The bull's-eye sign of extracranial cervical aneurysms.

Overview

Extracranial, cervical aneurysms and arterial thrombosis are uncommon entities. In most cases, they have diagnostic clinical presentations. However, on occasion the history and physical findings do not clearly suggest their presence. In these cases, postcontrast computed tomography scans can aid in rapidly establishing the correct diagnosis by revealing a "bull's-eye" appearance within the mass (vessel lumen). The diagnosis is less difficult to make when the involved vessel is the carotid artery, because this artery is routinely identified on postcontrast computed tomography scans and the lesion can be easily placed along its course. The vascular origin of such a lesion is not usually evident on computed tomography if the process does not lie along the course of a major vessel. In these cases, the bull's-eye sign can establish the diagnosis so that prompt consideration can be given to angiography and therapy.