What artifact displays a series of closely spaced echoes distal to a strong reflector?

The artifact that displays a series of closely spaced echoes distal to a strong reflector is comet tail artifact. This artifact occurs when sound waves encounter a strong reflector, such as a series of closely spaced small structures or material that compresses the ultrasound beam, resulting in multiple returning echoes.

The phenomenon occurs because the ultrasound waves reflect back to the transducer after hitting the dense structures, causing reverberation. As the echoes return, they can create an appearance of a tail that consists of several closely spaced reflections trailing off from the main strong reflector.

Comet tail artifact is common in structures like gallstones or in the presence of other dense materials, where the reflective properties lead to a series of echoes appearing behind the initial strong echo. The closely spaced echoes reflect the time it takes for the ultrasound waves to travel back and forth between the strong reflector and surrounding tissues, contributing to the characteristic "tail" appearance.

Understanding this artifact is crucial for accurate imaging and interpretation, as it can sometimes mimic other conditions or complicate the evaluation of the region of interest if not recognized correctly.