Congenital anomalies are the second leading cause of perinatal mortality in the United States after premature birth. Advances in imaging techniques have allowed the in utero detection of many anatomical defects with ultrasound. The goal of this project is to improve the diagnosis and treatment of fetal disease and congenital anomalies. The Perinatology Research Branch has initiated a series of projects to improve the detection of congenital anomalies and assess fetal growth and development with the use of three-dimensional ultrasound. The findings of this year include the following: 1. Four-dimensional ultrasonography of the fetal heart using Spatio-Temporal Image Correlation (STIC): The Branch described a new technique for the examination of the fetal heart. Volume datasets of the fetal heart were acquired with a new cardiac gating technique, which uses automated transverse and longitudinal sweeps of the anterior chest wall. These volumes were obtained from 69 fetuses: 35 normal, 16 with congenital anomalies not affecting the cardiovascular system, and 18 with cardiac abnormalities. Dynamic multiplanar slicing and surface rendering of cardiac structures were performed. To illustrate the STIC technique, two representative volumes from a normal fetus were compared with volumes obtained from fetuses with the following congenital heart anomalies: atrioventricular septal defect, tricuspid stenosis, tricuspid atresia, and interrupted inferior vena cava with abnormal venous drainage. Volume datasets obtained with a transverse sweep were used to demonstrate cardiac anatomy. Using a reference dot to navigate the four-chamber view, intra-cardiac structures could be simultaneously studied in three orthogonal planes. Volumes could be interactively manipulated to simultaneously visualize both outflow tracts, in addition to the aortic and ductal arches. Novel views of specific structures were generated. Dynamic multiplanar slicing and surface rendering of the fetal heart are feasible with STIC technology. One good quality volume dataset, obtained from a transverse sweep, can be used to examine the four-chamber view and the outflow tracts. This novel methodology may assist in the evaluation of fetal cardiac anatomy. Moreover, the Branch described the use of color Doppler STIC. Color Doppler STIC allowed multiplanar visualization of ventricular septal defects, multiplanar display and volume rendering of tricuspid regurgitation, volume rendering of the outflow tracts by color and power Doppler ultrasonography (both in a normal case and in a case of a double-inlet right ventricle with a double-outlet right ventricle), and visualization of venous streams at the level of the foramen ovale. This technique has the potential to simplify visualization of the outflow tracts and to improve the evaluation of the location and extent of ventricular septal defects. Other applications include 3-dimensional evaluation of regurgitation jets and venous streams at the level of the foramen ovale. 2. Agreement between observers and reproducibility of a technique to display standard cardiac views of the left and right ventricular outflow tracts from four-dimensional (4D) volume datasets acquired with Spatio-Temporal Image Correlation (STIC): A technique was developed to obtain dynamic multiplanar images of the left ventricular outflow tract (LVOT) and right ventricular outflow tract (RVOT) from volume datasets acquired with STIC. Volume datasets were acquired from fetuses with normal cardiac anatomy. Twenty volume datasets of satisfactory quality were pre-selected by one investigator. The data was randomly assigned for a blinded review by two independent observers with previous experience in fetal echocardiography. Only one volume dataset was used for each fetus. After a training session, the observers obtained standardized cardiac views of the LVOT and RVOT, which were scored on a scale of 1 to 5, based onn diagnostic value and image quality (1 = unacceptable, 2 = marginal, 3 = acceptable, 4 = good, and 5 = excellent). Median scores and interquartile range, as well as interobserver and intraobserver agreement were calculated for each view. Median scores (interquartile range) for LVOT images, obtained by the first and second observers, were 3.5 (2.25-5.00) and 4 (3.00 - 5.00), respectively. The median scores (interquartile range) for RVOT images obtained by the first and second observers were 3 (3.00 - 5.00) and 3 (2.00 - 4.00), respectively. The interobserver intraclass correlation coefficient for the LVOT was 0.693 (95% CI 0.380 - 0.822), and 0.696 (95% CI 0.382 - 0.866) for the RVOT. For the intraobserver agreement analysis, observer 1 gave higher scores to the LVOT the second time the volumes were analyzed [LVOT: 3.50 (2.25 - 5.00) vs. 5.00 (4.00 - 5.00, p=0.008)]. Therefore, STIC can be reproducibly used to evaluate fetal cardiac outflow tracts by independent examiners. Slightly better image quality rating scores during the intraobserver variability trial suggests the need for operator training for the manipulation and analysis of volume data obtained by STIC.
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