Cytomegalovirus-related fetal brain lesions: comparison between targeted ultrasound examination and magnetic...

To evaluate the relative contributions to the diagnosis of fetal brain abnormalities of targeted ultrasound examination and magnetic resonance imaging (MRI) in fetuses infected with cytomegalovirus (CMV).

This was a retrospective analysis of targeted brain ultrasound examination and fetal brain MRI performed in fetuses diagnosed with CMV infection following proven maternal primary infection. The prenatal findings were compared with findings from postnatal transfontanellar ultrasound examination during the first week following delivery or from postmortem when the pregnancy was terminated.

Both targeted prenatal ultrasound and MRI were performed on 49 fetuses. Brain abnormalities were present in 15/49 (30.6%) cases at postnatal/post-mortem follow-up. Fetal cerebral abnormalities were observed in 19/49 (38.8%) cases by ultrasound and/or MRI. The most frequent cerebral lesions induced by CMV and seen on ultrasound and MRI, respectively, included ventricular dilatation in nine and five cases, subependymal cysts in two cases each, microcephaly in five and three cases and periventricular calcifications in five cases on ultrasound only. Termination of pregnancy was performed in 10/49 cases. Sensitivity, specificity and positive and negative predictive values for the presence of cerebral lesions were 88.9%, 93.3%, 88.9% and 93.3%, respectively, when both prenatal ultrasound and MRI findings were abnormal, 85.7%, 85.3%, 70.6% and 93.5%, respectively, for ultrasound alone, and 42.9%, 91.2%, 66.7% and 79.5%, respectively, for MRI alone. Prenatal ultrasound, MRI and postnatal or postmortem examinations were concordant with the presence of brain abnormalities in six cases; however, their conclusions were exactly concordant in only two (33.3%) of these cases. In cases without cerebral abnormality, the results of prenatal and postnatal/postmortem examinations were concordant in 28/34 cases.

The addition of MRI to ultrasound increases the positive predictive value for the diagnosis of fetal brain abnormalities in fetuses with CMV. The two techniques appear to be complementary and should not be mutually exclusive in high-risk fetuses. Their high predictive value for the presence or absence of cerebral lesions provides a useful tool for appropriate counseling since current evaluation of the prognosis is based mainly on the presence of fetal brain lesions. The lack of concordance between ultrasound and MRI should stimulate standardization of the interpretation of both ultrasound and MRI prospectively.