Fetal Brain Anomalies Associated with Ventriculomegaly or Asymmetry: An MRI-Based Study

BACKGROUND AND PURPOSE:Fetal lateral ventriculomegaly is a relatively common finding with much debate over its clinical significance. The purpose of this study was to examine the association between ventriculomegaly and asymmetry and concomitant CNS findings as seen in fetal brain MR imaging.MATERIALS AND METHODS:Fetal brain MR imaging performed for various indications, including ventriculomegaly, with or without additional ultrasound findings, was assessed for possible inclusion. Two hundred seventy-eight cases found to have at least 1 lateral ventricle with a width of ≥10 mm were included in the study. Ventriculomegaly was considered mild if the measurement was 10–11.9 mm; moderate if, 12–14.9 mm; and severe if, ≥15 mm. Asymmetry was defined as a difference of ≥2 mm between the 2 lateral ventricles. Fetal brain MR imaging findings were classified according to severity by predefined categories.RESULTS:The risk of CNS findings appears to be strongly related to the width of the ventricle (OR, 1.38; 95% CI, 1.08–1.76; P = .009). The prevalence of associated CNS abnormalities was significantly higher (P = .005) in symmetric ventriculomegaly compared with asymmetric ventriculomegaly (38.8% versus 24.2%, respectively, for all CNS abnormalities and 20% versus 7.1%, respectively, for major CNS abnormalities).CONCLUSIONS:In this study, we demonstrate that the rate of minor and major findings increased with each millimeter increase in ventricle width and that the presence of symmetric ventricles in mild and moderate ventriculomegaly was a prognostic indicator for CNS abnormalities.

Fetal lateral ventriculomegaly is a relatively common finding. Some have estimated the incidence of ventriculomegaly identified on sonography to be about 1%.¹ Fetal ventriculomegaly is defined as a dilation of the lateral ventricle atrium to a width of ≥10 mm.^2,3 A measurement of 10–12 mm is commonly referred to as mild ventriculomegaly, while measurements of 12–15 and >15 mm are defined as moderate and severe ventriculomegaly, respectively.⁴ Severe ventriculomegaly has been associated with poorer neurodevelopmental outcome compared with mild ventriculomegaly^5,6; however, it has been previously suggested that the neurodevelopmental outcome in cases of moderate ventriculomegaly is similar to that observed in mild ventriculomegaly.⁷Many studies have focused on the neurodevelopmental outcome of children who were diagnosed in utero with lateral ventriculomegaly.^6,8–16 One of the most important factors determining outcome is the presence and severity of additional CNS anomalies. Although most anomalies can be identified by using sonography, MR imaging was shown to be superior in identifying CNS anomalies. A recent study found that MR imaging could detect additional findings in 15.3% of the seemingly isolated ventriculomegaly/ventricle asymmetry cases.¹⁷ In this study, we aimed to establish the proportion of MR imaging–detected CNS anomalies associated with ventriculomegaly in correlation with the severity of ventriculomegaly and ventricle asymmetry. To prevent underestimation of associated anomalies, we did not exclude cases with CNS anomalies previously identified on sonography. To the best of our knowledge, this is the first large-scale MR imaging study that has examined the association between lateral ventricle width and asymmetry and CNS anomalies.