Neuronal migration and cortical organization takes place primarily during the second trimester and early third trimester. Therefore, detection of cortical malformations and migrational anomalies on a fetal MRI in a maturing brain is difficult and may not be evident in some cases, if performed early. Familiarity with normal sulcation pattern in a fetus at various ages of gestation and a basic understanding of the embryogenesis of neuronal migration is essential to be able to make a diagnosis of these entities. <b>Goals of the exhibit </b> -Understand development of cerebral cortex and normal fetal MRI appearance at various stages of gestation. - Using this knowledge, be able to recognize various cortical malformations in a fetus and provide a comprehensive diagnosis regarding etiology, whenever feasible or when the appearance is typical or when there are ancillary findings - Avoid certain pitfalls and improve accuracy without overcalling or undercalling migrational anomalies in a fetal MRI <b>Outline of the exhibit</b> Embryology of neuronal migration (during second and third trimesters) Normal sulcation pattern during mid and late trimesters Etiology of neuronal migration and cortical malformations -Multifactorial - Infectious - Genetic mutation/chromosomal - Ischemic insult - Metabolic disorders like Zellweger <b>Appearance of various migrational anomalies and cortical malformations in a fetal brain</b> Polymicrogyria – subtle and extensive forms, appearance during various stages of gestation, correlation with post-natal imaging, typical appearance in certain genetic mutations, TORCH infections etc Schizencephaly – associations with absence of septum pellucidum and other abnormalities Gray matter heterotopia – How to differentiate from subependymal nodules and hemorrhage? Lissencephaly – How to identify a true lissencephaly/pachygyria in a developing brain with immature sulcal pattern? Hemimegalencephaly, Microcephaly with simplified gyral pattern and other cortical malformations <b>Evolution of cortical malformations on imaging</b> -Comparison between early and late gestation fetal MRIs in the same patient when available - Prenatal and post-natal MRI correlation of migrational anomalies, when available <b>Ancillary CNS and extra-CNS abnormalities identified in fetuses with migrational anomalies</b> <b>Pitfalls and false positive/ false negative cases and how to avoid them.</b> Read More

Meeting name: SPR 2019 Annual Meeting & Postgraduate Course , 2019

Authors: Ganapathy Shankar, Hunter Kyle, Janitz Emily, Sreedher Gayathri

Keywords: migrational anomalies, cortical malformations