A prospective study of fetuses with isolated ventriculomegaly investigated by antenatal sonography and in utero MR imaging

Abstract

Background and purpose: Fetal ventriculomegaly (VM) is important because of its high prevalence and high risk of association with other brain abnormalities. The purpose of this article was to investigate the hypotheses that including in utero MR imaging (iuMR) in the diagnostic pathway for fetuses with isolated VM on antenatal imaging will show other brain abnormalities in a high proportion of cases and that these will have a significant effect on clinical management.

Materials and methods: One hundred forty-seven pregnant women were recruited prospectively from 8 fetomaternal centers in Britain. All of the fetuses had VM diagnosed on sonography but no other abnormality. iuMR was performed, and the results of the examinations were compared with those of sonography. Two fetomaternal experts made independent assessments of the effects of any new diagnoses on clinical management.

Results: Categoric assessments of ventricular size were the same in approximately 90% of fetuses. Other abnormalities were shown in 17% of fetuses. The most frequent additional brain abnormality shown on iuMR was agenesis of the corpus callosum. Severe VM was associated with an approximately 10-fold increase in the risk of another brain abnormality being present when compared with fetuses with mild VM. The most profound effects on clinical management, however, were found in cases of mild VM.

Conclusions: This work supports our hypotheses by showing a high detection rate of other brain pathology when iuMR was used to supplement antenatal sonography (17%). In a high proportion of cases, the detection of the extra pathology would have led to significant changes in clinical management.

Fig 1.

In utero MR imaging (iuMR) scans of a fetus at 23 weeks’ gestational age thought to have isolated ventriculomegaly (VM) on sonography. A and B, Axial (A) and a montage of 4 consecutive coronal single-shot fast spin-echo images (B) show agenesis of the corpus callosum with colpocephaly.

Fig 2.

A fetus depicted on iuMR at 30 weeks’ gestational age because of VM. A and B, Axial (A) and a montage of 4 consecutive coronal single-shot fast spin-echo images (B) show agenesis of the corpus callosum with colpocephaly.

Fig 3.

iuMR images of a fetus at 31 weeks’ gestational age thought to have isolated VM on sonography. Axial (A) and a montage of 4 consecutive coronal single-shot fast spin-echo images (B) show agenesis of the corpus callosum and an associated interhemispheric cyst. The cortex adjacent to the cyst was interpreted as abnormal, but no formal confirmation of that finding is now available.