Role of magnetic resonance imaging in management of congenital cytomegalovirus infection.

Abstract

We congratulate Lipitz et al. on their very interesting paper on the prognosis of fetal cytomegalovirus (CMV) infection in the first trimester of pregnancy1. It is the largest series on this topic, and the information is useful for management of congenital CMV infection. An important point is the risk of sequelae when prenatal ultrasound (US) is considered normal. Lipitz et al. found some cases with severe brain lesions on magnetic resonance imaging (MRI) and normal US. However, these cases are not detailed. In particular, what was the time interval between US and MRI? In our experience, if MRI is performed several weeks after US, it is possible to find anomalies which were not described at US, not because US failed, but simply because the abnormality became visible later. In the two cases with severe (Grade 4–5) MRI findings and normal US that had termination of pregnancy, it is striking that US failed to diagnose periventricular cysts despite the spatial resolution of US being better than that of MRI. Did the authors repeat US after the MRI to determine whether the abnormalities were detectable? Our study that compared US and MRI performed in the same week did not find any added value of MRI2. However, the series of Lipitz et al. is larger and therefore may have picked up rare events. Furthermore, the sensitivity of MRI (as well as US) has increased since we performed our study. MRI and US are two fetal imaging techniques that show different and complementary information. MRI should be used with caution because some findings do not have clinical implications (i.e. Grade 1–2 findings) but can worry parents and clinicians3. The role of MRI in the management of CMV is still to be defined, especially in settings in which MRI is not readily available. As suggested by Lipitz et al.1, and in view of studies which demonstrate that the gestational age at the time of maternal infection is a major prognostic factor4, 5, MRI may be limited to fetuses infected during the first trimester of pregnancy. The delay between US and MRI would have to be taken into consideration in order to compare the two techniques correctly, since it may change the take-home message concerning the usefulness of MRI.