Magnetic resonance imaging (MRI) is a safe and painless test
that uses a magnetic field and radio waves to produce detailed
pictures of the body's organs and structures. Unlike CAT scans
or X-rays, MRI doesn't use radiation. An MRI scanner is a large
doughnut-shaped magnet that often has a tunnel in the center.
Patients are placed on a table that slides into the tunnel. Some
hospitals and radiology centers use what are called "open" MRI
machines. They have larger openings and are helpful for patients
with claustrophobia (a fear of being in tight, enclosed spaces).
During the MRI exam, radio waves manipulate the magnetic
position of the body's atoms, which are picked up by a powerful
antenna and sent to a computer. The computer does millions of
calculations to create clear, cross-sectional black-and-white
images of the body. These images can be converted into three-
dimensional (3-D) pictures of the scanned area that can help
pinpoint problems in the body. MRI is used to: provide clear
images of body parts that