Nuclear magnetic resonance imaging (NMRI) — also known as magnetic resonance imaging (MRI) — is a medical technique used to take images of different parts of the human body to help with diagnosis. A nuclear magnetic resonance image provides a much greater level of contrast compared with other imaging techniques such as CT scans. Some of the areas of the human body that can be imaged especially effectively with an NMRI scan include the brain and musculoskeletal system. Compared to other imaging techniques, NMRI is a relatively new technology and has been used since the late 1970s.
Nuclear magnetic resonance imaging machines make use of the fact that the body is mainly made from water. Water contains two protons that are affected by a magnetic field. The NMRI machine produces a strong magnetic field, which makes the protons align in a certain direction. Once the protons are aligned, a radio wave is transmitted at just the right energy to “flip” the protons, which then “flip” back once the radio wave disappears. When the protons flip back they can be detected by the machine, creating a map of the area of body.
One of the most effective applications of an NMRI machine is to identify cancerous from regular tissue. This is often how brain tumors are detected. Another example is to detect problems in a joint such as the knee. An MRI provides much more information than an X-ray in this case as it can image the tissue of the joint rather than just the bone structure.
A major benefit of an MRI machine compared to other forms of imaging is that it is harmless. Instead of using high-energy radiation such as in X-ray machines an MRI uses magnetic fields, which aren’t thought to cause any negative side effects. MRI images also provide much greater contrast between different types of tissue, which aids in diagnosis.
Nuclear magnetic resonance imaging systems rely on the development in physics of nuclear magnetic resonance. For this reason the first machines were called nuclear magnetic resonance imaging machines. This name, however, was later changed to magnetic resonance imaging as it was thought that the term nuclear had negative connotations in the public eye. For this reason, most in the medical profession now use an MRI rather than NMRI. Scientists, however, use NMRI for machines which use the same techniques but aren’t used for medical purposes.