Duplex sonography of the cerebral arteries: efficacy, limitations, and indications.

This review considers the capabilities and limitations of duplex sonography in the diagnosis of abnormalities of the cerebral vasculature. Duplex sonography is an elegant union of B-mode and Doppler sonography that provides valuable information about atherosclerotic obstruction of the carotid arteries. Duplex sonography also can be used to evaluate, in a general way, the composition of carotid atherosclerotic plaque, and in this respect, it is unique among imaging procedures. Duplex sonography is not very effective in providing a "global" perspective of the cerebral vasculature, because only the cervical portion of the carotid arteries can be examined in detail. The best documented and most clearly effective use of duplex sonography is for detecting severe obstructive lesions in the carotid artery that might warrant endarterectomy in patients with cerebral hemispheric symptoms. The role of duplex sonography in the choice between medical and surgical therapy in asymptomatic patients with carotid artery stenosis is controversial, because the indications for endarterectomy are unclear in these patients. The capacity of duplex sonography to assess plaque composition may ultimately prove to be quite valuable for selecting therapeutic options and for evaluating the effectiveness of medical therapy. Meanwhile, information concerning the clinical value of this use of duplex sonography remains limited.