Figure 5

Stenotic ICA Images and Waveforms. A. Systolic velocity > 1.25 m/s is consistent with an angiographic stenosis > 50% diameter reduction (DR). Both the PSV = 2.69 m/s and the EAV = 1.78 m/s exceed the criterion. Color aliasing (cyan/blue) can be seen at the stenosis location, although the color aliasing velocity of 0.29 m/s, when adjusted for Doppler angle of 60 degrees (0.58 m/s) and for estimated aliasing magnitude (1.16 m/s), suggests that the color image was captured in diastole, at the right edge of the waveform. B. EDV > 1.4 m/s is consistent with a severe angiographic stenosis > 80% DR. A magnified view of the color flow lumen image appears to reveal no hemodynamic stenosis. The apparent filling of an extra-luminal space with color is sometimes due to specular (mirror-like) reflection of ultrasound from the deep luminal surface. If the extravascular tissue is echogenic, write priority will suppress the Doppler color, but if the extravascular tissue is anechoic, Doppler color remains in that portion of the image. The dark (anechoic) region between the color flow lumen and the brighter arterial wall deep to the Doppler color would be interpreted by some as plaque burden.