Fig. 4

Transcerebellar plane depicting different cerebellar appearances from normal (a) to abnormal (b–d). The latter findings are part of gross intracranial pathology that needs further planes for delineating additional anomalies and establishing the final diagnosis. The rhombencephalosynapsis seen in panel b should necessarily stress an assessment of the ventricular system including the aqueduct of Sylvius (see also Fig. 3). In this particular case, aqueductal stenosis and triventricular enlargement were confirmed. An obstructed CSF pathway resulting in dilated lateral ventricles seen in all diagnostic planes underscored the impression of a Chiari II malformation (panel c). The fetus in panel d had vermian hypoplasia referred to as Dandy-Walker malformation