Magnetic resonance imaging (MRI) is a procedure used to diagnose and evaluate injuries and diseases. MRI scans use large, powerful magnets and a specialized computer to produce high-resolution cross-sectional images of the soft tissues and bones.
A typical MRI scan takes from 20 to 90 minutes, depending on the part of the body being imaged. MRI scans are used to image the non-bony parts or soft tissues of the body such as the:
- Bones and joints
- Heart and blood vessels
- Internal organs
- Spinal cord and nerves
Prior to an MRI exam, patients are asked remove metals and other objects that might affect the magnetic imaging, such as:
- Cosmetics that contain metal particles
- Hair accessories
- Hearing aids
- Underwire bras
MRIs are not painful but they can be very noisy, with a lot of tapping or thumping noises, so earplugs or headphones may be given to a patient to help muffle the sounds.
During an MRI exam, a patient usually lies on a table that slides into a tube-shaped MRI scanner, which is the bore of the magnet, for imaging. During the exam, the patient is able to communicate with a technologist who is in another room.
An electric current passes through coiled wires to create a magnetic field in the area of the patient’s body that needs to be imaged. Radio waves cause the body tissues to vibrate and create digital images of the scanned area of the body. A computer records the rate at which the body part emits the vibrations, and translates the data into a two-dimensional image.
Sometimes, intravenous (IV) gadolinium-based contrast agents (GBCAs) are used to enhance the contrast and detail of the images.