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. An MRI differs from a CAT scan (also called a CT scan or a computed axial tomography scan) because it doesn’t use radiation.
An MRI scanner consists of 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 centers have open MRI scanners that have larger openings and are helpful for patients with claustrophobia. MRI scanners are located in hospitals and radiology centers.
During the examination, radio waves manipulate the magnetic position of the atoms of the body, which are picked up by a powerful antenna and sent to a computer. The computer performs millions of calculations, resulting in 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. These images help to pinpoint problems in the body.