Which artifact may appear as multiple reflections between two strong reflectors, creating a series of echoes?

• A. Grating lobes
• B. Mirror image
• C. Reverberation
• D. Shadowing

Answer: (C)

Reverberation artifact is at work here. When the ultrasound pulse gets trapped between two strong reflectors, it bounces back and forth multiple times before returning to the transducer. Each bounce sends out another echo, so you see a chain of echoes along the beam. Because each extra round-trip adds a fixed travel time, the echoes appear at regular, equally spaced depths. The spacing relates to how far apart the two reflectors are and the speed of sound in tissue.

Other artifacts don’t create this train of echoes. Grating lobes produce additional echoes off to the side, not a repeating series along the same beam. Mirror-image artifacts show a ghost image across a strong reflector, rather than multiple echoes along depth. Shadowing is a dark area behind a highly attenuating object, not a sequence of repeated echoes.