Prenatal diagnosis of a vein of Galen aneurysmal malformation with MR imaging – report of two cases

BACKGROUND Vein of Galen malformations (VGMs) are rare congenital defects of cerebral vessels. They are formed between the 6(th) and 11(th) week of gestation. The background of this defect involves presence of one or more arterovenous fistulas directing bloodflow toward a persistent, dilated, proximal part of median prosencephalic vein (MProsV). Ultrasound examination is a basic test for diagnosis of VGMs. It has now become possible to acquire images of diagnostic value using magnetic resonance (MR) techniques. CASE REPORT This work presents two cases of vein of Galen aneurysms diagnosed prenatally with magnetic resonance imaging. In both patients fetal CNS malformations were diagnosed in ultrasound examinations. MR imaging of the fetal head was performed for further diagnostics. CONCLUSIONS Because of the ability to precisely determine the size of the ventricular system, presence of raised intraventricular pressure and topographic relationships between pathologically changed vessels and particular cerebral structures as well as the presence of ischemic areas MR examination is currently not only complementary to ultrasonography, but is becoming an independent examination method in the diagnostics of vein of Galen malformations.