Artifacts Case

• Identify the artifact or problem
• Describe how the artifact/problem may have occurred
• Discuss how to avoid the artifact/problem or if inevitable, how this would affect interpretation of the study
• Discuss how this particular artifact would affect interpretation of the study.

1. Written instructions above.
2. The candidate was directed to the flame shaped alternating low and high signal intensity artifact distorting the MR image in the region of the pharynx and skin ventral to this area, and asked to address the above written questions regarding this artifact.

• Identify artifact: CT ring artifact
• The artifact is caused by failure of, damage and/or miscalibration of a detector in a 3rd generation CT scanner.
• The candidate was expected to advise that a service visit would be necessary to facilitate identification of the damaged detector and repair of the CT scanner.
• The candidate should relay that the artifact obscures and distorts regional anatomy resulting in this case in a non-diagnostic study, and that ring artifacts if small might mimic pathology.

• The question was worth a total of 6 points. The average score was 5.78/6.0 or 96%.