Ring down artifact

Case contributed by Dr Matt A. Morgan

Presentation

Patient presenting for routine liver screening.

Patient Data

Age: 70 years
Gender: Female
Ultrasound

There is both ring down artifact and "dirty shadowing" from the gas in the duodenum. The ring down occurs more centrally in the cluster of gas bubbles with an echogenic step-ladder appearance. The dirty shadowing is on either side of the ring down.

Annotated image

The yellow arrows point to the ring down artifact.

Case Discussion

Gas can cause both "dirty shadowing" or "ring down artifact", depending on the interaction of the sound beam with the gas bubbles.

If the sound beam encounters a tetrahedron of bubbles at the correct orientation, then the reverberation created by this structure creates the classic "stepladder" appearance of ring down artifact.

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