Magnetic Resonance Imaging
Magnetic Resonance Tomography (MRT)
It is a method of creating images of the inside of opaque organs in living organisms as well as detecting the amount of bound water in geological structures. It is primarily used to demonstrate pathological or other physiological alterations of living tissues and is a commonly used form of medical imaging. MRI has also found many niche applications outside of the medical and biological fields such as rock permeability to hydrocarbons and certain non-destructive testing methods such as produce and timber quality characterization. Medical MRI most frequently relies on the relaxation properties of excited hydrogen nuclei in water.
In clinical practice, MRI is used to distinguish pathologic tissue (such as a brain tumor) from normal tissue. One of the advantages of an MRI scan is that, according to current medical knowledge, it is harmless to the patient. It utilizes strong magnetic fields and non-ionizing radiation in the radio frequency range. Compare this to CT scans and traditional X-rays which involve doses of ionizing radiation and may increase the chance of malignancy, especially in children receiving multiple examinations.
While CT provides good spatial resolution (the ability to distinguish two structures an arbitrarily small distance from each other as separate), MRI provides comparable resolution with far better contrast resolution (the ability to distinguish the differences between two arbitrarily similar but not identical tissues).
The presence of a ferromagnetic foreign body (such as shell fragments) in the subject, or a metallic implant (like surgical prostheses, or pacemakers) can present a (relative or absolute) contraindication towards MRI scanning: interaction of the magnetic and radiofrequency fields with such an object can lead to: trauma due to shifting of the object in the magnetic field, thermal injury from radiofrequency induction of heating of the object, or failure of an implanted device.