Techniques et indications de l'IRM du cerveau fœtal

Ultrasound is the first choice modality for the analysis of the fetal brain. Fetal brain abnormalities may have various etiologies: vascular, infectious, genetic and traumatic. MRI is an excellent complementary study for lesions depicted by ultrasound such as: ventricular dilatation, abnormalities of the corpus callosum, white matter destructive lesions and cystic lesions of the posterior fossa. MRI will not only confirm the suspected abnormalities but it will determine their extent and depict associated pathologies. MRI may also be performed for maternal reasons such as obesity or oligoamnios, which render obstetrical ultrasound difficult. Correct interpretation of fetal MRI requires a good knowledge of the fetal anatomy and its evolution during the gestational period. The decision to perform MRI is usually made by a pluridisciplinary team. Following the discovery of any brain abnormalities on fetal MRI, one should search for other malformations such as those of the cardiac, renal and digestive systems. A caroytype may also be performed: all of these associated findings may eventually lead towards the diagnosis of a syndrome or a genetic disorder.