Imaging diagnosis of vascular pathologies of the brain may be potentially misleading if CT Angiography is the only method used. If a patient is clinically stable, catheter-based angiography remains the gold standard for definitive characterization of intracranial vascular pathologies and should be considered prior to any intervention.

From the manuscript

Vascular anomaly at the craniocervical junction presenting with sub arachnoid hemorrhage: Dilemma in Imaging Diagnosis, Endovascular Management and Complications

Abstract
We present a case of a ruptured vertebral artery dissecting aneurysm that mimicked a presumed vascular anomaly by CTA (Computerized Tomographic Angiography). A parenchymal arteriovenous malformation (AVM) or a dural arteriovenous fistula (DAVF) at the craniocervical junction can present with a subarachnoid hemorrhage and cannot be differentiated from a vertebral artery dissection by non invasive imaging. Catheter based cerebral angiography revealed a dissecting pseudoaneurysm of a diminutive right vertebral artery terminating in the posterior inferior cerebellar artery (PICA) that to our knowledge has not been previously reported. NBCA (N-Butyl Cyanoacrylate) embolization of the pseudoaneurysm lumen and sacrifice of the parent vessel resulted in cerebellar infarction, requiring an emergent decompressive craniectomy. The patient recovered to a functional neurologic status.