Why nuclear magnetic imaging is called so?

Question

Why nuclear magnetic imaging is called so?

Answer 1

Hi Salman A.,

The name comes from the fact that, using a combination of a magnetic field and a radiofrequency excitation, you are causing the nuclei of certain elements (in general, hydrogen; in this case you are imaging the water content of various tissues) to flip their spin from up to down, or vice versa, with respect to the direction of the magnetic field. When a nucleus does this flip, it absorbs a "photon" of the radiofrequency radiation. That loss of radio field intensity can be detected. The imaging part comes from the technology to generate subtle magnetic field gradients in the x-y-z coordinates of the object to be imaged (such as, you!), such that only very small volumes of space are "interrogated" for their water content at a particular time -- all other portions of you are not at the proper combination of magnetic field and radiofrequency to be at the exact "flip" possibility (in resonance with the flip frequency). The reason that the magnetic field is varied, is that it can be! Whereas, the radiofrequency frequency would be constant across your entire body.

-- Cheers, -- Mr. d.