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MRI of the Lumbar Spine: About This Test

The back

What is it?

MRI (magnetic resonance imaging) is a test that uses a magnetic field and pulses of radio wave energy to make pictures of the organs and structures inside the body. An MRI can give your doctor information about the spine in your lower back (the lumbar spine). This can include the spine, the space around the spinal cord, and the vertebrae in your lower back.

When you have an MRI, you lie on a table that moves into the MRI machine.

Why is this test done?

An MRI of the lumbar spine can help find the cause of symptoms like back pain or leg pain, weakness, or numbness. It can help find problems such as a herniated disc, a tumour, or an infection.

How can you prepare for the test?

Talk to your doctor about all your health conditions before the test. For example, tell your doctor if:

  • You are allergic to any medicines.
  • You are or might be pregnant.
  • You have a pacemaker, an artificial limb, any metal pins or metal parts in your body, metal heart valves, metal clips in your brain, metal implants in your ears, or any other implanted or prosthetic medical device.
  • You have an intrauterine device (IUD) in place.
  • You get nervous in confined spaces. You may need medicine to help you relax.
  • You wear a patch that contains medicine.
  • You have kidney disease.

What happens before the test?

  • You will remove all metal objects, such as hearing aids, dentures, jewellery, watches, and hairpins.
  • You will take off all or most of your clothes and change into a gown.
  • You may have contrast material (dye) put into your arm through a tube called an IV. Contrast material helps doctors see specific organs, blood vessels, and most tumours.

What happens during the test?

  • You will lie on your back on a table that is part of the MRI scanner. Your head, chest, and arms may be held with straps to help you stay still.
  • The table will slide into the space that contains the magnet.
  • Inside the scanner you will hear a fan and feel air moving. You may hear tapping, thumping, or snapping noises. You may be given earplugs or headphones to reduce the noise.
  • You will be asked to hold still during the scan. You may be asked to hold your breath for short periods.
  • You may be alone in the scanning room, but a technologist will watch you through a window and talk with you during the test.

What else should you know about the test?

  • An MRI does not hurt.
  • You may feel warmth in the area being examined. This is normal.
  • A dye (contrast material) that contains gadolinium may be used in this test. Be sure to tell your doctor if:
    • You are pregnant or think you may be pregnant.
    • You have kidney problems.
    • You've had more than one test that used gadolinium.
  • Health Canada has safety warnings about gadolinium. But for most people, the benefit of its use in this test outweighs the risk.
  • If a dye is used, you may feel a quick sting or pinch and some coolness when the IV is started. The dye may give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache.
  • If you breastfeed and are concerned about whether the dye used in this test is safe, talk to your doctor. Most experts believe that very little dye passes into breast milk and even less is passed on to the baby. But if you prefer, you can store some of your breast milk ahead of time and use it for a day or two after the test.

How long does the test take?

  • The test usually takes 30 to 60 minutes.

What happens after the test?

  • You will probably be able to go home right away, depending on the reason for the test.
  • You can go back to your usual activities right away.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

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Care instructions adapted under license by your healthcare professional. If you have questions about a medical condition or this instruction, always ask your healthcare professional. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.