Magnetic Resonance Imaging (MRI) is similar to an x-ray in regard that it allows doctors, medical practitioners and students to examine the internal structures of the body without tearing apart the outer skin. There are three key differences between an x-ray and Magnetic Resonance Imaging.
The first and foremost is that x-rays utilize high-energy particles/waves which in large doses are known to cause damage to tissue. MRI uses lower energy waves which are not known to cause any damage, but the important thing to remember is that research is still going on this regard and henceforth the results are positive about the fact that MRI doesn’t have any side affects.
The second important difference is that most x-ray imaging is two-dimensional where as MRI is three-dimensional. X-ray imaging uses the pinpoint camera method to create an image. Basically the machine emits a stream of high energy photons at a target with a film behind it. Certain substances in the target (bones, metal) will absorb or deflect more of the photons than other substances (soft tissue, H20). The film on the other side of the target will change chemically in the areas where more photons got through so that a developing process, akin to that of normal film, will show the shapes of things inside the target which blocked or deflected particles. This process produces a two-dimensional image.
On contrary, an MRI is akin to cross between a microwave and the mechanism used to determine the locations of earthquakes. The Magnetic Resonance Imaging machine emits magnetic waves tuned to the properties of certain atoms and then listens for the echoes of the atoms it’s scanning. Since this is happening electro-magnetically, it’s not really listening, but more like watching. However, since the waves are only resonating and not bouncing off of things, they are able to permeate the entire target under scrutiny. The MRI machine can tune its emitters and detectors to any particular slice of the subject and resolve a two-dimensional image of that slice revealing how each portion of the slice resonated with the fields the machine created.
The third salient difference is that the fields used in an MRI can be tuned to different substances to change the tissues or chemicals which will resonate in an image. The machine can smell different kinds of atoms and molecules by combining information from different field type scans. Also, when used in medicine, doctors will sometimes supply a patient with certain substances to enhance the use of MRI.
The blend of low-energy physics, three-dimensional resolution and the ability to detect a wide range of substances has made MRI an incredibly powerful tool for examining the insides of things without taking them apart.
P.S. This little research was carried out by using wikipedia. If anyone, especially the doctors and medical experts could add something, then it would be highly appreciated.