Magnetic resonance imaging of petrous carotid aneurysms.

Aneurysms arising from the petrous segment of the internal carotid artery are rare and the majority of reports are based on evaluations with x-ray catheter angiography (XRA) and computed tomography (CT). Due to the paucity of magnetic resonance imaging (MRI) information, the author describes 2 patients with petrous carotid aneurysms evaluated with MRI and magnetic resonance angiography (MRA). Compared to XRA and CT, MRI and MRA are less invasive and provide more information regarding the aneurysm, including the size, shape, and site; the absence or presence and extent of hemorrhage, thrombus, and bony erosion; patency of the vessel; neck; and the extent of perianeurysmal compromise of vessels, cranial nerves, and parenchyma.