What is an MRI?

The MRI machine is a large, tube-shaped machine that uses a large magnet, radiofrequencies, and computers to form two-dimensional (2D) images of the body area being studied. Cross-sectional views can be done to show more details. MRI does not use radiation, like X-rays or computed tomography (CT scans), and may be used instead of a CT scan when organs or soft tissue are being studied. An MRI may be done with or without “contrast.” Contrast refers to a substance taken by mouth or injected into an intravenous (IV) line that causes the particular organ or tissue under study to show up more clearly on the scan.