FIG 2. A 55-year-old woman presented with intractable pain and a complete right CN III palsy caused by pressure effect from a giant (25 mm), fusiform, intracavernous internal carotid artery aneurysm. The circle of Willis should be scrutinized as part of the assessment prior to endovascular balloon occlusion of the parent vessel.

A, TOF-MIP MRA (100/20/1) from above and slightly from the right. The right posterior communicating artery (arrow) cannot be differentiated from aneurysm by MIP-MRA findings. The ipsilateral anterior cerebral artery is also poorly demonstrated.

B, TOF-3D-isosurface MRA (100/20/1), similar projection to A. The posterior communicating artery (arrow) can now be clearly separated from aneurysm. The ipsilateral anterior communicating artery is of increased caliber compared with the MIP-MRA projection.

C, TOF-MPR MRA (100/20/1), parasagittal view. The relationship of the posterior communicating artery (arrow) to the aneurysm can be clearly seen along its whole length on this projection. The artery is in contact with aneurysm at its apex.

D, TOF-MPR MRA (100/20/1), coronal view. By scrolling along the posterior communicating artery (arrow) in the coronal plane, its relationship to the aneurysm is clearly depicted.