Arteriographic study of patients suspected of having extracranial cerebrovascular disease ideally includes visualization of the carotid, vertebral, and subclavian arteries, from the origin of the aorta to the entrance into the cranial vault. Although it is possible to inject contrast material directly into the carotid and vertebral arteries, or retrograde through the subclavian into the vertebrals, many have chosen to simplify the "four-vessel study" by a single injection into the arch of the aorta, usually through a catheter placed percutaneously via the femoral or brachial artery. However, an arch aortogram made in only one plane may be impossible to interpret because of the tortuosity and superimposition of the many arteries opacified and the study must be repeated in one or more different planes.1 This repeated injection of contrast material necessarily increases both the risk of complications and the discomfort to the patient.2,3 Rotational arch aortography4 is a