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Repeatability and Reproducibility of Fetal Cardiac Ventricular Volume Calculations Using Spatiotemporal Image Correlation and Virtual Organ Computer-Aided Analysis

Perinatology Research Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, US Department of Health and Human Services, Detroit, Michigan USA (N.H., R.R., S.S.H., P.M., J.P.K., T.C., E.V., J.E., F.G., L.F.G., L.Y.); Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan USA (N.H., R.R., S.S.H., P.M., J.P.K., T.C., E.V., J.E., L.F.G., L.Y.); Center for Molecular Medicine and Genetics, Wayne State University, Detroit, Michigan USA (R.R.); William Beaumont Hospital, Royal Oak, Michigan USA (W.L.); and Case-Metrohealth, Cleveland, Ohio USA (S.A.M.).

Address correspondence to Roberto Romero, MD, Perinatology Research Branch, NICHD/NIH/DHHS, Wayne State University/Hutzel Women’s Hospital, 3990 John R, Box 4, Detroit, MI 48201 USA. e-mail: nichdprbchiefstaff{at}mail.nih.gov

Objective. The objective of this study was to quantify the repeatability and reproducibility of fetal cardiac ventricular volumes obtained using spatiotemporal image correlation (STIC) and Virtual Organ Computer-Aided Analysis (VOCAL; GE Healthcare, Kretztechnik, Zipf, Austria). Methods. A technique was developed to compute ventricular volumes using the subfeature Contour Finder: Trace. Twenty-five normal pregnancies were evaluated for the following: (1) to compare the coefficient of variation (CV) of ventricular volumes obtained using 15° and 30° rotation; (2) to compare the CV between 3 methods of quantifying ventricular volumes: (a) Manual Trace, (b) Inversion Mode, and (c) Contour Finder: Trace; and (3) to determine repeatability by calculating agreement and reliability of ventricular volumes when each STIC was measured twice by 3 observers. Reproducibility was assessed by obtaining 2 STICs from each of 44 normal pregnancies. For each STIC, 2 ventricular volume calculations were performed, and agreement and reliability were evaluated. Additionally, measurement error was examined. Results. (1) Agreement was better with 15° rotation than 30° (15°: 3.6%; 95% confidence interval [CI], 3.0%–4.2%; versus 30°: 7.1%; 95% CI, 5.8%–8.6%; P < .001); (2) ventricular volumes obtained with Contour Finder: Trace had better agreement than those obtained using either Inversion Mode (Contour Finder: Trace: 3.6%; 95% CI, 3.0%–4.2%; versus Inversion Mode: 6.0%; 95% CI, 4.9%–7.2%; P < .001) or Manual Trace (10.5%; 95% CI, 8.7%–12.5%; P < .001); (3) ventricular volumes were repeatable with good agreement and excellent reliability for both intraobserver and interobserver measurements; and (4) ventricular volumes were reproducible with negligible differences in agreement and good reliability. In addition, bias between STIC acquisitions was minimal (<1%; mean percent difference, –0.4%; 95% limits of agreement, –5.4%–5.9%). Conclusions. Fetal echocardiography using STIC and VOCAL allows repeatable and reproducible calculation of ventricular volumes with the subfeature Contour Finder: Trace.

Key Words: cardiac function • Contour Finder • fetal echocardiography • fetus • 4-dimensional ultrasonography • inversion mode, 3-dimensional echocardiography • ultrasonography • ventricular volume

Abbreviations: AV, atrioventricular • CI, confidence interval • CV, coefficient of variation • 4D, 4-dimensional • ICC, intraclass correlation coefficient • STIC, spatiotemporal image correlation • 3D, 3-dimensional • VOCAL, Virtual Organ Computed-Aided Analysis