Using an MRI Scan to Diagnose Spine Pain

Magnetic Resonance Imaging, or an MRI scan, is a relatively new technology. Developed in the 1970s and first put into wide use in the 1980s, MRI technology uses powerful magnetic fields to help physicians image water-containing internal structures of the body, including soft tissues, without surgery. MRI scans are non-invasive and, unlike X-rays or CT scans, are thought to have no potential to significantly damage the body.

While MRI scans are relatively harmless, they are extremely expensive to perform. Therefore, physicians may use them only for specific purposes. Also, MRIs are contraindicated for patients with pacemakers or other implants due to the powerful magnetic field used in the test because the powerful magnetic field may create an electrical current and heat within metallic objects. An MRI scan is useful in diagnosing disc pain and nerve disorders.

Back pain diagnosis via MRI scan

Since MRI scans allow physicians to see and evaluate soft tissue, they are very useful in determining:

  • A narrowed spinal canal or spinal stenosis, which could lead to nerve compression
  • Disc height and hydration, which could indicate the likelihood of degenerative disc disease
  • Herniated discs and bulging discs
  • Alignment of the spine
  • Compressed nerves or sciatica
  • Spinal abnormalities
  • Postsurgical scarring or infection

How MRIs work

MRI machines are essentially gigantic magnets that can encompass an entire human being. Most MRI machines are tube-like, although open-scan MRIs are gaining popularity, since the closed, tube-shaped MRI machines can provoke claustrophobic reactions in some people.

The human body is made up mostly of water molecules. Each water molecule has two hydrogen atoms attached to one oxygen atom. This gives the water molecule polarity, meaning it has a positively and a negatively charged end, or pole. MRI machines generate powerful magnetic fields, which cause the magnetic charges in the body’s water molecules to align along the direction of the field. For example, all positive ends face up and all negative ends face down.

Next, the MRI machine emits an FM radio signal, which causes the water molecules to tip away from their magnetically induced alignment. Once the FM signal stops, the molecules realign themselves to the magnetic field. As they do, they emit their own tiny electrical impulse. The MRI machine detects these impulses and uses them to create a computerized image of the water molecules. Many of the body’s molecules have polarity. The frequencies of the impulse given off by different kinds of molecules differ, depending on the rate at which they realign within the magnetic field. This allows the machine to differentiate between types of tissue present. At the end of the MRI, physicians may have access to thousands of two-dimensional, detailed images of every cubic millimeter of your body. These cross-sectional “slice” images are saved on a computer where they can be used in many ways, including the creation of three-dimensional views of the body.