myocardial T1 mapping using shortened inversion recovery based schemes

“…The modified Look–Locker inversion recovery (MOLLI) sequence and its variations, such as the shortened MOLLI (ShMOLLI) and other modified MOLLI schemes, are inversion recovery based techniques. Although MOLLI T 1 times have been shown to be dependent on several parameters including T 2 , magnetization transfer, off‐resonance, inversion factor, and heart rate (HR), this approach is commonly used for myocardial T 1 mapping due to its high reproducibility/high repeatability, high precision/low spatial variability, and high map quality/low artifact level …”