Duplication images in vascular sonography.

OBJECTIVE

The purpose of this study was to determine the characteristics and phenomena of duplication (or mirror) images in vascular sonography.

METHODS

We retrospectively reviewed 5 cases of vascular sonography that produced duplication images performed between June 30, 2009, and January 10, 2010. The 5 vascular studies included the subclavian artery (2), subclavian vein (1), carotid artery (1), and abdominal aorta (1). The characteristics of the color flow images and spectral Doppler waveforms in the artifactual vessels and in the true vessels were analyzed. Sources and mechanisms of producing duplication images were assessed.

RESULTS

We were able to generate color flows in the artifactual vessels that were the same as in the true vessels in 2 cases. However, we were able to generate images in which the apparent flow directions in the artifactual vessels differed from the actual flow observed in the true vessels in all 5 cases by changing the orientation of the ultrasound beam relative to the true flow and the reflecting surface.

CONCLUSIONS

Duplication images result from mirror reflections producing multipath artifacts. The appearance of the flow in an artifactual vessel on color Doppler imaging strongly depends on the angle of the incident sound beam and the surface structure of the strong reflector relative to the flow in the true vessel. Alternating the scanning plane and the angle of the incident sound beam to the reflector may help distinguish a duplication artifact from a true vessel in ambiguous cases.