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Understanding imaging
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MRI or CT — why your doctor chose one
Two cross-sectional scans, two very different ways of seeing. Here is how clinicians decide.
Dr. Elias Marlow
Consultant Radiologist
The short answer
MRI uses a strong magnetic field and radio waves to build detailed images of the inside of the body. It is especially good at showing soft tissue — the brain, spinal cord, ligaments, cartilage and organs.
Because MRI does not use X-rays, it involves no ionising radiation. The trade-off is time: scans take longer than CT and you will need to lie still while the images are taken.
The best scan is the one that answers your clinician’s question with the least burden on you.
What it means for your visit
Preparation depends on the examination. For MRI, the most important things are:
Complete the MRI safety questionnaire before you arrive
Tell us about any implant, pacemaker, stent or metal fragment
Leave jewellery and watches at home
Questions worth asking
What is this examination looking for?
Is there anything I should do — or avoid — beforehand?
How will I receive the results, and who will explain them?
Sample article for template purposes. Replace with content written or reviewed by your clinical team.
Illustrative article for template purposes. Medical content should be written or approved by qualified clinicians before publishing.
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