Magnetic resonance imaging (MRI), formerly referred to as magnetic resonance tomography (MRT) and, in scientific circles, nuclear magnetic resonance imaging (NMRI) or NMR zeugmatography imaging, is a non-invasive method used to render images of the inside of an object. It is primarily used in medical imaging to demonstrate pathological or other physiological alterations of living tissues. MRI also has uses outside of the medical field, such as detecting rock permeability to hydrocarbons and as a non-destructive testing method to characterize the quality of products such as produce and timber.
MRI should not be confused with the NMR spectroscopy technique used in chemistry, although both are based on the same principles of nuclear magnetic resonance.
The scanners used in medicine have a typical magnetic field strength of 0.3 to 3 teslas. Construction costs approximately US$ 1 million per tesla, and maintenance an additional several hundred thousand dollars per year.