[What is the impact of fetal magnetic resonance imaging (MRI) on prenatal diagnosis of cerebral anomalies].

Fetal magnetic resonance imaging (MRI) is an adjunct to sonography (US), often necessary when cerebral abnormality is suspected. With use of fast sequences, such as T2 HASTE or SSFSE, gradient-echo T1- weighted images and diffusion-weighted imaging, it is possible to obtain images of fetal brain in three planes without mother's sedation. Diagnosing brain anomalies using MRI requires good knowledge of normal anatomy depending on gestational age: phases of neuronal migration, sulcation and gyration, myelination in particular. The main indications to perform MRI are as follows : ventricular dilatation, midline and posterior fossa abnormalities, microcephaly (in search for migrational disorders), cerebral location of tuberous sclerosis which is suspected when cardiac tumours are detected. MRI allows to confirm US diagnosis and to answer the question whether the abnormality is isolated or complex. This enables not only to establish the diagnosis but also the prognosis. This method plays an important role in the work of the interdisciplinary team managing the pregnancies with a suspicion of congenital anomalies. Prenatal MRI is a great progress in diagnosing brain anomalies and has become indispensable in modern perinatology in the last decades. The situation of mother and child after the anomaly had been detected requires discussion and care of the interdisciplinary team consisting of an obstetrician, neonatologist, radiologist, geneticist, pathologist, psychologist and paediatric neurologist.