NMR - spine
Key points
- Magnetic resonance imaging (MRI) of the spine is a noninvasive procedure that uses powerful magnets and radio waves to construct pictures of the vertebral bodies that make up the spine, the spinal cord, and the spaces between the vertebrae through which the nerves travel.
- 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.
- 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 physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust.
Alternative names
Magnetic resonance imaging - spine; Nuclear magnetic resonance - spine; MRI of the spine; Spine MRI
Definition
Magnetic resonance imaging (MRI) of the spine is a noninvasive procedure that uses powerful magnets and radio waves to construct pictures of the vertebral bodies that make up the spine, the spinal cord, and the spaces between the vertebrae through which the nerves travel.
Unlike conventional radiography and CT imaging, which make use of ionizing radiation (X-rays) passing through a patient to generate images, MRI is based on the magnetic properties of atoms. A very small percentage of hydrogen atoms within the body will align with this field. When short radio wave pulses are broadcast toward the aligned hydrogen atoms in tissues of interest, they will return a signal of their own.
MRI scans differentiate between various organs, and potentially, provide contrast between benign and malignant tissue. Any imaging plane, or "slice," can be projected and then stored in a computer or printed on film. MRI can easily be performed through clothing and bones. However, certain types of metal in or around the area of interest can cause significant errors in the reconstructed images (artifact).
How the test is performed
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. If contrast is to be administered, intravenous access will be placed, usually in a small vein of the hand or forearm. 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 to 15 minutes. A complete scan may take up to one hour. Newer scanners with more powerful magnets utilizing updated software and advanced sequences may complete the process in less time.
How to prepare for the test
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
Written and revised by
Gerald Hurowitz, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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