A systematic approach to prenatal diagnosis of transposition of the great arteries using 4-dimensional ultrasonography with spatiotemporal image correlation

Spatiotemporal image correlation (STIC) is a recent technological advance in ultrasonographic imaging that allows dynamic multiplanar slicing and surface rendering of the fetal heart.(1-5) In a previous study, a technique was developed to systematically visualize the outflow tracts from volume data sets acquired with STIC.(3,4) The addition of color and power Doppler imaging to STIC technology made it possible to dynamically display rendered views of the outflow tracts with minimal manipulation of the volume data set.(5) Prenatal diagnosis of transposition of the great arteries (TGA) is associated with a significant reduction in both preoperative and postoperative mortality, a decrease in the rate of metabolic acidosis and multiorgan failure during the neonatal period, reduced need for ventilatory support, and shorter hospitalization time.(6,7) Unfortunately, prenatal detection rates for TGA have been low in most of the studies published to date.(8-15) Among the reasons for failure to prenatally detect most cases of TGA are the absence of risk factors to identify a target population for screening and the need to systematically examine the outflow tracts to establish the diagnosis.(6,16) Despite recommendations; by scientific societies such as the American Institute of Ultrasound in Medicine to extend the basic fetal cardiac examination to include visualization of the outflow tracts whenever technically feasible,(17) this examination remains a technical challenge for many sonographers.(6,18) Four-dimensional volume data set acquisition followed by a systematic approach to image the outflow tracts may reduce the operator dependency of prenatal ultrasonography, Volume acquisition is still operator dependent with current commercially available technology. However, once a good-quality volume data set is acquired, the outflow tracts can be systematically imaged by following algorithms developed for gray scale,(3,4) color, or power Doppler(5) imaging. It is anticipated that algorithms developed to image specific cardiac structures with 3- or 4-dimensional volume data sets may eventually become automated by computer software (automated multiplanar imaging).(19) The objective of this report was to describe the ultrasonographic findings of TGA on the basis of a systematic approach of 4-dimensional echocardiography with STIC.