Three-dimensional and four-dimensional fetal echocardiography: a new frontier

One of the difficulties of conventional two-dimensional cardiac imaging is the inability to examine fetal cardiac anatomy from multiple angle planes. Three-dimensional and four-dimensional ultrasound allows the fetal examiner to more accurately accomplish this task. Currently, multiple disciplines may be involved in the examination of the fetal heart (pediatric cardiologists, obstetricians, maternal-fetal medicine specialists, and radiologists). The three-dimensional and four-dimensional imaging equipment used by these specialty physicians varies greatly. The purpose of this communication is to review techniques using three-dimensional and four-dimensional imaging that the pediatric cardiologist may not be exposed to in the clinical environment, however, in consulting with colleagues needs to have an understanding of these imaging modalities.

The reconstruction of cardiac structures using this technology allows the examiner to view cardiac anatomy in a manner that was limited by previous two-dimensional imaging. Volume datasets are obtained in the three-dimensional static mode (no cardiac motion) or using four-dimensional - the three-dimensional heart is observed contracting during one or multiple cardiac cycles. Therefore, the fourth dimension is time. Using either three-dimensional or four-dimensional technology datasets are acquired, followed by image reconstruction. The image reconstruction enables the examiner to evaluate a two-dimensional image using multiple views, evaluate intracardiac anatomy at different depth planes, and recreate casts of blood flow of the chambers and great vessels.

This new technology has enhanced the ability of the examiner to identify normal and complex fetal heart anatomy during the early second to the late third trimesters of pregnancy.