Accuracy and Reproducibility of Real-Time Three-Dimensional Echocardiography for Assessment of Right Ventricular Volumes and Ejection Fraction in Children Xiuzhang Lu, Vyacheslav Nadvoretskiy, Liping Bu, Alan Stolpen, Nancy Ayres, Ricardo H. Pignatelli, John P. Kovalchin, Michelle Grenier, Berthold Klas, and Shuping Ge, MD, Houston, Texas; Iowa City, Iowa; and Munich, Germany Background: Measurement of right ventricular (RV) volumes and ejection fraction (EF) by two-dimensional echocardiography has limited accuracy and reproducibility because of the complex RV geometry. Objectives: This study sought to validate real-time three-dimensional echocardiography (RT3DE) using a disk summation method for assessment of RV volumes and RVEF in children by comparing it with magnetic resonance imaging (MRI) measurements. Methods: A total of 20 children (mean age 10.6  2.8 years) were studied. Transthoracic RT3DE was performed using a RT3DE system to acquire full-volume RT3DE data sets from apical windows and data were processed offline using a software package. RV end-systolic volume and end-diastolic volume (EDV) were measured using a disk summation method by manually tracing the endocardial borders. RVEF was calculated as: RVEF = (EDV - end-systolic volume)/EDV  100%. All participants also underwent MRI studies for comparison of RV indexes. Results: Of the 20 children, 3 were excluded because of poor or incomplete RV images (two RT3DE and one MRI study). For the remaining 17 children, good correlation and agreement between RT3DE and MRI were found (RVEDV: r = 0.98, P  .001, mean difference =-7.0  9.0 mL, P  .01; RV end-systolic volume: r = 0.96, P  .001, mean difference =-3.2  7.1 mL, P  .05; RVEF: r = 0.89, P  .001, mean difference =-0.3  7.1%, P  .05). The intraobserver and the interobserver variabilities ranged from -1.1% to 5.8%. Conclusion: Measurement of RV volumes and EF by RT3DE is feasible, accurate, and reproducible in children compared with MRI measurements. The right ventricle (RV) plays a critical role in congenital heart diseases in children, and RV dysfunction develops in many patients and leads to considerable morbidity and mortality. RV volumes and ejection fraction (EF) are the most widely used indexes to assess RV function; therefore, reliable determination of these RV indexes is essential for prognosis, guiding therapy, and longitudinal follow-up in these patients. 1-4 Two-dimensional (2D) echocardiography (2DE) is the mainstay for analysis of RV function. However, 2DE only provides a qualitative assessment of RV volumes and systolic function. Quantitative 2DE methods have limited accuracy and reproducibility because of the complex RV geometry. 5-14 First described by Dekker et al 15 in 1974, three-dimensional (3D) echocardiography (3DE) has been validated for assessment of cardiac anatomy and function. 16-21 More recently, real-time 3DE (RT3DE) is available for investigational and clinical use. 21,22 The feasibility, accu- racy, and reproducibility of the quantification of left ventricular (LV) volumes and function using RT3DE have been validated in adults and children. 23-25 However, the feasibility, accuracy, and reproducibility of measuring RV volumes and EF by RT3DE in children are un- known. The purpose of this study was to validate RT3DE for evaluation of RV volumes and RVEF in children and to determine the feasibility, accuracy, and reproducibility of this technology using a disk summa- tion method by comparing the results with magnetic resonance imaging (MRI) measurements, a technique currently considered as the clinical gold standard for this purpose. From the Baylor College of Medicine and Texas Children’s Hospital, Houston, Texas (X.L., V.N., N.A., R.H.P., J.P.K., M.G., S.G.); University of Iowa, Iowa City, Iowa (L.B., A.S.); TomTec Imaging Systems, Munich, Germany (B.K.); and Texas Heart Institute/St Luke’s Episcopal Hospital, Houston, Texas (S.G.). Reprint requests: Shuping Ge, MD, The Lillie Frank Abercrombie Section of Cardiology, Department of Pediatrics, Baylor College of Medicine and Texas Children’s Hospital, 6621 Fannin, MC 19345-C, Houston, TX 77030 (E-mail: shupingg@bcm.tmc.edu). 0894-7317/$34.00 Copyright 2008 by the American Society of Echocardiography. doi:10.1016/j.echo.2007.05.009 84