Most artifacts in radiology refer to something seen on an image that are not present in reality but appear due to a quirk of the modality itself. Artifact is also used to describe findings that are due to things outside the patient that may obscure or distort the image, e.g. clothing, external cardiac monitor leads, body parts of carer, etc.
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 hemosiderin on MRI.
Types of imaging artifacts
- operator technique, e.g. clothing artifact
- 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