Left brachiocephalic vein vascular ring on CT: A rare venous anomaly

We present a case of a vascular ring formed by the left brachiocephalic vein. A left brachiocephalic vein ring or circum-aortic left brachiocephalic vein is a rare congenital vascular variant. Although it is usually an incidental finding on chest imaging studies, left brachiocephalic vein anomalies, particularly the ring variant, can be clinically significant during procedures requiring installation of transvenous implantable devices such as pacemakers. In this report, we illustrate the appearance on computed tomography of this rare anomaly and discuss an embryological hypothesis for the etiology.