1. Four-chamber view and swing technique (FAST) echo: a novel and simple algorithm to visualize standard fetal echocardiographic planes: Novel algorithms using three- and four-dimensional ultrasound have been generated to simplify fetal echocardiography. Using a new display technology (OmniView) for three-dimensional ultrasound, we developed an algorithm using spatiotemporal image correlation (STIC) volume datasets by drawing four dissecting lines through the longitudinal view of the ductal arch. The algorithm was tested in 50 normal fetal hearts between 15.3 and 40 weeks of gestation, and the visualization rates of cardiac diagnostic planes were calculated. The algorithm was also tested in five cases with proven congenital heart defects. In normal cases, the algorithm was able to generate the diagnostic planes individually in 100% of cases (except for the three-vessel view, which was seen in 98%), and simultaneously in 98%. The swing technique was able to generate the three-vessels and trachea view, five-chamber view and/or long-axis view of the aorta, four-chamber view and stomach in 100% of normal cases. In cases of congenital heart defects, the images displayed views that deviated from what was expected from the examination of normal hearts. This study demonstrated that the FAST echo algorithm simplifies examination of the fetal heart, thereby reducing operator dependency. 2. Simple targeted arterial rendering (STAR) technique: a novel and simple method to visualize the fetal cardiac outflow tracts: A major challenge in fetal echocardiography is the visualization of the outflow tracts (aortic and pulmonary arteries). It is now clear that a fetal cardiac examination without adequate imaging of the outflow tracts is incomplete, and may miss major anomalies such as transposition of the great vessels. Imaging of the outflow tracts is operator-dependent and widely accepted to be non-satisfactory. We used OmniView to generate an algorithm which would reliably identify the fetal outflow tracts. Three dissecting lines were drawn through the four-chamber view of the heart contained in a STIC volume dataset. The technique was tested in 50 normal fetal hearts between 15.3 and 40.4 weeks of gestation and abnormal cases. The STAR technique was able to generate the necessary diagnostic planes in all normal cases. In fetuses with congenital heart defects, the STAR technique identified a ventricular septal defect and great vessel anomalies. The practical implication of this work is that physicians can now obtain fetal outflow tract views in most cases when a STIC volume is available. 3. Evaluation of fetal cardiac function with four-dimensional ultrasound using spatiotemporal image correlation (STIC) and virtual organ computer-aided analysis (VOCAL): Evaluation of the basic parameters of cardiac function in the human fetus is challenging and has relied on two-dimensional ultrasound examination, yet this approach relies on many assumptions about the anatomy of the fetal heart which have not yet been validated. Three- and four-dimensional ultrasound allow volumetric examination of the fetal heart, and therefore, determination of key parameters such as stroke output and cardiac volume. We conducted a cross-sectional study in normal pregnancies (19-42 weeks of gestation) to evaluate ventricular volume, stroke volume (SV), cardiac output (CO), and ejection fraction (EF). The CO was also expressed as a function of estimated fetal weight and biometric parameters. One hundred and eighty-four STIC datasets were analyzed. With advancing gestation, ventricular volume, SV, CO, and adjusted CO increased, while EF decreased. The RV volume was larger than the left ventricular (LV) volume in systole (0.50 vs. 0.27 mL) and diastole (1.20 vs. 1.03 mL). There were no differences between the LV and RV in SV, CO, or adjusted CO. LV EF was greater than the RV EF (72.2 vs. 62.4%). This study also provided reference ranges for the evaluation of fetal cardiac performance. 4. Collaborative study on 4-dimensional echocardiography for the diagnosis of fetal heart defects: the COFEHD study: Four-dimensional ultrasound (4DUS) with STIC is used to perform fetal echocardiography, and accumulating evidence indicates that this may facilitate examination of the fetal heart. We conducted a multi-center study to determine the accuracy of 4DUS in the diagnosis of congenital heart defects. Fetuses with and without confirmed heart defects were scanned between 18 and 26 weeks of gestation, and their volume data sets were uploaded onto a centralized file transfer protocol server. Ninety volume data sets were randomly selected for blinded analysis by international experts. Overall, the median (range) sensitivity, specificity, positive and negative predictive values, and false-positive and -negative rates for the identification of fetuses with congenital heart defects were: 93% (77%-100%), 96% (84%-100%), 96% (83%-100%), 93% (79%-100%), 4.8% (2.7%-25%), and 6.8% (5%-22%), respectively. There was excellent intercenter agreement ( = 0.97). This study demonstrates that 4D volume data sets can be remotely acquired and accurately interpreted by experts located at great distances from where patients were examined. These data suggest that tele-fetal echocardiography can be performed around the world.
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