Motion artifact
Read Your Scan Editorial Team·Last updated
Written from published radiology references and reviewed for plain language. Not written or signed by a physician, and not a diagnosis. How we write these pages →
In plain language
Blurring or ghosting caused by movement during the scan — breathing, swallowing, a heartbeat, or simply not being able to hold still. It is a fault in the picture, not a finding in you, though a bad enough one can hide something real.
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Where you'll see this
The technique section or a caveat in the impression, on MRI and CT.
Your report may word it “Motion degradation” or “Respiratory motion artifact”. These mean the same thing.
Questions worth asking your doctor
- Was any part of the scan unreadable because of this?
- Does it need to be repeated, and if so how soon?
- Could this have hidden something, or only made the pictures look odd?
How often does this turn up?
Motion artefact is among the most frequently reported technical limitations in imaging, and it is nobody’s fault. MRI in particular builds each image over seconds to minutes, so breathing, swallowing, a tremor, a restless child or simple discomfort all blur the result. Radiologists note it when it affects how confidently they can read the study, which is a statement about the images rather than about the patient.
Does it mean something is wrong?
By itself it is a caveat, not a finding. Its significance is entirely about confidence: mild motion usually degrades the pictures without preventing the question being answered, and the report reads normally with a note attached. Where it is severe, the radiologist will say which structures could not be assessed properly — and that sentence matters, because it means part of the question is still open rather than answered in the negative.
What to do with it
Most reports mentioning motion still reach a conclusion, and nothing further is needed. Where the study was genuinely limited, the options are a repeat scan, sometimes with a faster protocol or with sedation for a child, or a different test that is less sensitive to movement — CT acquires far faster than MRI, which is one reason it is used for people who cannot keep still. If your report says a structure could not be evaluated, it is reasonable to ask whether it needs to be.
Frequently asked questions
- Does motion artefact mean my scan has to be repeated?
- Usually not. Mild motion degrades the images without stopping the radiologist answering the question. A repeat is considered when the report states that specific structures could not be assessed, leaving the original question unanswered.
- Was it my fault?
- No. Scans take time and staying perfectly still is genuinely difficult, especially in pain, and breathing and heartbeat cannot be stopped at all. Departments expect a degree of motion and design their protocols around it.
- How can I reduce motion next time?
- Pain relief beforehand if you are uncomfortable, using the cushions and supports the radiographer offers, and following the breathing instructions closely make the biggest difference. If keeping still is going to be hard, telling the department in advance lets them plan for it.
Picture problems, not body problems
Where this word comes up
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