The MRI machine looks like a long narrow tube that has both ends open. If you think of a CT machine as a donut, you can think of an MRI as more of a tissue paper roll. You lie down on a movable table that raises and slides into the opening of the tube. A technologist monitors you from another room. You will be given a squeeze ball should you need your technologist’s attention and you can also talked with them by microphone. If you have a fear of enclosed spaces (claustrophobia), you might be given a drug by your referring doctor to help you feel sleepy and less anxious. Most people get through the exam without difficulty. The MRI machine creates a strong magnetic field around you, and radio waves are directed at your body. The procedure is painless. You don't feel the magnetic field or radio waves, and there are no moving parts around you.
During the MRI scan, the internal part of the magnet produces repetitive tapping, thumping and other noises. You might be given earplugs or have headphones to help block the noise. In some cases, a contrast material, typically gadolinium, will be injected through an intravenous (IV) line into a vein in your hand or arm. The contrast material enhances certain details. Gadolinium rarely causes allergic reactions. An MRI can last anywhere from 15 minutes to more than an hour depending on the type of procedure or number of procedures being done in a single day. You must hold still because movement can blur the resulting images.