Fetal cardiac circumference derived by spatiotemporal image correlation as a predictor of fetal hemoglobin bart disease at midpregnancy

Abstract

Objectives-The purpose of this study was to evaluate the efficacy of the fetal cardiac circumference derived by spatiotemporal image correlation (STIC) for predicting fetal hemoglobin (Hb) Bart disease. Methods-Pregnancies at risk of fetal Hb Bart disease at 17 to 22 weeks' gestation were enrolled. All underwent STIC volume acquisition for analysis of fetal cardiac dimensions and cordocentesis for Hb level and Hb typing analysis. Spatiotemporal image correlation volume data sets were subsequently analyzed offline for cardiac circumference measurements, which were used to evaluate the efficacy in predicting fetal anemia and fetal Hb Bart disease. Results-A total of 88 pregnancies at risk of fetal Hb Bart disease at 17 to 22 weeks were recruited into the study. The cardiac circumference was significantly higher in fetuses with Hb Bart disease than in unaffected fetuses (1.33 and 1.02 multiples of the median [MoM], respectively; P < .001). The cardiac circumference effectively predicted fetal Hb Bart disease (area under the receiver operating characteristic curve, 0.85; 95% confidence interval [CI], 0.73-0.97), with sensitivity of 86.4% (95% CI, 72.0%-100%) and specificity of 78.1% (95% CI, 68.0%-88.3%) using a cutoff point of greater than 1.17 MoM, whereas the cardiothoracic ratio had better efficacy, with sensitivity of 90.9% (95% CI, 78.9%-100%) and specificity of 85.9% (95% CI, 77.4%-94.5%) using a cutoff point of greater than 0.50. Conclusions-At midpregnancy, a cardiac circumference of greater than 1.17 MoM can be used as an alternative sonographic marker for predicting fetal Hb Bart disease, although not perfectly. However, the cardiothoracic ratio seems to be more accurate than the cardiac circumference for such a purpose. © 2013 by the American Institute of Ultrasound in Medicine.