NMR technique gave birth to Magnetic Resonance Imaging which proved to be a boon for the medical diagnosis professionals. Magnetic Resonance Imaging (MRI) revolutionized medical investigations by providing non-destructive and non-invasive means of tissue investigation prior to prescription. The technique is harmless as unlike X-rays and CT techniques which make use of ionizing radiations or radioactive material MRI uses non-ionizing radio waves.
The technique may not be of much interest to the laboratory chemist but as it is in important offshoot of the popular analytical NMR technique it deserves a brief mention.
What is Magnetic Resonance Imaging?
Magnetic resonance imaging is a proven safe technique used in hospitals across the world. It provides both harmless and painless investigation through sliced images of internal organs and tissues of the body. It uses a large magnet, radio wave coils and a computer to generate cross- sectional images of internal organs.
A human body is composed predominantly of water molecules which are randomly arranged. However, under the influence of the MRI magnet the molecules align themselves unidirectionally. A second magnetic field is turned on and off in a pulsed manner which relaxes the molecules to the original orientations. The field is turned off to register the body’s electromagnetic transmissions and the recorded signals provide the internal mapping of body organs.
1937 – Prof Rabi of Columbia State University, New York discovered presence of absorbing and emitting radio waves when atomic nuclei are exposed to a strong magnetic field
1971 – Prof Raymond Damadian discovered that the hydrogen signal in cancerous tissue is different from that of normal tissue as cancerous tissues contain more water. The decay signal on switching off the magnetic field from cancerous tissue takes longer than the signal from the normal tissue.
1973 – Paul Lauterbur produced the first MRI image
1977 – Damadian generated first full body scan of a human being taking nearly 5 hours
2003 – Lauterbur shared the Nobel prize in physiology and medicine for his contributions to MRI
Diagnostic Applications of MRI
MRI images provide a non-invasive and harmless diagnosis tool in the hands of medical experts. Some typical applications are:
- Detection of tumors and cysts
- Heart malfunctions
- Compressed nerves in spinal column
- Abnormal tissue growth in brain
- Pelvic disorders in women
Most conditions are not apparent to the patient but MRI diagnosis helps in early-stage detection and prescription of remedial action to prevent future complications.