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MRI: Putting It All Together

Thursday, April 19, 2012 - 13:54

Contributing Author: Guy Slowik FRCS

Here is a summary of the important facts and information related to MRI.

  • Magnetic Resonance Imaging, or MRI, is a painless diagnostic procedure that uses a powerful magnet and radio waves to produce high-quality, cross-sectional images of organs and body structures without the use of X-rays or other ionizing radiation.
  • Because MRI does not involve the use of x-rays, it is safe for the majority of people. MRI uses low-energy, non-ionizing radio waves, so there are no known risks or side effects, even with repeated imaging.
  • The MRI scanning machine is a large donut-shaped magnet with a movable scanning table on which a person lies. The machine produces loud noises, like banging, during the procedure. The noises, while unpleasant at times, aren't dangerous or indicative of a problem, but are a signal that images are being taken.
  • The computer uses the MRI signals to create an image that is based on the strength of signal produced by different types of tissue. For example, tissues that contain little or no hydrogen (such as bone) appear black. Those that contain a large amount of hydrogen (such as the brain) produce a bright image.
  • In general, MRI is used to rule out certain diseases and to facilitate treatment for medical conditions.
  • For an "ordinary" MRI, no special preparation is required.
  • An entire MRI exam may take from 20 minutes to 1.5 hours, depending on the type of information required by the radiologist and physician, and the quality of the images needed to make a particular diagnosis.
  • Normal activities can be immediately resumed after the images are obtained.
  • Because the machine has a tunnel-like appearance, some people feel uncomfortable, or even claustrophobic (fearful of being closed in). Most people can overcome this feeling, but for those who need assistance, the doctor can prescribe a tranquilizer for use before the procedure.
  • Special scanners with open magnets exist for those people who are too claustrophobic and/or too large to fit in the regular machines. Unfortunately, the image quality of these scanners is generally not as good as it is from those with closed magnets.

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