Magnetic resonance imaging (MRI) of the spine is a noninvasive procedure that uses powerful magnets and radio waves to create pictures of the components that make up the spine -- the vertabrae (spine bones), the spinal cord, and the spaces between the vertebrae through which the nerves travel.

Unlike conventional radiography and CT imaging, which uses radiation (X-rays) passing through a patient to generate images, MRI is based on the magnetic properties of atoms.

MRI scans differentiate between organs, and potentially, provide contrast between benign (non-cancerous) and malignant (cancerous) tissue. Any of the images collected can be stored in a computer or printed on film. MRI can easily be performed through clothing and bones. Certain types of metal, however, in or around the area under investigation can cause significant errors, called artifacts, in the images.

Since MRI makes use of radio waves very close in frequency to those of ordinary FM radio stations, the scanner must be located within a specially shielded room to avoid outside interference. The patient will be asked to lie on a narrow table which slides into a large tunnel-like tube within the scanner.

Sometimes an IV is placed in the patient's hand or forearm, to allow contrast medium to be given. A technologist will operate the machine and observe you during the entire study from an adjacent room.

Several sets of images are usually required, each taking from 2-15 minutes. A complete scan may take up to 1 hour. Newer scanners may complete the process in less time.

Because the strong magnetic fields can displace or disrupt the action of implanted metallic objects, people with the following should not be scanned:

• Cardiac pacemakers. People with implanted pacemakers should not enter the MRI area.
• Inner ear (cochlear) implants
• Brain aneurysm clips
• Certain artificial heart valves
• Older vascular stents
• Recently placed artificial joints

Sheet metal workers, or persons with similar potential exposure to small metal fragments, will first be screened for metal shards within the eyes with X-rays of the skull.

The patient will be asked to sign a consent form confirming that none of the above apply before the study will be performed.

A hospital gown may be recommended, or the patient may be allowed to wear clothing without metal fasteners.

Generally there is no pain associated with MRI. Some people are uncomfortable with being inside the scanner and may feel claustrophobic. The table may be hard or cold, but you can request a blanket or pillow. The machine produces loud thumping and humming noises during normal operation. Ear plugs are usually given to the patient to reduce the noise.

A technologist observes the patient during the entire procedure and may be spoken to through an intercom in the scanner. Some MRI scanners are equipped with televisions and special headphones to help time pass during the scan.

Excessive movement can blur MRI images and cause certain image errors. If the patient has difficulty lying still or is very anxious, an oral or intravenous sedative may be given. There is no usually no need for a recovery period, unless sedation was necessary.

After an MRI scan, you can resume normal diet, activity, and medications.

Spine MRI may show the exact location of tumors or other lesions of the spine, spinal cord, or intervertebral disks. It provides detailed pictures of hard-to-view areas of the spine, including the spinal canal, bony segments, and soft tissue. MRI is sometimes used to avoid the dangers of exposure to contrast dye or radiation.

Spine MRI may be performed in a trauma setting to rule out acute compression of the spinal cord in the setting of weakness or paralysis. MRI is also superior to CT in the evaluation of abscesses, tumors, or other masses near the spinal cord. While CT is better at detecting fractures of the vertebrae, MRI can detect subtle changes in the bone which may be due to infection or tumor.