Introduction/purpose Carotid agenesis is a rare congenital anomaly with various compensatory collateralization pathways and associations. The imaging of two patients with true carotid agenesis, one of which was associated with aneurysm formation, were reviewed. Imaging with multiple modalities including CT, MRI, and conventional angiography was obtained.

Materials and methods The electronic medical record and radiologic electronic database were utilized to review patient imaging and obtain relevant de-identified images. Pubmed was utilized to perform a literature review.

Results Multimodality imaging of two patients with true carotid agenesis demonstrates two different collateralization pathways of this rare anomaly. Additionally, the previously described associations of aneurysm formation and dolichoectatic vasculature are demonstrated in one case. Aneurysm treatment in variant intracranial vasculature can provide unique challenges for the neurointerventionalist.

Conclusion Carotid agenesis is a rare condition with multiple subtypes and associations including predisposition to aneurysm formation. We present angiographic and cross-sectional imaging features of true carotid agenesis.

Disclosures C. Green: None. A. Ferrell: None. P. Brown: None. P. Kvamme: None.