Magnetic Resonance Imaging (MRI) of the Spine
An MRI is a test that uses a magnetic field and pulses of radio wave energy to make pictures of the spine. In many cases an MRI gives different information than an X-ray, an ultrasound, or a CT scan. An MRI also may show problems that cannot be seen with other imaging tests.
For an MRI, your body is placed inside a machine that contains a strong magnet. Pictures from an MRI can be saved and stored on a computer for further study. In some cases, a contrast material may be used during the MRI to show certain parts of the body more clearly.
The MRI can find changes in the spine and in other tissues. It also can find problems such as infection or a tumor. MRI can look at the spine in the neck (cervical), upper back (thoracic), or lower back (lumbosacral). The entire spine can be seen in one series of pictures to find a tumor. More detailed pictures of one area, such as the lumbar spine, may be taken.
MRI may be used to check low back problems.
You may be able to have an MRI with an open machine that doesn't enclose your entire body. But open MRI machines aren't available everywhere. The pictures from an open MRI may not be as good as those from a standard MRI machine.
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Why It Is Done
An MRI of the spine is done to:
An MRI may be done using contrast material to see abnormal tissue more clearly. The contrast material also may help tell the difference between old surgical scars and a new disease or injury.
How To Prepare
Before your MRI test, tell your doctor and the MRI technologist if you:
You may be asked to sign a consent form that says you understand the risks of the test and agree to have it done.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
An MRI is usually done by an MRI technologist. The pictures are usually read by a radiologist. But some other types of doctors can also read an MRI scan.
You will need to remove all metal objects (such as hearing aids, dentures, jewelry, watches, and hairpins) from your body, because these objects may be attracted to the powerful magnet used for the test.
You will need to take off all or most of your clothes, depending on which area is examined. (You may be allowed to keep on your underwear if it is not in the way.) You will be given a gown to use during the test. If you are allowed to keep some of your clothes on, you should empty your pockets of any coins and cards (such as credit cards or ATM cards) with scanner strips on them. The MRI magnet may erase the information on the cards.
During the test you usually 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 remain still. The table will slide into the space that contains the magnet. A device called a coil may be placed over or wrapped around the area to be scanned. A belt strap may be used to sense your breathing or heartbeat. This triggers the machine to take the scan at the right time.
If you feel very nervous inside the machine, you may be given a sedative to help you relax. You may be able to have an MRI with an open machine that doesn't enclose your entire body. But open MRI machines aren't available everywhere. The pictures from an open MRI may not be as good as those from a standard MRI machine.
Inside the scanner you will hear a fan and feel air moving. You may also hear tapping or snapping noises as the MRI scans are taken. You may be given earplugs or headphones with music to reduce the noise. It is very important to hold completely still while the scan is being done. You may be asked to hold your breath for short periods of time.
During the test, you may be alone in the scanner room. But the technologist will watch you through a window. You will be able to talk with the technologist through a two-way intercom.
If contrast material is needed, the technologist will put it in an intravenous (IV) line in your arm. The material may be given over 1 to 2 minutes. Then more MRI scans are done.
An MRI usually takes 30 to 60 minutes but can take as long as 2 hours.
How It Feels
You will not have pain from the magnetic field or radio waves used for the MRI. The table you lie on may feel hard, and the room may be cool. You may be tired or sore from lying in one position for a long time.
If a contrast material is used, you may feel some coolness and flushing as it is put into your IV.
In rare cases, you may feel:
There are no known harmful effects from the strong magnetic field used for MRI. But the magnet is very powerful. The magnet may affect pacemakers, artificial limbs, and other medical devices that contain iron. The magnet will stop a watch that is close to the magnet. Any loose metal object has the risk of causing damage or injury if it gets pulled toward the strong magnet.
Metal parts in the eyes can damage the retina. If you may have metal fragments in the eye, an X-ray of the eyes may be done before the MRI. If metal is found, the MRI will not be done.
Iron pigments in tattoos or tattooed eyeliner can cause skin or eye irritation.
An MRI can cause a burn with some medicine patches. Be sure to tell your health professional if you are wearing a patch.
There is a slight risk of an allergic reaction if contrast material is used during the MRI. But most reactions are mild and can be treated using medicine. There also is a slight risk of an infection at the IV site.
The radiologist may discuss some of the results of the MRI with you right after the test. Complete results are usually ready for your doctor in 1 to 2 days.
What Affects the Test
Reasons you may not be able to have the test or why the results may not be helpful include:
Many modern medical devices that do not use electronics—such as heart valves, stents, or clips—can be safely placed in most MRI machines. But some newer MRI machines have stronger magnets. The safety of MRI scans with these stronger MRI magnets in people with medical devices is not known.
What To Think About
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