Introduction Subarachnoid hemorrhage from intradural cerebral aneurysms remains a devastating disease with up to 33% mortality. Hence the point of dural entry of the ICA is of great importance in predicting the risk from a aneurysm in the paraclinoid segment of the ICA. The ophthalmic artery origin has been taken as a surrogate marker for the distal dural ring and subarachnoid space. The anatomy of this region is however complicated by the variable presence of a subarachnoid recess lying below the dural ring and ophthalmic artery termed the carotid cave as described by Kobayashi et al. in 1989. Confusion persists regarding the anatomic structures in this region. Modern high-resolution MRI can now depict the region of the distal dural ring and carotid cave.

Study purpose To demonstrate the presence or absence of a carotid cave and the dural ring in a Middle Eastern population using high resolution MRI. The anatomy of this region will also be discussed.

Materials and methods 25 adult patients referred for brain MRI comprised the cohort and underwent coronal 3D SPACE and time of flight MRA sequences. Images were independently assessed for the visibility of the dural ring and scored for presence or absence of carotid cave. The distal dural ring was identifiable in approximately 92% of individuals. Carotid caves were identifiable in approximately one third of patients consistent with micro-anatomical data.

Conclusion The dural ring and carotid cave can be consistently identified by high resolution MRI. Full results and anatomical review will be presented.

Disclosures D. Jadkareem: None. F. alfadhel: None. J. Bhattacharya: None.