Comparison of Echocardiographic and Cardiac Magnetic Resonance Imaging Measurements of Functional Single Ventricular Volumes, Mass, and Ejection Fraction (from the Pediatric Heart Network Fontan Cross-Sectional Study)††A list of participating institutions and investigators appears in the Appendix.

Abstract

Assessment of the size and function of the functional single ventricle (FSV) is a key element in the management of patients following the Fontan procedure. Measurement variability of ventricular mass, volume and ejection fraction between observers by echocardiography and CMR and their reproducibility between readers in these patients has not been described. From the 546 patients enrolled in the Pediatric Heart Network Fontan Cross-Sectional Study (mean age 11.9±3.4 years), 100 echocardiograms and 50 CMR studies were assessed for measurement reproducibility; 124 subjects with paired studies were selected for comparison between modalities. Inter-observer agreement for qualitative grading of ventricular function by echocardiography was modest for left ventricular (LV) morphology (kappa= 0.42) and weak for right ventricular (RV) morphology (kappa= 0.12). For quantitative assessment, high intra-class correlation coefficients (ICC) were found for echocardiographic inter-observer (LV= 0.87–0.92; RV= 0.82–0.85) agreement of systolic and diastolic volumes, respectively. In contrast, ICCs for LV and RV mass were moderate (LV= 0.78; RV= 0.72). The corresponding ICCs by CMR were high (LV= 0.96; RV= 0.85). Volumes by echocardiography averaged 70% of CMR values. Interobserver reproducibility of EF was similar for both modalities. Although the absolute mean difference between modalities for ejection fraction was small (<2%), 95% limits of agreement were wide. In conclusion, agreement between observers of qualitative FSV function by echocardiography is modest. Measurements of FSV volume by 2D echocardiography underestimate CMR measurements but their reproducibility is high. Echocardiographic and CMR measurements of FSV EF demonstrate similar interobserver reproducibility whereas measurements of FSV mass and LV diastolic volume are more reproducible by CMR.