Purpose: To illustrate Magnetic Resonance Imaging (MRI) findings of fetal brain in congenital cytomegalovirus infection seen in second and third trimester with postnatal imaging correlation.

Background: Cytomegalovirus (CMV) is an endemic herpesvirus, identified in 0.6 to 0.7% of all live births. CMV spreads to the fetus transplancentally and poses the greatest risk to the developing fetus in the first or second trimester, especially in mothers who acquire a primary infection during pregnancy. Maternal screening for primary CMV infection during pregnancy is not routine in United States, with the onus of diagnosis lying on imaging. Fetal MRI increases the sensitivity and positive predictive value for diagnosis of congenital CMV infection.

Material and Methods:Five consecutive patients with fetal MRI studies obtained during second/third trimesters of pregnancy and postnatal MRI of the brain bearing diagnosis of congenital CMV infection were included in the study.

Results: Fetal and postnatal, brain MRI findings in congenital CMV infection include microcephaly, periventricular calcifications, periventricular cysts (anterior temporal polar- characteristic), intraventricular septae (within occipital horns), cerebellar hypoplasia or dysplasia, cortical migration anomalies, and white matter abnormalities. Of note, the characteristic anterior temporal polar cysts and intraventricular septations are often more pronounced in the fetus compared to older children. 

Conclusions: Fetal MRI increases the sensitivity and positive predictive value for diagnosis of congenital CMV infection and provides important diagnostic and prognostic information. Prenatal diagnosis may impact decisions regarding termination of pregnancy, and initiation of pre- and postnatal antiviral therapy.