Accuracy of three-dimensional gadolinium-enhanced MR angiography in the assessment of extracranial carotid artery disease

OBJECTIVE. The purpose of this study was to assess three-dimensional (3D) gadolinium-enhanced MR angiography, used alone or in association with duplex Doppler sonography, with a fast acquisition time (8 sec) for evaluating the extracranial carotid arteries. SUBJECTS AND METHODS. In this prospective study, 48 successive patients with carotid artery stenoses were examined with 3D gadolinium-enhanced MR angiography and 3D time-of-flight MR angiography. Of the 44 eligible patients, conventional angiography was available in 33 and duplex sonography in 27. We used the North American Symptomatic Carotid Endarterectomy Trial technique to quantify stenosis on all angiograms, and a 250 cm/sec threshold at duplex sonography to diagnose stenoses greater than 70%. Image quality of 3D gadolinium-enhanced MR angiography and 3D time-of-flight MR angiography was assessed, as well as sensitivity and specificity for each technique alone and in combination with duplex sonography. Conventional angiography was the gold standard. RESULTS. Three-dimensional gadolinium-enhanced MR angiography yielded good image quality in 90% of cases. When used alone, it yielded a sensitivity and a specificity of 94% and 85%, respectively, in screening stenoses greater than 70% (70-99%). When combined with duplex Doppler sonography, it provided a 100% sensitivity and specificity for detection of stenoses between 70% and 99% and would have obviated 61% of conventional angiography. In comparison, 3D time-of-flight MR angiography used alone yielded a sensitivity of 88% and a specificity of 94%. In combination with duplex Doppler sonography, its use would have obviated conventional angiography in 74% of cases. Three-dimensional gadolinium-enhanced MR angiography provided accurate results in the diagnosis of occlusions and ulcers and can visualize distant stenoses. CONCLUSION. Used alone, 3D gadolinium-enhanced MR angiography is not accurate enough to replace conventional angiography in the evaluation of extracranial carotid arteries. In association with duplex Doppler sonography, however, it is accurate and may obviate a significant number of conventional angiographic examinations.