Three-dimensional sonographic features of fetal central nervous system anomaly

To visualize an intracranial structure of the fetal central nervous system (CNS) anomaly using transabdominal three-dimensional (3D) sonography.

A total of 12 cases with fetal CNS anomalies (one unilateral ventriculomegaly; three hydrocephalus; three anencephaly; three holoprosencephaly; one Dandy-Walker cyst; and one enlarged cisterna magna) from 17 to 37 weeks of gestation were studied with transabdominal 3D sonography (3.5 MHz).

In unilateral ventriculomegaly, insight view of dilated lateral ventricle, especially dilated atrium was depicted. In hydrocephalus, severely dilated bilateral ventricles and thin brain mantle were very clearly shown. In anencephalus, an absence of the brain and defect of the vault of the skull was clearly noted. In holoprosencephaly, absent interhemispheric fissure, common ventricle, and the extent of thalamic fusion were evident. In Dandy-Walker cyst, cerebellar hemisphere was clearly depicted due to the agenesis of cerebellar vermis. In enlarged cisterna magna, posterior intracranial view of the fetus showed a large space of cisterna magna. Although the diagnosis of each CNS anomaly was made using conventional two-dimensional sonography, 3D sonography proved most helpful delineating the exact nature and anatomic level of the anomaly.

These results suggest that 3D sonography provides a novel means of visualizing fetal CNS anomalies in utero. However, it should be noted that our 3D sonography cannot depict intracranial brain structures in normal fetuses or some CNS anomaly such as intracranial tumor.