Fetal face visualization using three-dimensional ultrasonography.

Evaluation of the fetal face is an essential part of the sonographic examination for high risk pregnancies. Even under optimal conditions, the complex curvature of the face makes it difficult to obtain adequate images with two-dimensional ultrasonography, and many cross-sectional images are required to obtain a complete impression. The purpose of this paper is to show preliminary work in assessing the utility of three-dimensional ultrasonographic visualization of the fetal face. Fetal facial features were evaluated with three-dimensional sonography by scanning with a volume transducer and compared to conventional two-dimensional ultrasonographic images in 27 fetuses (gestational ages 10 to 39 weeks). Surface rendered three-dimensional sonographic images of the fetal face were obtained in 24 of 27 fetuses. In four cases the upper lip was clearly imaged on three-dimensional ultrasonography when it could not be seen on two dimensional ultrasonography. Information requiring multiple planes with two-dimensional ultrasonography could be demonstrated on a single image from three-dimensional ultrasonography. Images of abnormal faces were seen with both two- and three-dimensional ultrasonography in two cases of cleft lip and one case of holoprosencephaly. Volume data acquisition required approximately 10 sec and reconstruction required approximately 5 sec with instantaneous review of planes through the volume data set. Surface rendering required 2 to 10 min depending on the angular viewing range. Three-dimensional ultrasonography has the potential to provide improved visualization of the fetal face compared with conventional two-dimensional sonographic imaging.