Which artifact appears as a duplicate of anatomy on the opposite side of a strong reflector?

• A. Mirror image
• B. Grating lobes
• C. Multipath
• D. Noise

Answer: (A)

Mirror image artifact happens when a strong, smooth reflector in the line of ultrasound acts like a mirror. Echoes from structures beyond that reflector are reflected back and received as if they came from the original beam path, so the system displays a duplicate of the anatomy on the opposite side of the reflector. This produces a mirrored copy with similar brightness, often seen across the diaphragm or other prominent reflectors. The result is a convincing second image where there isn’t a second structure, just a reflection of the real one. This differs from other artifacts like grating lobes, multipath, or noise, which don’t create a clean, symmetric mirror across a single reflector.