Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Vein of Galen aneurysmal malformations are uncommon intracranial anomalies (less than 1–2% of all intracranial vascular malformations) that tend to present dramatically during early childhood, with features of a left-to-right shunt and high-output cardiac failure. The diagnosis is usually made antenatally, generally in the third trimester by ultrasound, which typically shows a dilated anechoic structure in the posterior midline (A, arrow), with prominent flow on Doppler examination (B, arrow). Fetal MRI shows aneurysmal dilatation of vein of Galen, consistent with the diagnosis (C, arrow).