Four-dimensional Ultrasonography Of The Fetal Heart With Spatio-temporal Image Correlation

ObjectiveSpatio-temporal image correlation (STIC) is a new four-dimensional (4D) technique allowing the acquisition of a volume of data from the fetal heart that is displayed as a cineloop of a single cardiac cycle. The aim of the study was to examine whether the multiplanar display of STIC volume could produce most of the standard image planes necessary for a comprehensive diagnosis of congenital heart deseases (CHD); to describe a method of 4-dimensional reconstruction of the cardiac septae, valves, chambers and outflow tracts using a combination of STIC, surface mode, inversion mode ,color mode and B-flow imaging; to assess whether STIC acquisition technique can be taught to general obstetricians by e-mail, whether STIC volume datasets can be transmitted over the Internet, and whether STIC volume datasets analyzed offline at a remote setting(TELE-STIC) can be used to confirm or exclude major cardiac defects.MethodsThe acquisition was performed in two steps:first,images were acquired by a single,automatic volume sweep, second, the system analyzed the image data according to their spatial and temporal domain and processed an on line dynamic 4D image sequence that was displayed in a multiplanar reformatted cross-sectional display and/or rendered display.STIC cardiac images of 138 normal fetuses and 52 CHD fetuses were collected using grey-scale 2-dimensional imaging technique and color Doppler imaging technique, and were displayed and analyzed in multiplanar reformatted cross-sectional display.STIC cardiac images of 160 normal fetuses and 56 CHD fetuses were obtained using grey-scale 2-dimensional imaging technique,color Doppler imaging technique and B-flow technique, respectively. Under the guidance of cross-sectional display, images collected with grey-scale 2-dimensional imaging technique were reconstructed using surface mode and inversion mode; images collected with B-flow technique were reconstructed using surface mode and images collected with color Doppler imaging technique were reconstructed using color mode and glassy body mode.47 pregnant women were selected by two general obstetricians (operators A and B). Both obstetricians lacked skill in the performance of fetal cardiac examination. The acquisition skill of STIC was taught by e-mail.The acquired volume datasets were uploaded using an Internet broadband connection. Offline analysis was performed by a single investigator experienced in fetal echocardiography (the administrator C).ResultsSTIC volume data sets were achieved using two different imaging modalities in 138 normal and 52 CHD fetuses, with 231 and 98 qualified volume images, respectively. Displaying rate of cardiac structures or views in normal and CHD fetuses using gray-scale 2-dimensional technique were 91.7%, 71.3%, respectively. Using color Doppler imaging technique, displaying rate of cardiac structures or views in normal and CHD fetuses were 95.9%, 74.9%, respectively.All the volume images of 160 normal and 56 CHD fetuses collected using three different imaging modalities were reconstructed successfully. The atria-ventricular valves, intracardiac demonstration of interventricular or interatrial septae, cardiac coronal view at base level that showed in reconstructed images could not be observed using 2-dimensional technique, otherwise, 3 to 4 pulmonary veins could not be seen simultaneously in 2-dimensional images.A telemedicine link via the Internet was possible in all cases. Seventy-four volume datasets were sent to the web server. A complete cardiac examination according to set criteria was achieved by the administrator in 88.3% of the cases scanned by one operator and 81.8% by the other operator. Two fetuses had cardiac defects confirmed postnatally, one fetus had extracardiac anomalies and two fetuses had suspected cardiac defects ruled out by TELE - STIC.ConclusionsVolume imaging collection, cross-sectional display and analysis of fetal heart are feasible using grey-scale 2-dimensional technique and color Doppler imaging technique combination with STIC. This novel method may assist in the prenatal diagnosis of congenital heart disease, and can provide more structure information that the 2-dimensioanl imaging can not obtain.4-dimensional reconstructions of fetal heart using different imaging modalities combination with STIC are feasible. This new method can provide more morphologic information, and make inter-team communication and parents counseling more convenient.STIC volumes can be obtained by operators inexperienced in fetal echocardiography, transmitted via the Internet, and their analysis enables recognition of most of the structures and views necessary to assess fetal cardiac anatomy. The preliminary use of TELE-STIC allowed us to demonstrate that some intracardiac anomalies can be ruled out and others confirmed.