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What is MRI and how does it work?

Magnetic Resonance Imaging, also known as MRI, is a way of obtaining very detailed images of organs and tissues throughout the body without the need for x-rays or "ionizing" radiation. Instead, MRI uses a powerful magnetic field, radio frequency waves, rapidly changing magnetic fields, and a high-tech computer to create images that show whether or not there is an injury, disease process, or abnormal condition present. For this procedure, the patient is placed within the MR scanner—typically a large, tunnel or doughnut-shaped device that is open at both ends. The powerful magnetic field aligns atomic particles called protons that are present in all of the body's tissues. The applied radio frequency waves give energy to these particles. As the energy is released, a current is induced in the receiver, located within the magnet. These signals are then processed into recognizable images by a very advanced computer.  The signals are specially characterized using the rapidly changing magnetic field, and very sharp images of tissues are created as "slices" that can be acquired in any orientation.


An MRI exam causes no pain, and the magnetic fields produce no known tissue damage of any kind. The MR scanner may make loud tapping or knocking noises at times during the procedure; using earplugs prevents problems that may occur with this noise. You will be able to communicate with the MRI technologist or radiologist at any time using an intercom system or by other means.

read more from:

http://www.radiologyinfo.org/en/safety/index.cfm?pg=sfty_mr