Positional variations of the common carotid artery bifurcation: implications for digital subtraction angiography.

A retrospective examination of the arteriograms of 200 common carotid artery bifurcations was undertaken to determine the number of instances in which, because of superimposition of the external carotid artery in relation to the internal carotid artery, a lateral view would be required to profile the bifurcation fully. Although oblique views did adequately demonstrate the bifurcation in the majority of instances (124/200, 62%), the lateral view was clearly required for a diagnostically adequate display of the bifurcation in 37% (74/200) of instances. Therefore, if digital radiographs do not profile the bifurcation, a lateral arteriogram should be included in the radiographic examination; some serious, treatable abnormalities will otherwise go undetected.