Imaging description

Giant intracranial aneurysms present unique challenges in diagnosis, characterization, and management. By definition, aneurysms that exceed 25mm in greatest diameter are termed giant aneurysms. Giant aneurysms may be either saccular or fusiform in morphology.

In terms of location, these lesions are most commonly identified in the extradural internal carotid artery (ICA), more specifically in the cavernous segment. Other locations that are involved with some frequency include the middle cerebral artery (MCA) and the vertebral-basilar system. CT is generally the first imaging study obtained, especially in the patients where the initial presentation is with subarachnoid hemorrhage (SAH) or ischemic symptoms. Giant aneurysms are appreciated as round or oval masses that are slightly hyperdense compared to the gray matter (Fig. 8.1). Calcification is a frequent occurrence and can be seen either in the periphery in an “egg shell” fashion or scattered within the thrombosed portion of the lumen. Administration of contrast allows the identification of the patent lumen of the aneurysm.