Cerebrovascular disease assessed by color-flow and power Doppler ultrasonography. Comparison with digital subtraction angiography in internal carotid artery stenosis.

BACKGROUND AND
PURPOSE: An understanding of carotid atherosclerosis is important to further our knowledge regarding the etiology of cerebral ischemia, and therefore it is necessary to accurately visualize carotid stenosis. The purpose of the present study was to compare different imaging techniques to determine their advantages and disadvantages in the diagnosis and quantification of middle- and high-grade internal carotid artery stenosis. In particular, we were interested in evaluating the effectiveness of the new ultrasound technique power Doppler.
METHODS: Fifty-four patients with greater than 50% extracranial internal carotid artery stenosis, as determined by continuous-wave Doppler, were recruited prospectively to serve as subjects. All subjects were examined with color-flow Doppler, power Doppler, and digital subtraction angiography to enable visualization of carotid stenosis and plaque surface morphology.
RESULTS: Thirty-four middle-grade stenoses (50% to 69%), 32 high-grade stenoses (70% to 99%), and 7 complete occlusions of the internal carotid artery were diagnosed with the use of digital subtraction angiography. Power Doppler visualized stenosis significantly more frequently and accurately than color-flow Doppler. Color-flow Doppler tended to overestimate and underestimate in patients with both middle- and high-grade stenosis. Power Doppler was superior to both color-flow Doppler and angiography with regard to differentiation of plaque surface morphology.
CONCLUSIONS: This study demonstrates that power Doppler is an important, noninvasive imaging technique that has several advantages over color-flow Doppler in diagnosing carotid artery stenosis and visualizing plaque surface. Power Doppler, used in concert with other ultrasound techniques, should enable a more accurate detection and treatment of cerebrovascular disease.