Magnetic resonance imaging (MRI) is a noninvasive imaging technique. A cervical MRI scans the soft tissues of the neck and cervical spine. The cervical spine is the portion of the spine that runs through the neck.
A cervical spine MRI is used to help diagnose:
- bulging (herniated) discs
- aneurysms (a bulge in an artery)
- other soft tissue disorders
An individual MRI image is called a “slice.” It is an image of a cross-section of tissue, in the same way that a slice of bread is a cross-section of the loaf. One complete MRI scan can comprise hundreds of slices.
An MRI scan uses a powerful magnetic field to take detailed, three-dimensional images of the body.
The human body is 80 percent water. It contains millions of hydrogen atoms. When they come in contact with the MRI’s magnetic field, they all line up in the same direction.
Radio waves produced by the MRI disrupt this alignment. The atoms then return to their original orientation. This takes varying amounts of time, depending on the type of tissue. A sensor in the machine computes these times and the results are translated into images.
In some cases, a contrast dye is injected intravenously before the MRI. This can make it easier to see the details of blood vessels and tumors. An MRI with contrast is called a magnetic resonance angiogram (MRA).
A cervical spine MRI is usually used to diagnose the cause of neck pain. It will be performed if your pain isn’t helped by basic treatment. It will also be used if pain is accompanied by numbness or weakness.
A cervical MRI scan can show:
- spinal birth defects or deformities
- infection in or near the spine
- injury or trauma to the spine
- scoliosis (curvature) of the spine
- cancer or tumors of the spine
A cervical MRI may also be ordered before or after spinal surgery.
To prepare for your cervical MRI, you should:
- Avoid eating or drinking four to six hours before the scan.
- Bring any relevant X-rays, computed tomography (CT) scans, or previous MRI scans.
- Tell your doctor if you have diabetes or kidney problems, if your MRI includes a contrast dye. You may need a kidney function test before the scan. This will ensure that your kidneys can process the dye safely.
- Tell your doctor if you are pregnant. MRIs are not recommended during the first trimester of pregnancy. Your doctor may choose to postpone until after you have delivered. There has been little research into the effects of MRIs during pregnancy.
- Tell your doctor if you are claustrophobic. He or she can prescribe an antianxiety medication. This will help make you more comfortable during the test. If you have an extreme fear of enclosed spaces, you may be given anesthesia to put you to sleep during the test.
- Alert your doctor about any metal implants in your body. It may not be safe for you to have an MRI scan.
- Bring a CD with you. Sometimes, the MRI technician will play music to help you relax.
Before going in for an MRI, you will need to remove all jewelry and clothing that contains metal. It may be easier to leave your jewelry at home. You may need to wear a hospital gown.
If you are obese, you may have trouble fitting into the MRI machine. In this case, your doctor might recommend an “open MRI.” Open MRIs are slightly larger than the standard machines. They can also be used if you are severely claustrophobic. However, open MRIs are not available everywhere.
You will be asked to lie on the narrow bed attached to the MRI machine. Your head will be on a headrest and your arms will be at your sides.
The MRI technician will give you earplugs or headphones to muffle the loud knocking and thumping noises that the machine makes when it is running. Music may also be piped through the headphones. It can relax you and distract from the noise.
A frame called a “coil” will be placed over your head and neck. The coil contains an antenna. It helps focus the machine’s energy to produce the most precise images. The MRI technician will also place a signaling device in your hand. You can use it to summon help while the test is running.
Once you are properly positioned, the table will slide into the machine. The MRI technician will be able to see you through a window in the adjoining room. You will be given periodic updates on the scan’s progress.
Cervical MRI scans take between 30 and 45 minutes. During this time you must hold as still as possible. If you move, the images may be blurred.
MRI scans are very safe. They do not use any form of radiation. The magnetic field and radio waves do not pose any known health risks.
Some people may have an allergic reaction to the contrast dye used during an MRI. Tell your doctor if you have had any prior reaction to injected dyes. Also mention if you have a shellfish allergy.
The magnetic field produced by the MRI scanner is extremely powerful. It will interact with any metal in the room or on or in your body. Tell your doctor if you have:
- an implant, such as a metal plate or screws
- a cardiac pacemaker
- metallic piercings or studs
- an intrauterine device that contains metal
- a drug-delivery device, such as an insulin pump
- aneurysm clips
- a bullet, slug, or shrapnel
- a cochlear implant
- permanent (tattooed) make-up
You may not be able to have a cervical spine MRI if you have metal in your body. If you cannot have a cervical spine MRI, your doctor may order a bone scan or X-rays instead.
Alternative tests may also be used if you are pregnant. There is little known about the effects of an MRI on a developing fetus.