Fetal Magnetic Resonance Imaging in Holoprosencephaly, Agenesis of Corpus Callosum and Chiari II Malformation

Abstract

We describe our experience based on 177 fetal MRI examinations performed in the last ten years, focusing on fetal brain anatomy and fetal brain anomalies, namely oloprosencephaly, agenesis of corpus callosum and Chiari II malformation. Magnetic resonance imaging (MRI) has been proposed as an alternative technique when an expert sonologist requires an in-depth morphological approach. However, there were few literature reports in the 1980s and early 1990s because of both the invasive technique of fetal curarization and later the technical difficulties of MRI “breath holding” sequences. Interest in fetal MRI increased in the late 1990s and many papers appeared after the introduction of MRI ultrafast sequences. Ultrasonography remains the first choice for investigation in pregnancy and technological progress in this diagnostic area with overall 3D ultrasound imaging has led to more accurate indications for fetal MRI in cerebral malformations. The main contribution of fetal MRI imaging is a clear “educational” demonstration of classic malformative patterns of the major pathologies, thanks to spectacular images. We conclude that fetal MRI examination is impressive but substantially unnecessary in the three malformative pathologies considered and in all major malformations. Current use of fetal brain MRI should be reserved for more subtle malformations like neuronal migration disorders, ventriculomegaly of the early second trimester of pregnancy and similar conditions where ultrasound is still ineffective.