MRI Scan: What to Expect

What is an MRI scan?

MRI stands for magnetic resonance imaging.

The scanner uses a powerful magnetic field and radiofrequency signals to create detailed images of structures inside the body.

Different MRI sequences highlight different tissues. This allows radiologists to assess structures such as the brain, spinal cord, muscles, ligaments, joints, abdominal organs, pelvis, heart and blood vessels in considerable detail.

Before your MRI

Your imaging department should tell you whether any special preparation is required.

Depending on the examination, you may be asked to:

• —change into a hospital gown
• —remove jewellery, watches, hearing aids or other metallic objects
• —avoid eating or drinking for a period before the scan
• —arrive early for safety screening
• —have a cannula inserted if intravenous contrast is required.

Before entering the MRI environment, you will normally complete a safety questionnaire.

Tell the MRI team if you:

• —have a pacemaker or implanted cardiac device
• —have any other implanted medical device
• —have clips, metal fragments or other metal within your body
• —have previously had surgery
• —might be pregnant
• —have significant kidney problems
• —have previously reacted to MRI contrast
• —are very anxious about enclosed spaces.

Having metal or an implanted device does not automatically mean that you cannot have an MRI. Many modern devices are MRI-compatible or can be scanned under specific conditions. The MRI team needs accurate information so they can check this safely.

What happens during the scan?

You will lie on a padded scanning table.

Depending on which part of your body is being examined, a specialised piece of equipment called a coil may be positioned around or close to that area.

The table then moves into the MRI scanner.

The radiographer operates the scanner from a nearby control room but can see, hear and communicate with you throughout the examination.

MRI images are collected in groups or “sequences”.

During each sequence you will hear loud knocking, buzzing or tapping noises. You will normally be given ear protection and may be offered headphones.

You need to remain as still as possible while each set of images is acquired because movement can blur the images.

For certain examinations you may also be asked to briefly hold your breath.

How long does an MRI take?

Many MRI examinations take approximately 15–60 minutes, although some specialised examinations take longer.^[1]

The length of the scan depends on:

• —the body part being examined
• —the clinical question
• —how many sequences are required
• —whether contrast is needed
• —whether several different areas need imaging.

It is normal for an MRI to take considerably longer than an X-ray or CT scan.

What if I am claustrophobic?

You are not unusual if you feel anxious about MRI.

Studies of patient experience consistently identify noise, confined space, uncertainty and loss of control as important causes of MRI-related anxiety.^[2]

If you are worried about claustrophobia, contact the imaging department before the day of your scan.

Options vary between hospitals but may include:

• —explaining the procedure in more detail beforehand
• —practising relaxation or breathing techniques
• —using mirrors or other visual aids
• —having reassurance and regular communication from the radiographer
• —using a wider-bore scanner where available
• —medication to help you relax in selected cases.

Research suggests that good information, communication and patient-centred techniques can improve the MRI experience and reduce anxiety.^[2,3,4]

If you require sedating medication, you may need somebody to take you home afterwards and there may be restrictions on driving. Follow the specific instructions given by your hospital.

Will I need contrast?

Not every MRI requires contrast.

For some examinations, a contrast agent containing gadolinium may be injected through a vein to help distinguish tissues or highlight particular abnormalities.

Whether you need contrast depends on the clinical question and the type of scan being performed.

If contrast is planned, the MRI team may ask about:

• —kidney disease
• —pregnancy
• —previous reactions to contrast
• —other relevant medical conditions.

Serious reactions are uncommon, but tell the radiographer immediately if you feel unwell during or after an injection.^[1]

Does an MRI hurt?

The scan itself should not be painful.

Some people find lying still uncomfortable, particularly if they already have back or joint pain.

Tell the radiographer if you are uncomfortable. It may be possible to adjust your position or provide additional support before the scan starts.

What happens after the MRI?

For most routine outpatient examinations, you can leave shortly after the scan.

If you have received contrast, some departments may ask you to remain for a short period afterwards.

If you received sedating medication, different arrangements will apply.

Who looks at my scan?

The images are normally interpreted by a radiologist — a doctor specialising in medical imaging.

The radiologist reviews the images in the context of the clinical question and produces a report for the healthcare professional who requested the examination.

MRI examinations can contain hundreds or sometimes thousands of individual images, and interpreting them properly takes time.

When will I get my results?

The NHS advises that MRI results are commonly available within 1–2 weeks, although this varies considerably depending on urgency, hospital workload and the type of examination.^[1]

Urgent scans may be reported much sooner.

Your referring healthcare professional should explain how and when you will receive your result.

If you have not heard within the timeframe you were given, contact the team that referred you.

Five things to remember

• —Follow the preparation instructions from your own imaging department.
• —Tell the team about implants, devices, previous surgery and possible pregnancy.
• —Tell them before the appointment if you are claustrophobic.
• —Expect loud noises and several periods where you need to remain still.
• —The radiographer performs the examination; a radiologist usually interprets the images.