Artifact

Artifacts in radiology refer to something seen on an image that is not present in reality but appears due to a quirk of the modality itself.

The commonest artifact seen in radiology is image noise, which is inherent to every modality and technique, and can be mitigated but never eliminated.

As an interpreter of imaging it is important to be aware of the main artifacts of the examination being reviewed to avoid issuing an erroneous report. However at times artifacts are intentional because they may be advantageous to the interpreter, making anatomy/pathology easier to appreciate, e.g. posterior acoustic shadowing of gallstones on ultrasound or susceptibility artefact of haemosiderin on MRI.

Types of imaging artifacts

• operator technique, e.g. clothing artefact
• instrumentation, e.g. ring artifact in CT
• technique, e.g. magic angle effect on MRI
• patient factors, e.g. respiratory motion
• image processing, e.g. stair step artifacts on CT

Artifacts by modality

• x-ray artifacts
• nuclear medicine artifacts
  • PET artifacts
• ultrasound artifacts
• CT artifacts
• MRI artifacts