2004 Radiology Exam - Artifacts Case 2

Objective of the Case
1. Recognize artifact
2. identify cause
3. discuss prevention

Information provided to Candidate
Written instructions to:
1. describe the artifact
2. give its cause and
3. describe prevention where applicable

See image below. Click to enlarge.

Findings Expected from Candidate
Identify artifact: Hypoechoic band beyond hyperechoic splenic nodule, due to acoustic shadowing.
Cause: The reduction in amplitude of reflected sound by reflectors that lie beyond strongly attenuating structures, which produce reflection and/or absorption of the sound.
Prevention: None, may be useful in identifying mineral, gas, or fat. Scanning from a different window may allow imaging of shadowed area.

Summary of Overall Candidate Performance
The question was worth a total of 6 points. The average score was 5.25/6.0 or 88%. All candidates easily recognized the artifact, and most were able to discuss cause and prevention. Candidates performing poorly on this case generally had difficulty discussing the physics underlying the cause of this artifact.