MRI (definition of)

"MRI" is the acronym for Magnetic Resonance Imaging. This is a noninvasive, painless form of medical imaging that pathologists use in diagnosing disease. The MRI uses a powerful magnetic field, radio waves and a computer in order to produce detailed, three-dimensional computer models of the internal areas of the body. Unlike X-rays, the MRI is not radioactive nor produces radiation.

Through the use of magnetic fields and radio waves, an MRI scanner analyzes differing degrees of water content among various tissues. Disease often affects the water content of tissue, so radiologists are able to see abnormalities such as tumors when these are present. This allows physicians to better evaluate the disease in terms of accurate diagnosis and staging - which in turn is invaluable when it comes to planning a course of treatment.

In some cases, the patient may need to swallow a special dye or receive it intravenously. The patient then lies on a table that retracts into a large cylinder, around which a large, circular magnet is rotated. (Because of this, patients must not dress in clothing t hat contains metal, and the procedure may not be possible for people who have metal in their bodies, such as a metal plate or a pacemaker.) MRI equipment is rather loud during operation, so earplugs are provided for the patients. The test takes less than an hour, and the device operates intermittently for several minutes at a time during the imaging.

MRI scans are sometimes needed to determine the extent of a cancer such as mesothelioma and provide information regarding the most effective course of treatment.