A coronal T2-weighted image from the MRI of the brain shows a large flow void in the midline posterior to the third ventricle. There is mass effect on the aqueduct resulting in gross dilatation of both the lateral ventricles. MR venography shows aneurysmal dilatation of the vein of Galen.
Galen (born 129 ce, Pergamum, Mysia, Anatolia [now Bergama, Turkey]—died c. 216) was a Greek physician, writer, and philosopher who exercised a dominant influence on medical theory and practice in Europe from the Middle Ages until the mid-17th century.