Magnetic resonance imaging reference values for cardiac morphology, function and tissue composition in adolescents

Abstract

Background: Cardiovascular magnetic resonance (CMR) is a precise tool for the assessment of cardiac anatomy, function, and tissue composition. However, studies providing CMR reference values in adolescence are scarce. We aim to provide sex-specific CMR reference values for biventricular and atrial dimensions and function and myocardial relaxation times in this population.

Methods: Adolescents aged 15-18 years with no known cardiovascular disease underwent a non-contrast 3-T CMR scan between March 2021 and October 2021. The imaging protocol included a cine steady-state free-precession sequence for the analysis of chamber size and function, as well as T2-GraSE and native MOLLI T1-mapping for the characterization of myocardial tissue.

Findings: CMR scans were performed in 123 adolescents (mean age 16 ± 0.5 years, 52% girls). Mean left and right ventricular end-diastolic indexed volumes were higher in boys than in girls (91.7 ± 11.6 vs 78.1 ± 8.3 ml/m², p < 0.001; and 101.3 ± 14.1 vs 84.1 ± 10.5 ml/m², p < 0.001), as was the indexed left ventricular mass (48.5 ± 9.6 vs 36.6 ± 6.0 g/m², p < 0.001). Left ventricular ejection fraction showed no significant difference by sex (62.2 ± 4.1 vs 62.8 ± 4.2%, p = 0.412), whereas right ventricular ejection fraction trended slightly lower in boys (55.4 ± 4.7 vs. 56.8 ± 4.4%, p = 0.085). Indexed atrial size and function parameters did not differ significantly between sexes. Global myocardial native T1 relaxation time was lower in boys than in girls (1215 ± 23 vs 1252 ± 28 ms, p < 0.001), whereas global myocardial T2 relaxation time did not differ by sex (44.4 ± 2.0 vs 44.1 ± 2.4 ms, p = 0.384). Sex-stratified comprehensive percentile tables are provided for most relevant cardiac parameters.

Interpretation: This cross-sectional study provides overall and sex-stratified CMR reference values for cardiac dimensions and function, and myocardial tissue properties, in adolescents. This information is useful for clinical practice and may help in the differential diagnosis of cardiac diseases, such as cardiomyopathies and myocarditis, in this population.

Funding: Instituto de Salud Carlos III (PI19/01704).

Keywords: Adolescent; Differential diagnosis; Magnetic resonance; Pediatrics; Reference values; Ventricular function.

Fig. 1

Ventricular tracing in cardiovascular magnetic resonance cine sequences. Ventricular slices and tracing from base (top left) to apex (bottom right) of the same participant during the end-diastolic and end-systolic phases of the cardiac cycle.

Fig. 2

Atrial tracing in cardiovascular magnetic resonance cine sequences. Representative 2-chamber (A, B, C) and 4-chamber (D, E, F) long-axis views. For the calculation of atrial function, the left atrium (LA) and right atrium (RA) were assessed in the maximum-volume, pre-contraction-volume, and minimum-volume phases.

Fig. 3

Parametric mapping manual contouring. Representative T1 (A) and T2 (B) mapping assessed in a mid-ventricular slice from the same participant. The myocardium was divided into 6 segments according to the American Heart Association (AHA) segment model, indicated by the following numbers: 1 (mid anterior), 2 (mid anteroseptal), 3 (mid inferoseptal), 4 (mid inferior), 5 (mid inferolateral), and 6 (mid anterolateral).

Fig. 4

Flow diagram of participants. CMR, cardiovascular magnetic resonance; EnIGMA, Early ImaGing Markers of unhealthy lifestyles in Adolescents.

Fig. 5

Cardiovascular magnetic resonance reference values in adolescents. Cardiovascular magnetic resonance (CMR) parameters were obtained from 123 adolescents aged from 15 to 18 years in order to obtain reference values for this population. Median values are shown in green for all parameters displayed. For LVEF and RVEF, P10 and P3 values are shown in yellow and red, respectively. For LVEDVi, LVESVi, RVEDVi, RVESVi, native T1 and T2 mapping, P90 and P97 values are shown in yellow and red, respectively. CMR, cardiovascular magnetic resonance; LVEF, left ventricular ejection fraction; RVEF, right ventricular ejection fraction; LVEDVi, indexed left ventricular end-diastolic volume; LVESVi, indexed left ventricular end-systolic volume; RVEDVi, indexed right ventricular end-diastolic volume; RVESVi, indexed right ventricular end-systolic volume; i, indexed to body surface area; P, percentile.