Fetal MRI of the supratentorial brain abnormalities: what we should know about ventriculomegaly?

Fetal MRI is performed to evaluate the brain in cases where an abnormality is detected by ultrasonography (US). Fetal MRI has higher contrast resolution than US. Because the fetal brain is dynamic structure, it is important to know the normal appearance of the brain at different gestational age to be better able to identify abnormalities using MRI. Fast imaging sequences to minimize artifact from fetal motion are required. The main sequences used are ultrafast T2 weighted imaging. Similar to pediatric neuroimaging, images are acquired in the axial, sagittal, and coronal planes. T1 weighted image and Gradient echo-planar T2 weighted images are performed to detect hemorrhage. Ventriculomegaly is the most common central nervous system abnormality identified on US. The causes of ventriculomegaly are very heterogeneous and include developmental, destructive, and obstructive processes, or a combination thereof. MRI improves diagnostic accuracy and can be used to evaluate the etiology of the ventriculomegaly. Moreover, MRI can play an important role in detecting additional findings, which may help to focus on patient counseling and management. This review summarizes and illustrates common pattern of ventriculomegaly due to mainly supratentorial abnormalities.