Magnetic Resonance Imaging

Figure 1. Early model MRI machine by General Electric (Source)

Brief: Magnetic resonance imaging was discovered at roughly the same time as an induced magnetic field. In 1882, Nikola Tesla discovered the rotating magnetic field. Professor Isidor I. Rabi observed the quantom phenomenon called the Nuclear Magnetic Resonance. This occurs when atomic nuclei show their presence when exposed to a sufficiently strong magnetic field. It was not until 1971 that Raymond Damadian found that cancerous tissue radiate radio waves longer than healthy cells when the NMR machine was turned off. He shortly applied for a patent afterwards in 1972. Being granted the patent in 1974, he produced the first MRI machine by hand and had the first successful test on a human patient. 1987, real time imaging is now capable over the heart and brain. By the late 1990's the MRI machine started to be used as a staple in medical centers throughout the world.

Figure 2. Modern Phillips MRI machine (Source)

Use: An MRI creates images of the human body using the NMR principle. Because it gathers data in slices across the body, any thin section can be isolate for further study. First, the human body is placed in a stable magnetic field. After the cells have stabilized, radio waves are exposed to the cells until they are saturated. The last step is the machine collects the radio signals and differentiates by the direction and wavelength to generate an image. Because of the strong magnetic field, it is important that everythin magnetic is removed before entering an MRI room. Of course this would have complications for those who have pacemakers or other implanted medical devices. 

Additional Information: General, Timeline, Timeline 2, General Info 2