What ultrasound artifact is a dense tapering trail of echoes just distal to a strong reflector, located parallel to the sound beam and caused by two closely spaced strong reflectors such as calcium, air, or a foreign body?

• A. Comet Tail
• B. Focal Banding
• C. Propagation Speed Error
• D. Ring Down

Answer: (A)

Comet tail artifact is produced when two closely spaced strong reflectors are present, such as calcifications, air, or a foreign body. The echoes bounce between the adjacent interfaces so rapidly that they merge into a dense, tapering trail that extends just distal to the primary reflector and runs parallel to the sound beam. This creates a bright, whisker-like tail behind the reflector. It’s a type of reverberation artifact caused specifically by near-simultaneous reflections, which differentiates it from ring-down (gas-bubble resonance producing a continuous tail) and from other artifacts like propagation-speed errors or focal banding.