RESUMEN
OBJECTIVE: This study aimed to investigate the application of 3-dimensional computed tomography angiography (3D-CTA) for defining cavernous sinus aneurysms and intradural aneurysms involving the internal carotid artery around the anterior clinoid process. METHODS: Results from 42 patients with an aneurysm of the internal carotid artery around the anterior clinoid process who underwent 3D-CTA were reviewed and compared with those of observed clinical operations. RESULTS: Among the 42 patients, there was a total of 45 aneurysms of the internal carotid artery around the anterior clinoid process. After surgery, 33 of the 45 aneurysms were confirmed as intradural aneurysms, and the other 12 were confirmed as aneurysms in the cavernous sinus. 3D-CTA imaging of the medial sagittal plane showed that 31 out of 31 (100%) intradural aneurysms of the internal carotid artery were above the virtual line between the inferior border of the anterior clinoid process and the tuberculum sellae, and 12 out of 14 (86%) cavernous sinus aneurysms were below the virtual line (P < 0.0001). CONCLUSIONS: The virtual line between the inferior border of the anterior clinoid process and the tuberculum sellae on 3D-CTA indicates the proximal dural ring of the internal carotid artery. This line helps differentiate cavernous sinus aneurysms from intradural aneurysms involving the internal carotid artery around the anterior clinoid process.