Normal myocardial native T$_{1}$ values in children using single-point saturation recovery and modified look-locker inversion recovery (MOLLI)

Abstract

BACKGROUND

T$_{1}$ mapping is useful to quantify diffuse myocardial processes such as fibrosis, edema, storage disorders, or hemochromatosis. Normal pediatric myocardial T$_{1}$ values are scarce using modified Look-Locker inversion recovery (MOLLI) sequences and unavailable using Smart1Map, a single-point saturation recovery sequence that measures true T$_{1}$ .

PURPOSE/HYPOTHESIS

To establish normal pediatric myocardial T$_{1}$ values by Smart1Map and to compare them with T$_{1}$ 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 T$_{1}$ 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

T$_{1}$ 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

T$_{1}$ values were longer by Smart1Map than by MOLLI in all measured locations (myocardium: 1191-1221 vs. 990-1042 msec; all P < 0.001). T$_{1}$ in basal vs. mid-ventricular slices differed both by MOLLI and by Smart1Map for myocardium and for blood (all P < 0.001). Myocardial T$_{1}$ did not correlate with age, heart rate, right or left ventricular ejection fraction (all P > 0.05) by either method. Septal vs. total myocardial T$_{1}$ 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 T$_{1}$ values using the Smart1Map sequence and compared the results with T$_{1}$ mapping with MOLLI. Septal T$_{1}$ values did not differ from total myocardial T$_{1}$ values in each of the myocardial slices.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019.