The role of magnetic resonance imaging in the diagnostic work-up of fetal ventriculomegaly

Abstract

The indication for fetal magnetic resonance imaging (MRI) remains a subject of debate, partly because of questions concerning its diagnostic accuracy compared to ultrasound, partly because of practical factors such as accessibility, high costs and available expertise. Most studies advocate an added value for MRI in cases diagnosed with central nervous system pathology. MRI is a good modality to detect small foci of brain hemorrhage, to depict callosal anomalies, to add information about normal and pathological cortical development, and is a more sensitive imaging method to detect white matter pathology. This manuscript discusses the role of MRI as an adjunct to ultrasound for cases diagnosed-- with cerebral ventriculomegaly.

Keywords: fetal; hydrocephaly; magnetic resonance imaging; ventriculomegaly.

1. T2-weighted axial and coronal images: mild (first column), moderate (middle column) and severe (last column) ventriculomegaly. The atrial diameters and gestational ages are respectively 11, 13 and 24 mm and 29, 27 and 28 weeks.

2. Severe ventriculomegaly, gestational age 24 weeks: small blood remnant adherent to the posterior wall of the occipital horn of the left lateral ventricle, barely detectable on the standard T2-weigthed images (left), but clearly visible as a black spot on the dedicated sequence on the right.

3. T2-weighted images, gestational age 28 weeks: corpus callosum agenesis with colpocephaly in axial (left) and coronal plane (right) with associated interhemispheric cyst.

4. >T2-weighted images, gestational age 23 weeks: ventriculomegaly with cerebellar hypoplasia, agenesis of the vermis and fusion of the cerebellar hemispheres (rhombencephalosynapsis), shown in axial (left) and coronal (right) plane.

5. T2-weighted axial image, gestational age 27 weeks, showing severe ventriculomegaly, megalencephaly (> P97) and polymicrogyria, the latter characterized by the spicular, irregular outlining of the cerebral surface. Tentative diagnosis of MPPH (megalencephaly – perisylvian polymicrogyria - post-axial polydactyly - hydrocephalus) syndrome based on the additional finding of bilateral post-axial polydactyly.

6. T2-weighted axial image (gestational age 30 weeks) in a proven case of congenital Cytomegalyvirus showing borderline ventriculomegaly (atrial diameter 10 mm) and periventricular leucomalacia (marked hyperintense signal of the white matter tissue around the ventricular borders).