Definition
Heart magnetic resonance imaging (MRI) is a imaging method that uses powerful magnets and radio waves to create pictures of the heart. It does not use radiation (x-rays).The test may be done as part of a chest MRI.
Unlike x-rays and computed tomographic (CT) scans, which use radiation, MRI uses powerful magnets and radio waves. The MRI scanner contains the magnet. The magnetic field produced by an MRI is about 10 thousand times greater than the earth's.
The magnetic field forces hydrogen atoms in the body to line up in a certain way (similar to how the needle on a compass moves when you hold it near a magnet). When radio waves are sent toward the lined-up hydrogen atoms, they bounce back, and a computer records the signal. Different types of tissues send back different signals.
Alternative Names
Magnetic resonance imaging - cardiac; Magnetic resonance imaging - heart; Nuclear magnetic resonance - cardiac; NMR - cardiac; MRI of the heartHow the test is performed
You may be asked to wear a hospital gown or clothing without metal fasteners (such as sweatpants and a t-shirt). Certain types of metal can cause inaccurate images.You will lie on a narrow table, which slides into into a large tunnel-like tube.
Some exams require a special dye (contrast). The dye is usually given before the test through a vein (IV) in your hand or forearm. The dye helps the radiologist see certain areas more clearly.
During the MRI, the person who operates the machine will watch you from another room.
Several sets of images are usually needed. Single MRI images are called slices. The images can be stored on a computer or printed on film. One exam produces dozens or sometimes hundreds of images. Each image takes about 2-15 minutes. A complete scan may take up to 1 hour. Newer scanners may complete the process in less time.
