Normal myocardial native T1 values in children using single-point saturation recovery and modified look-locker inversion recovery (MOLLI).

BACKGROUND: T1 mapping is useful to quantify diffuse myocardial processes such as fibrosis, edema, storage disorders, or hemochromatosis. Normal pediatric myocardial T1 values are scarce using modified Look-Locker inversion recovery (MOLLI) sequences and unavailable using Smart1Map, a single-point saturation recovery sequence that measures true T1 . PURPOSE/HYPOTHESIS: To establish normal pediatric myocardial T1 values by Smart1Map and to compare them with T1 by MOLLI. STUDY TYPE: Prospective cohort study. SUBJECTS: Thirty-four children and adolescents aged 8-18 years (14 males) without cardiovascular or inflammatory diseases. FIELD STRENGTH/SEQUENCES: 1.5T, MOLLI, Smart1Map. ASSESSMENT: Mean T1 values of the left ventricular myocardium, the interventricular septum, and the blood pool were measured with MOLLI and Smart1Map in basal, mid-ventricular, and apical short axis slices. STATISTICAL TESTS: T1 values were compared between locations and methods by paired samples t-tests, Wilcoxon signed ranks test, repeated-measures analysis of variance (ANOVA), or Friedman's test. Pearson's correlation coefficient was calculated. For interobserver variability, intraclass correlation coefficients and coefficients of variation were calculated, and Bland-Altman analyses were performed. RESULTS: T1 values were longer by Smart1Map than by MOLLI in all measured locations (myocardium: 1191-1221 vs. 990-1042 msec; all P < 0.001). T1 in basal vs. mid-ventricular slices differed both by MOLLI and by Smart1Map for myocardium and for blood (all P < 0.001). Myocardial T1 did not correlate with age, heart rate, right or left ventricular ejection fraction (all P > 0.05) by either method. Septal vs. total myocardial T1 values in each slice did not differ by MOLLI (basal P = 0.371; mid-ventricular P = 0.08; apical P = 0.378) nor by Smart1Map (basal P = 0.056; mid-ventricular P = 0.918; apical P = 0. 392), after artifacts had been carefully excluded. DATA CONCLUSION: We established pediatric normal native T1 values using the Smart1Map sequence and compared the results with T1 mapping with MOLLI. Septal T1 values did not differ from total myocardial T1 values in each of the myocardial slices. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:897-903.