MRI Scan: What to Expect and How to Prepare

MRI stands for magnetic resonance imaging. An MRI scanner uses a strong magnetic field and radio waves to build detailed pictures of the inside of your body. It does not use X-rays.

Most MRI scanners are shaped like a short tunnel. You lie on a table that slides into the opening, and the part of your body being examined is positioned in the middle of the scanner. The pictures are taken in sets, and you will be asked to stay as still as you can while each set is recorded.

A radiographer (also called a medical imaging technologist) carries out the scan. A radiologist — a specialist doctor — reads the images afterwards and writes a report for the doctor who referred you.

MRI is particularly good at showing soft tissue. Doctors commonly use it to look at areas such as:

• the brain and spinal cord
• joints, ligaments, tendons and muscles
• the spine and the structures around it
• internal organs, including the liver, uterus and prostate
• the heart and blood vessels

Which scan suits a particular question is a clinical decision. Your doctor may choose MRI, another type of imaging, or a combination — and sometimes a different test is chosen because MRI is not suitable in a person’s circumstances. If you are unsure why this scan was requested, ask the doctor who referred you.

Preparation depends on which part of the body is being scanned and on the clinic’s own protocol, so the instructions you are given when you book are the ones to follow. As a general guide:

• Ask when you book whether you need to fast, and for how long. Some MRI scans require it and many do not.
• Ask whether to take your usual medicines as normal.
• Wear comfortable clothing with no metal — no zips, studs, clips or underwiring. You may still be asked to change into a gown.
• Leave jewellery, watches and piercings at home if you can, rather than bringing them to store in a locker.
• Check whether you should remove make-up, hairspray or nail products; some cosmetics contain metallic particles.
• Allow more time than the scan itself takes — safety screening and paperwork happen first.

Before an MRI you will be asked a set of safety screening questions. The scanner’s magnet is always on, and some implants, devices and metal fragments are affected by it — so this screening decides whether the scan can go ahead safely, and how. Answer it as fully as you can, and tell the clinic when you book rather than waiting until you arrive: some answers change what has to be arranged first.

None of these automatically means you cannot have an MRI. Some do mean the clinic needs details of the device or implant beforehand, and occasionally the referring doctor and the radiologist will decide together that a different type of scan is a better option.

• your referral, if it has not already been sent to the clinic
• your Medicare card, and any concession or DVA card
• private health insurance details, if the scan is being done as a private patient in hospital
• a list of your current medicines
• any previous imaging or reports for the same problem, if you have them and they were done elsewhere
• details of any implant or device you have — a card or documentation is ideal
• your glasses or hearing aids, and someone to drive you home if sedation has been arranged

1. You check in at reception and hand over your referral, along with your Medicare card and any concession card.
2. You complete an MRI safety questionnaire covering implants, devices, previous surgery, allergies and the possibility of pregnancy. Staff will go through it with you.
3. You change into a gown if you have been asked to, and leave metal items, cards and your phone in a locker outside the scan room.
4. The radiographer explains what will happen, how long it should take, and how to contact them during the scan.
5. If contrast is planned, a small cannula (a thin plastic tube) may be placed in a vein in your arm before you go into the scanner.

You lie on the scanner table, usually on your back. A device called a coil may be placed around or near the area being scanned — it helps produce the images and is not uncomfortable. The table then moves into the scanner.

MRI scanners are loud. You will be given earplugs or headphones, and at some clinics you can listen to music. You are given a call button or buzzer so you can reach the radiographer at any point, and the radiographer can see and hear you throughout.

The scan runs as a series of sequences, each lasting from a few seconds to several minutes. Staying still is what keeps the pictures sharp; you may also be asked to hold your breath briefly for some sequences. Some people notice a feeling of warmth. Tell the radiographer straight away if you feel burning, tingling or anything painful.

Scanning time varies a great deal with the body part and the number of sequences needed. Many MRI examinations take somewhere between 15 and 45 minutes, some are shorter, and complex studies can run considerably longer.

Ask the clinic for the expected time for your specific scan when you book, and allow extra for check-in, screening and changing. If you need to arrange parking, transport or time away from work, plan for longer than the scan itself.

The scan itself is not painful — nothing touches you, and you feel nothing from the magnetic field or the radio waves. What people most often find difficult is the noise, and having to lie still in one position for a while.

If contrast is used, you will feel the needle when the cannula goes in, much as you would for a blood test. If lying flat is painful for you, say so before the scan starts — positioning and padding can often be adjusted.

Some MRI scans use a contrast medium — a substance injected into a vein that makes certain tissues, blood vessels or areas of inflammation show up more clearly. The type used in MRI is gadolinium-based. Not every MRI needs it.

Whether contrast is used is decided by the radiologist, based on the clinical question in your referral. That decision is sometimes made during the scan, once the first images have been seen — being told part-way through that contrast is needed does not mean something has been found.

Most people notice nothing from the injection. Some report a cool sensation in the arm, and a small number get a brief headache or feel mildly nauseated. Reactions are uncommon, and imaging practices are equipped and staffed to manage them.

You can ask why contrast has been recommended for your scan, and you can decline it. Declining may mean the images answer less of the clinical question, so it is worth discussing with the staff at the time.

MRI does not use ionising radiation. Ionising radiation is the kind produced by X-ray equipment, including CT scanners, and it is the type associated with a small increase in long-term risk at the doses used in medical imaging. An MRI scanner images the body using a magnetic field and radio waves instead.

That is not the same as saying MRI carries no considerations at all. The magnetic field is the reason safety screening matters, and it is why the questions about implants and metal are asked every time — including on a repeat visit to a clinic that has scanned you before.

Finding the scanner enclosed is common, and staff deal with it routinely. Say so when you book, rather than on the day — there is more that can be arranged with notice.

• Ask what the scanner is like: some scans can be done feet-first, and for some body parts your head stays outside the opening.
• Ask whether a support person can stay in the room with you, once they have been safety screened.
• Ask about eye covers, music or headphones, which help some people considerably.
• Ask the radiographer to tell you how long each sequence will run, so you know what you are counting down.
• Ask whether the clinic has a wider-bore scanner, or can refer you to one.

Medication to help you relax, or sedation, is sometimes an option — but it has to be arranged in advance with your doctor and the imaging provider, and it affects whether you can drive afterwards. It is not something that can be organised when you arrive.

A radiologist reviews your images and writes a report, which goes to the doctor who referred you. Results are not usually given to you at the clinic on the day, and the radiographer performing the scan will not interpret the images for you.

How long the report takes depends on the practice and on how urgent the scan is. Ask the clinic when the report is expected to be sent, then book a follow-up appointment with your referring doctor to go through what it means for you.

Most people go straight back to their usual activities. Nothing is left in your body by the scanner itself, and an MRI does not make you radioactive.

If you had contrast, staff may ask you to wait a short while before leaving so they can check you are comfortable, and to drink normally afterwards. If sedation was arranged, you will need someone to take you home and you should not drive.

Contact your doctor if you feel unwell afterwards, and follow any specific advice the clinic gives you when you leave. If you become seriously unwell, seek urgent medical care — in an emergency, call 000.

In Australia, medical imaging is arranged through a referral (also called a request) from a doctor. You take that referral to an imaging provider, and for most types of imaging you may choose which provider you go to, unless your referral names one.

Whether a Medicare benefit applies to a particular MRI depends on the item, the referral and your circumstances, and MRI has eligibility rules of its own. Because of that, some MRI scans attract a Medicare benefit and some do not.

• Ask the imaging provider what the scan will cost you before you book, and whether they bulk bill it.
• Ask your referring doctor whether the scan they have requested is one that attracts a Medicare benefit.
• Services Australia publishes current information on Medicare and bulk billing, and MBS Online publishes the Medicare Benefits Schedule itself. Both are linked in the sources below.