Which artifact results in duplication of structures due to interference reflections?

• A. Shadowing
• B. Speckle
• C. Reverberation
• D. Mirror image

Answer: (D)

The main idea being tested is how a strong reflective interface can create a ghost image on the opposite side of that interface in ultrasound. When the beam encounters a powerful reflector (like the diaphragm or other deep interfaces), echoes can travel to the reflector and back to the transducer, but the machine interprets echoes as if they came from a straight path. This misinterpretation places a duplicated structure on the other side of the reflector, creating a mirror-like copy that looks real but isn’t in the actual anatomy. The duplicated image often mirrors the original across the reflective line and can appear with similar brightness.

This differs from shadowing, which is a dark area behind a highly attenuating structure; from speckle, which is random grainy noise inherent to the imaging process; and from reverberation, which produces multiple equally spaced echoes along the same line due to repeated reflections, not a single mirrored copy across a reflector.