Guest Author - Lisa Shea

MRI, or Magnetic Resonance Imaging, involves a gigantic magnet which allows doctors to see within the human body.

The very first MRI was done on July 3, 1977. Less than 25 years later, there were thousands of MRI machines in operation, performing full scans in only a few minutes.

In essence, the MRI works on the body in layers. It sends a very precise radio wave at a certain section of the body. The way in which the radio and magnet interact with the tissue at that intersection point tell the machine what exact type of item was there - bone, muscle, fat, or so on. By moving "slice by slice" through a given section of the body, the machine can then build a 3D computer map of the area that can be viewed from any angle.

Because the MRI system works with extremely powerful magnets, it is critical that nothing metal be anywhere near the machine. For example, if the person had earrings on, they would easily be ripped out of the person's ear and sucked to the magnet. Larger metal items could cause far more damage as they "flew" to contact the magnet.

Even though there are thousands of MRI machines in the world today, they are still in extremely high demand 24 hours a day. Even movie producers, with their millions of dollars of budgets, cannot get time with an actual MRI machine in order to film scenes. They do scenes with fake MRI machines, and even those are so few that it costs a lot of money to do that!