Prenatal imaging of congenital malformations of the brain.

This article represents an overview of ultrasound (US) and magnetic resonance imaging (MRI) of the normal fetal brain during the second and third trimesters, followed by the description of congenital pathologic conditions. Fetal imaging of the brain requires an understanding of embryology that defines the normal anatomy of the brain at each gestational age. Without knowledge of the normal developmental milestones, it is impossible to accurately diagnose prenatal central nervous system (CNS) disorders. In the first section, a brief review of the normal anatomy and milestones by using US and fetal MRI will be described. The second part will provide a summary of congenital malformations with respect to embryologic event and their typical imaging patterns on prenatal US and MRI.