Malformations of cortical development on fetal MRI

Neuronal migrational anomalies, cortical dysplasias, hemimegalencephaly, and microcephalies are collectively termed malformations of cortical development (MCD). MCDs have multifactorial etiologies including genetic, environmental, vascular, and infectious insults between the late 1^st trimester and late 2^nd trimester. Neonatal correlates of various neuronal migration anomalies detected on fetal magnetic resonance imaging are illustrated. Physiologic immaturity of sulci and certain mimics of migration anomalies can pose a challenge, and these are also outlined.