CT with contrast with three reconstructions: sagittal and axial maximum-intensity projection (MIP) and a 3D surface shaded reconstruction. These show an aneurysmal deep venous structure which drains to the vein of Galen, and then to an abnormal falcine sinus. The posterior part of the superior sagittal sinus is enlarged, as are the transverse and sigmoid sinuses. Feeding arteries are multiple, dilated and tortuous. They attach directly to the aneurysm without an intervening nidus.