MR imaging appearance of fetal cerebral ventricular morphology

PURPOSE: To elucidate further the magnetic resonance (MR) imaging appearance of fetal cerebral ventricles by comparing ultrasonographic (US) and MR images. MATERIALS AND METHODS: A retrospective review of MR and US images was performed for 110 normal fetuses and 94 fetuses with central nervous system abnormalities to assess lateral ventricular morphology as having (a) a normal appearance, (b) mild, disproportionate dilatation of the occipital horns with overall preservation of ventricular morphology, (c) colpocephaly with or without normal orientation of the frontal horns, (d) abnormal orientation of the frontal horns without colpocephaly, (e) an angular appearance, (f) fused frontal horns, (g) global dilation, or (h) a distorted appearance. Ventricular morphology on US and MR images was compared and correlated with reference standard diagnoses. RESULTS: US and MR imaging classifications were concordant in 145 of 188 (77%) examinations. Mild disproportion of occipital horns with respect to frontal horns was seen only on MR images. This ventricular configuration was present in eight of 110 normal fetuses and in 10 of 16 fetuses with isolated mild ventriculomegaly (P <.001). An angular configuration of the lateral ventricles, which is seen in fetuses with neural tube defects (NTDs), was present on review of MR images in 11 fetuses and on US images in one fetus. The ventricles of fetuses with NTDs and angular ventricles (3-12 mm) were significantly smaller than those of fetuses with NTDs and global dilatation of the ventricles (13-25 mm; P <.05). CONCLUSION: Ventricular contours differ with differing diagnoses of central nervous system abnormalities. (C) 2002 RSNA.