RESUMO
BACKGROUND: Native myocardial T1 and T2 relaxation times are diagnostic tools used in clinical practice for adult and pediatric populations. Use of a mapping technique requires accurate knowledge of normal ranges in healthy patients, which is lacking in pediatric populations. PURPOSE: To establish normal values for native T1 and T2 mapping in healthy pediatric subjects of different ages and sex. STUDY TYPE: Prospective. POPULATION: Thirty-eight healthy children (9-18 years; mean age 14.0 ± 2.7). FIELD STRENGTH: Cardiac MR with a 3T scanner. T1 and T2 mapping using MyoMaps software. ASSESSMENT: T1 and T2 relaxation times were calculated from a 0.7-1.0 cm2 region of interest placed at the mid-ventricular short-axis slice in the interventricular septum by two observers. Inter- and intraobserver variability was assessed. STATISTICAL TESTS: The Student's t-test or the Mann-Whitney test for unpaired samples was applied to compare one continuous variable between two category groups. One-way analysis of variance (ANOVA) or a Kruskal-Wallis test was applied to compare one continuous variable between three category groups. Correlation between two continuous variables was assessed with a Pearson or Spearman test. RESULTS: The mean native T1 relaxation time was 1223 ± 29 msec and T2 relaxation time was 43 ± 4.5 msec. There was no correlation between T1 /T2 values and age or body surface area (for T1 P = 0.94 and 0.90 and for T2 P = 0.19 and 0.64, respectively). There was weak correlation between T1 values and body mass index (BMI) (r = 0.448, P = 0.005). T2 values were significantly higher in females compared with males (44.6 ± 4.2 vs. 40.4 ± 3.8 msec, P = 0.002). We found a significant rise of T2 relaxation time in the pubertal period (age 13-15 years) comparing to prepubertal (age 9-12 years). Inter- and intraobserver agreement of T1 (r = 0.93; r = 0.99) and T2 (r = 0.96; r = 0.95) were high. DATA CONCLUSION: We report normal values of native T1 and T2 relaxation times obtained with Myomaps software for 3T cardiac MR in a healthy pediatric population. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:912-918.
