Power Doppler Sonography in the Assessment of Cervical Carotid Artery Stenosis.

The assessment of carotid stenosis and plaque morphology is important for the prevention of cerebral infarction. Power Doppler imaging (PDI) is a new non-invasive technique which can visualize intravascular morphology from the integrated power of the reflected echo mainly from red blood cells. We evaluated PDI and color-flow Doppler imaging (CFDI) for the measurement of carotid stenosis and characterization of the plaque surface and compared the results with surgical specimens. PDI is superior for depicting the vessel lumen with intravascular color signals, but has a tendency to underestimate stenosis due to motion artifacts, whereas CFDI overestimates and underestimates stenosis as determined by angiograms. In hypoechoic stenosis such as radiation-induced angiitis, PDI demonstrates the stenotic vascular lumen clearly. Rough and smooth intrastenotic lumina can be compared, and PDI enhances the surface morphology and depicts rough structures, but fails to delineate ulcerative plaque surfaces clearly. CFDI is useful for assessing ulcerative surfaces due to the presence of turbulent flow. These two types of color-coded Doppler sonography complement each other, and increase the reliability of Doppler imaging for noninvasive diagnosis of carotid artery stenosis.