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MRI - A POWERFUL DIAGNOSTIC TOOL
from Better Health magazine, Spring, 2000
MRI (magnetic resonance imaging) has become an important diagnostic tool for doctors. Staff radiologist Ronald L. Washburn, M.D., helps explain how MRI works and what patients can expect from the procedure.
How does MRI work?
Magnetic resonance imaging is an examination technique that utilizes magnetism. The MRI machine is essentially a large, circular magnet - and a strong one at that. Our magnet operates at 1.0 tesla, which is about 20,000 times stronger than the earth's magnetic field. The patient is placed into the center of this magnet. Radio frequency pulses are emitted. These pulses stimulate the many hydrogen atoms in our body, causing them to give off a signal. To form the basis for the MRI image, a computer then reads the signals.
How is MRI different from an x-ray?
While x-rays only enable us to see four densities (air, fat, muscle and bone), MRI displays these things and much more. It not only shows soft tissues, but also allows us to differentiate between fat, muscle, tendons and ligaments - showing them each as separate structures. In this way, we are able to examine the physiology of tissue. We can analyze blood flow into and out of organs, and can analyze heart muscle, blood vessels and other structures.
What types of problems is MRI used to diagnose?
MRI is commonly used to diagnose problems of the head and soft tissues of the neck. We can check for spine problems such as slipped or herniated discs, and can examine a variety of orthopedic problems - like knees, shoulders, etc. MRI may also be used to determine the extent and growth of some tumors.
What does the patient experience?
Because MRI doesn't use radiation, the procedure is very safe. The patient lies still for the scan, which takes 30 minutes. Generally, patients hear a tapping sound caused by changes in the magnetic gradients. A very small percentage of the population may experience some claustrophobia, be we have a variety of ways to help those patients be more comfortable.
For more information about MAGNETIC RESONANCE IMAGING, see our article about the DRMC MRI suite, or call the Health Referral Service at (434) 799-WELL or toll-free at 1-877-799-WELL.
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