How Magnetic Resonance Imaging (MRI) Works

"Magnetic Resonance Imaging is used in for medical imaging. The procedure for an MRI is the following. Unlike an X ray examination or CT scan MRI does not depend on ionizing radiation. Instead while in the magnet, radio waves redirect the axes of spinning protons. The magnetic field is produced when electric currents are passed through wire coils. Other coils as side from these coils, located in the machine which are plased around the body being imaged recieves and sends radio waves. They then produce signals. A computer picks up these signals and generates a series of images. Thus the image can be studied. This is the basic sturture of how an MRI works. During the examination people must be still and some times asked to hold their breath by the docter. This is all procedures to can an accurate MRI."

How Magnetic Resonance Imaging Works
(Nuclear magnetic resonance imaging provides safe nonintrusive medical diagnostic images of the interior of the human body. How does MRI work?)
One of the many modern diagnostic tools available to medical doctors is magnetic resonance imaging (MRI). MRI scans provide physicians a view of the interior of the patient's body without harming or invading the patient's body in any way. Magnetic resonance imaging is based on the fundamental physics of nuclear magnetic resonance (NMR). How does MRI work?
Nuclear Magnetic Resonance
Nuclear magnetic resonance is an effect that occurs when the nucleus of an atom is placed in a magnetic field. The spinning nucleus in a constant magnetic field wobbles just like a spinning top.
If in addition to the constant magnetic field, there is another magnetic field that varies at the same frequency as the nucleus wobbles, the nucleus will flip back and forth so that the nucleus effectively alternates the direction in which it spins. As the nucleus flips its spin direction, it either absorbs or emits low energy radio waves. Studying these radio waves allows physicists to deduce various properties of the atomic nuclei undergoing NMR.
Safety of NMR and MRI
Nuclear magnetic resonance uses the word nuclear because it involves the nucleus of the atom. It does not however in any way involve any dangerous radiation as people expect from nuclear weapons or other nuclear reactions. The only radiation patients are exposed to by nuclear magnetic resonance imaging is very low energy radio waves. Nuclear magnetic resonance imaging is therefore very safe. The word nuclear was dropped however to allay patient fears. To the average person magnetic resonance imaging sounds less dangerous than nuclear magnetic resonance, and MRI is very safe.
Magnetic Resonance Imaging
Magnetic resonance imaging is a very useful application of NMR. Medical MRI machines are designed to image the nuclei of the hydrogen atoms in the human body. Human bodies contain a high percentage of water, so there are a large number of hydrogen atoms in all human tissue. X-rays image bones well, but image other tissues very poorly. Magnetic resonance imaging therefore provides medical personnel with much better images of the soft tissue in the patient's body than X-rays can provide.

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