[Brain MRI: ante and postnatal correlations].

Fetal brain MRI provides complementary information to ultrasonography exploration, the gold standard for antenatal evaluation. Certain specific correlations between the antenatal and postnatal findings merit discussion: cysts after increase in volume during the perinatal period; certain anomalies are at the limit of resolution (tuber of tuberous sclerosis, heterotopy); anatomic visibility of certain structures does not exclude function deficiency (optical chiasma in septo-optic dysplasia; ventricular dilatation is a frequent sign but can occur in very different entities.