| MRI (Magnetic resonance imaging) is a non-invasive | | | | a single image in approximately 5 minutes using Ernst's |
| imaging technique that uses a combination of a large | | | | technique. In 1986, this time was reduced to |
| magnet, radio frequencies, and a computer to | | | | approximately 5 seconds. In 1993, functional MRI was |
| generate images of internal structures and organs of | | | | developed which showed the mapping of the function |
| the body without using x-ray radiation and surgery. | | | | of the various regions of the human brain. |
| MRI has been developed based on the principles of | | | | An MRI machine is a large tube-shaped machine |
| nuclear magnetic resonance. NMR (nuclear magnetic | | | | running through the magnet from front to end. The |
| resonance) was discovered by Felix Bloch and | | | | magnet creates a strong magnetic field around the |
| Edward Purcell in 1946. During the 1950s and 1960s, | | | | patient and sends pulses of radio waves from the |
| NMR (nuclear magnetic resonance) was used for | | | | scanner. These waves force the nuclei of hydrogen |
| chemical and physical molecular analysis. In 1971, | | | | atoms out of their normal position. As the nuclei |
| Raymond Damadian showed that the nuclear | | | | realigns into their normal position they send out radio |
| magnetic relaxation periods of tissues and tumors | | | | waves on their own. The computers or the scanners |
| differed. In 1973, Paul Lauterbur used a back projection | | | | identify these signals and analyze and convert them |
| technique similar to that used in CT scans and | | | | into pictures with minute details of the part of the body |
| demonstrated magnetic resonance imaging on small | | | | being examined. MRI scans are now widely used to |
| test tube samples. In 1977, Raymond Damadian came | | | | examine organs, detect tumors and in the diagnosis of |
| up with the first whole body MRI scanner and | | | | many forms of cancer and injuries in bones and |
| performed a whole body scan in 4 hours and 45 | | | | tissues. |
| minutes. In 1980, Edelstein and coworkers could acquire | | | | |