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Giant Intracranial Aneurysms with Skull Base Erosion and Extracranial Masses: CT and MR Findings

Objective To present the CT and MR findings of three patients with giant intracranial aneurysms (GIAs), each of which eroded the skull base and had an extracranial mass component. A literature review of GIAs was also performed. Materials and Methods In the past year the imaging studies of three patients with these unusual GIAs were collected at our institutions. All three patients had had CT, and one patient had had MR on a 1.5 T GE unit. Results One patient had a 5 cm GIA in the left petrocavernous region, filling the middle cranial fossa and extending into the left sphenoid sinus and the left posterior ethmoid complex. The aneurysm had heterogeneous high attenuation and extensive rim calcification. The second patient had a 5 cm GIA that filled most of the left middle cranial fossa, eroding the floor and lateral wall and extending into the infratemporal fossa and parapharyngeal space. The aneurysm was partially thrombosed and had minimal rim calcification. The third patient had a 4 cm left cavernous GIA that eroded the floor of the middle cranial fossa and extended into the subjacent parapharyngeal space. The lesion was partially thrombosed and had an enhancing lumen. The rim had low signal intensity on MR. None of these patients had a history of trauma. Conclusion Giant intracranial aneurysms can cause significant skull base erosion and extend into the paranasal sinuses, parapharyngeal space, and infratemporal fossa. The CT and MR findings can lead to an accurate diagnosis.