Artifacts In Medical Imaging
Artifacts are present on many imaging tests. Artifacts do not represent real abnormalities or disease. Artifacts are important because they can be confused for abnormalities and disease.
What are artifacts?
Artifact on an imaging test is something that is seen on an image as abnormal but does not represent a real abnormality.
What causes artifacts?
An artifact may be caused by patient related factors like motion or obesity. There are many artifacts we see from imaging the body. Objects external to the patient like clothing, hair, devices, skin folds, can cause artifacts.
Why is an artifact important?
The reason that artifact is important is that the interpreting radiologist needs to be able to not confuse an artifact for a real abnormality. Sometimes this is not possible and either repeat imaging or additional testing is needed.
What are some common artifacts in imaging?
Patient motion
One of the more common artifacts is related to patient motion. Most imaging exams require you to hold still during the exam and at times hold your breath. Not every patient is able to hold still or control their breath holds. This results in blurry and distorted images which can hide abnormalities.
X-ray artifact example
Some artifacts can mimic life threatening abnormalities. For example, skin folds on chest X-ray can mimic a pneumothorax or collapsed lung.
CT artifact example
Artifacts can mimic clot to the lung or pulmonary embolus on CT scans.
Artifacts can mimic an aortic dissection or tear of the blood vessel on CT scans done for chest pain because of heart motion.
Both experience of the radiologist, modified technique and repeat exams can be done to resolve the uncertainty.
External objects
Some artifacts are related to objects external to the patient. For example, some devices like pacemakers can cause artifacts which block seeing nearby structures.
On a bone X-ray of the hand, a ring can block the view of a portion of the bone if not removed.
On a chest X-ray, hair can overlap the lungs and mimic or hide abnormalities.
Even contrast administered on CT scans can cause artifact near vessels in the chest and limit evaluation of adjacent structures.
Can we always tell an artifact from a real abnormality?
In some cases we can not tell an artifact from a real abnormality. The radiologist may recommend another test or repeat imaging.
Sometimes the artifact will prevent a certain condition from being excluded. An example of this is a CT done to exclude a clot to the lung or pulmonary embolism. When the blood vessels aren’t as bright as they should be or the patient isn’t holding their breath the test can become inadequate to exclude an abnormality. In these cases, you may need a repeat test since this can be life threatening.
Artifacts: summary
Artifacts are frequently seen on imaging tests of all types. These are abnormalities on imaging tests which do not represent disease. These can often be recognized by the radiologist but can at times mimic disease. Repeat or additional testing will often sort the possibilities.
