Which Doppler artifact manifests as a secondary copy of the spectrum on the opposite side of the baseline?

• A. Mirror imaging
• B. Aliasing
• C. Range ambiguity
• D. Spectral broadening

Answer: (A)

Mirror imaging is the Doppler artifact where a second copy of the spectrum appears on the opposite side of the baseline. This happens when a strong reflector or interface reflects the Doppler signal back toward the transducer, creating a ghost image of the flow that mirrors the real spectrum across zero velocity. You’ll see the same waveform on both sides of the baseline, which is what makes it look like a duplicate stream.

Aliasing is different—it’s the wrap of high-velocity information across the Nyquist limit, not a mirrored copy. Range ambiguity involves misplacing echoes along the depth axis due to pulse repetition characteristics, not a mirror across baseline. Spectral broadening refers to the widening of the spectrum due to real terms like turbulent flow or technical factors, not a duplicate spectrum on the other side.