Fig 3.

A, Unenhanced brain CT scan (axial section) showing a left parieto-occipital hematoma associated with intraventricular hemorrhage in a 19-year-old woman. B and C, Brain CT angiography: axial section (B) and sagittal reconstruction (C). Small false aneurysm arising from the nidus and close to the hematoma is seen on both axial and sagittal images (B and C, white arrows). The close relationship between the intranidal aneurysm and the hematoma suggests the aneurysm as being the cause of the bleeding. D–F, Left vertebral artery DSA in lateral projection at very early phase (D), early phase (E), and intermediate phase (F). At very early phase, opacification of the nidus is seen, supplied mainly by the left posterolateral choroidal artery (D, black arrowheads). Note the opacification of an intranidal aneurysm located at the posterior aspect of the nidus (D, white arrow) before any substantial filling of the venous drainage. At later phase, the origin of the draining vein is filling (E, white arrowheads) while the nidal aneurysm is still visible (E, white arrow). On intermediate phase, stagnation of the nidal aneurysm is seen (F, white arrow) while the venous drainage is more clearly seen (F, white arrowheads).