What is an MRI?

MRI stands for magnetic resonance imaging.

MRI is a way of taking images of the inside of the human body, however unlike traditional X-rays or CAT scans no radiation is used.

An MRI machine consists of a very large and powerful magnet in which the patient lies.

Magnetic signals or fields are sent into the body, and returning signals received to create an image.

MRI is particularly good at looking at soft tissues – brain, spinal cord, nerves, ligaments, joints and muscles.

When would you need an MRI?

Investigation of suspected brain or spinal cord problems, as well as issues including/affecting:

  • Headache
  • Seizures
  • Cerebrovascular accident (CVA or stroke)
  • Multiple sclerosis
  • Weakness
  • Numbness
  • Neck or back pain
  • Joint problems are often investigated with MRI, particualrly problems of the:
  • Spine
  • Knee
  • Shoulder
  • Foot and ankle
  • Wrist

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How is an MRI performed?

The patient usually lies on a narrow table that moves into the MRI scanner. It is important that you lie very still when asked, because movement can cause blurring of the images.

While the magnet works you will hear loud hammering noises. This is quite normal and you do not need to worry.

Sometimes a contrast agent is injected intravenously as part of the study. This improves the clarity of some types of MRI images.

The time taken for an MRI varies depending on the series required. You should ask the staff before the procedure begins.

Are there any side effects of MRI scans?

A number of studies done previously have not shown any known side effects of MRI scans in people who have had them done. The same goes for staff or family that have been present in the room during a scan. Generally, some patients may feel a warm or tingling sensation during the MRI. Though not a side effect, anyone present in the room during an MRI may be given earplugs to minimise the effect of noise from the scanner.

Do metal braces on teeth cause problems with an MRI?

Braces are made from non-magnetic metal so there is no danger to the patient during an MRI scan. However, if the patient is wearing other things like jewelry, they are advised to take everything off so it does not interfere with the imaging. This goes especially if the MRI is for the brain or neck region.

MRI preparation

There are a few important things you need to be aware of before having an MRI.


Some people find being enclosed in the smal space of the MRI scanner for a prolonged period uncomfortable and anxiety inducing. Doctors can give sedation if absolutely required.

Internal metal devices and objects

An MRI involves a powerful magnet and because of this some people with implantable devices should not undergo an MRI.

This includes people with heart pacemakers, cerebral aneurysm clips, inner ear implants or metallic forieign bodies in delicate places such as the eye.

External metal objects

Magnetic objects and objects afected by a magnetic field should be removed before having the scan. This would include watches, credit cards, jewellery, and so on.

MRI results explained

The MRI images are carefully reviewed and reported by a specialist radiologist.

The report is then usually sent to the doctor who requested the investigation a day or two later.

That doctor should go through the results with you, explaining what they mean and what the management plan should be.

Related specialists

Related tests

Also known as

  • MRI
  • Magnetic Resonance Imaging
  • Nuclear Magnetic Resonance Imaging

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This article is for informational purposes only and should not be taken as medical advice. If in doubt, HealthEngine recommends consulting with a registered health practitioner.