Normative data for myocardial native T1 and extracellular volume fraction in children

Purpose: To establish normative data for myocardial T1, including extracellular volume (ECV) fraction, in healthy children. Materials and Methods: In this retrospective, single-center study, T1 mapping data were collected from 48 healthy pediatric patients (14 years ± 3 [standard deviation]; range, 9–18 years; 27 of 48 [56%] male) referred for cardiac screening 1.5-T MRI between 2014 and 2017. T1 relaxometry was performed using a 5(number of heartbeats [nHB])3 modified Look-Locker inversion recovery (MOLLI) sequence, where nHB was three to five heartbeats depending on the heart rate, and was repeated 15 minutes following the administra-tion of 0.2 mmol per kilogram of body weight of gadobenate dimeglumine, with 19 patients receiving contrast material. T1 values were calculated using a curve-fitting algorithm on average region-of-interest signal and corrected for imperfect inversion pulse effi-ciency. Comparisons within patients were performed with paired Student t test, between groups with unpaired Student t test or Mann-Whitney U test, and linear regression was performed to examine for associations with other variables. Results: Average native T1 was 1008 msec ± 31, with a nonsignificant increase in females (1017 msec ± 27 vs 1001 msec ± 33, P = .066). Average ECV was 20.8% ± 2.4, with a nonsignificant increase in values in females (21.7% ± 1.9 vs 20.0% ± 2.6, P = .123). T1 and ECV values were increased in the septum versus the free wall. Conclusion: Normative data are presented for myocardial native T1 and ECV using the MOLLI T1 mapping sequence at 1.5 T.