Color Doppler artifact from metallic carotid clamp.

The presence of mirror artifacts in color Doppler has been noted by others. In that report, the artifact arose from scattering at the smooth vessel wall and appeared as signal outside the lumen of the vessel, but with no change in flow direction. As experience increases, recognition of the artifacts of color Doppler will lead to a better understanding and more precise evaluation. This case shows that a band of metal around the carotid artery causes registration errors in color-coded Doppler, and perhaps other metal foreign bodies in the soft tissues have similar potential. The specific appearance of the artifact will depend sensitively on the geometrical configuration of the metal body itself and on its orientation relative to the surrounding anatomy and the ultrasound probe. Appropriate placement of the transducer will reduce such artifact.