NMR - lumbosacral spine
Key points
- A lumbosacral spine MRI uses powerful magnets and radio waves to construct pictures of the structures 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.
- Because the strong magnetic fields can displace or disrupt the action of implanted metallic objects, people with cardiac pacemakers cannot be scanned and should not enter the MRI area.
- Some people may experience a claustrophobic feeling from being inside the scanner.
Alternative names
Lumbosacral spine MRI; Magnetic resonance imaging - lumbosacral spine; Nuclear magnetic resonance - lumbosacral spine; MRI of lumbosacral spine
Definition
A lumbosacral spine MRI uses powerful magnets and radio waves to construct pictures of the structures that make up the spine, the spinal cord, and the spaces between the vertebrae through which the nerves travel.
Unlike conventional radiography and Computed Tomographic (CT) imaging, which make use of potentially harmful radiation (X-rays) passing through a patient to generate images, magnetic resonance imaging (MRI) is based on the magnetic properties of atoms.
A powerful magnet generates a magnetic field roughly 10,000 times stronger than the Earth's. A small percentage of hydrogen atoms within the body align with this field. Radio wave pulses are broadcast towards the hydrogen atoms in tissues of interest, returning a signal. The subtle differing characteristics of that signal from different tissues enables MRI to 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.
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 a contrast dye is to be used, it will usually be injected into 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 cardiac pacemakers cannot be scanned and should not enter the MRI area.
MRI also should not be used for people with metallic objects in their bodies such as inner ear (cochlear) implants, brain aneurysm clips, some artificial heart valves, older vascular stents, and 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.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.