Aliasing of the spectral waveform. Duplex US image shows aliasing of the spectral waveform with wraparound of the highest flow velocities into the negative part of the graph. Note that the color Doppler flow US image shows normal antegrade portal venous flow with no aliasing. To eliminate or reduce this artifact, spectral Doppler US must be active before different parameters can be modified.


http://radiographics.rsna.org/content/24/3/657.figures-only