MRI Scan

What is an MRI scan?

A magnetic resonance imaging (MRI) scan takes detailed pictures of the inside of your body. It can show problems without the need for surgery. It can also be useful for planning treatments for injuries and illnesses.

An MRI scanner is often shaped like a tunnel, with a table for a person to lie on that slides through the middle. The scanner uses strong magnetic fields and radio waves to generate signals from the body. These are picked up by a radio antenna and processed by a computer to create detailed pictures.

The benefits of an MRI are that it produces very detailed pictures, does not use x-ray radiation, and is painless.

When is an MRI scan used?

An MRI is used to show certain problems, such as an injury, or in combination with other tests to diagnose a condition.

An MRI scan can be used to examine the:

MRI is generally used for investigation, diagnosis and planning of treatment of:

Is an MRI safe?

An MRI is a very safe procedure, but there are some things you should consider before the scan.

You must lie still in a small space, which some people find hard. It can last as little as 10 minutes, but most are longer. An MRI scan can last as long as 2 hours or more.

If you are afraid of small or tight spaces, make sure you tell the doctor first. You may be able to have medicines to keep you calm during the scan. Sometimes you will be able to take a CD or DVD into the scan with you to keep your mind busy. Young children and babies may need a general anaesthetic to keep them still.

Is an MRI scan right for me?

Some people cannot have an MRI, for example, people with a pacemaker or certain implants. This is because metal interacts with the magnet and can cause serious harm to the patient.

Make sure you tell the doctor who orders the scan and also the radiology practice if you have a:

You should also tell your doctor and the radiology practice if you have:

If you have one of these, you may still be able to have an MRI scan. Sometimes your doctor will need to order a different type of scan.

Make sure you do not wear any make up or hairspray when you have your MRI scan, as these may contain tiny metal particles that may interfere with the scan, heat up or even burn you.

Having an MRI is thought to be safe in pregnancy, but not in early pregnancy, so discuss your situation with your doctor.

MRI scan procedure

Generally, an MRI involves the following:

You will be asked to remove all metal objects, including wristwatches, keys and jewellery. These items must be left outside the scan room.
In most cases, you are asked to undress and put on a cotton gown.
You are instructed to lie on the scanner’s table. The table then slides into the cylinder. An intercom inside the MRI scanner allows you to talk with the radiography staff.
It is important to lie very still. Movement will blur or distort the pictures.
While it is in operation, the MRI scanner makes noises such as knocks, loud bangs and clicks. (You may be offered earplugs. In some cases, you can listen to music through headphones if you prefer
While it is in operation, the MRI scanner makes noises such as knocks, loud bangs and clicks. (You may be offered earplugs. In some cases, you can listen to music through headphones if you prefer.
The scanned area of your body may feel a little warm.
The scan may take up to an hour, depending on the nature of the investigation.

Immediately after the MRI

You may be asked to wait while the radiographer checks the quality of the pictures. In some cases, you may be asked to get back into the MRI scanner so that more pictures can be taken. If the pictures are satisfactory, you can get dressed and go home.

There are no known long-term side effects from undergoing MRI. The MRI scan does not use ionising radiation to achieve its pictures. The MRI scan is a non-invasive, painless and safe procedure that doesn’t require any ‘recovery time’. Be guided by your doctor but, generally, there are no special after-care instructions. A radiologist and other specialised doctors will examine and interpret the scan images. A report of the radiologist’s findings is sent to your doctor. You will need to make an appointment with your doctor to discuss the results. The MRI scan will help the doctor to plan appropriate treatment, if necessary.

Complications of an MRI

The MRI scan is a very safe procedure. Occasional complications may include:

Metal objects (such as jewellery) worn during the scan can cause injury.
The powerful magnetic field of the MRI scanner may damage internal metal devices, such as a heart pacemaker.
In some cases, such as in the investigation of blood vessels, a contrast dye is injected into a vein immediately prior to the scan. This helps to produce a clearer picture. Rarely, a patient may have an allergic reaction to the contrast dye.