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US of Neurovascular Occlusive Disease: Interpretive Pearls and Pitfalls¹

¹ From the Departments of Radiology (J.M.R., M.H.L., M.M.C., R.C.C., A.E.J., R.G.G., R.H.A.) and Neurology (R.H.A.), Massachusetts General Hospital and Harvard Medical School, 55 Fruit St, Boston, MA 02114; and the Department of Optometry and Radiography, Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong (S.T.C.). Presented as an education exhibit at the 2001 RSNA scientific assembly. Received January 21, 2002; revision requested March 6 and received April 1; accepted April 1. Address correspondence to M.H.L. (e-mail: mlev@partners.org).

Ultrasonography (US) of the head and neck is a convenient but operator-dependent screening tool for detection and diagnosis of neurovascular occlusive disease. In US examination of the extracranial carotid arteries, stenosis is most commonly graded according to the peak systolic Doppler velocity in the region of maximal luminal narrowing rather than according to the percentage of atheromatous plaque occupying the lumen. However, the peak systolic velocity is not always reliable in estimation of the degree of stenosis. General diagnostic pitfalls include technical difficulties with scanning, failure to review the spectral waveform patterns, the presence of additional stenotic lesions, and anatomic variants. Specific examples of pitfalls include tandem lesions, differentiation of pseudo-occlusion from true total occlusion, pseudonormalization of velocities in cases of very severe stenosis, lesions of the carotid artery origin or aortic valve, progression of subclavian steal, underestimation of severe stenosis due to heavily calcified plaque, a persistent trigeminal artery, and contralateral carotid artery stenosis. Although conventional angiography remains the standard of reference for assessment of carotid artery disease, recognition of these common sources of error in US can improve the accuracy of this noninvasive test in diagnosis of carotid artery occlusion.

© RSNA, 2002

Index Terms: Carotid arteries, stenosis or obstruction, 172.721, 904.721 • Carotid arteries, US, 172.1298, 904.1298 • Subclavian steal syndrome, 901.767 • Ultrasound (US), Doppler studies, 172.12984, 90.12984 • Vertebral arteries, US, 901.1298

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