Magnetic Resonance Imaging

From Chempedia

Peter Clark
Sam Buntrock
Benjia Hu

Scientist in 1952 won a Noble Prize for discovering Magnetic Resonance Imaging with the relationship magnets have with aligning atoms. MRI, short for, Magnetic Resonance Imaging, allows doctors to see detailed images of muscles, ligaments, tissues and other soft tissues in the body that x-rays cannot pick up. Doctors use MRI’s as a main tool to help out with the diagnosis of certain problems or diseases in the body. By using MRI the use for some surgeries can be eliminated. Currently there are no side effects from the MRI procedures, completely painless and can be preformed on almst everyone. The MRI machine gathers information from the use of the astronomical amount of hydrogen atoms that are found in the body. The magnet creates a field right through the center of the tube. This magnetic field makes these hydrogen atoms line up toward the feet or toward the head (pictured number 1 below). The atoms are aligned and now the machine emits a radio frequency that makes the non-aligned hydrogen atoms to spin (Erlangen). The radio signal that is sent into the body is turned off and on and allows the spinning hydrogen atoms to realign. This realignment happens in different intervals of time depending on the tissues or body parts the radio signal is being sent through. An example of this is the relaxation of hydrogen in blood and cerebrospinal fluid is a lot longer then that in fat tissues which is 300 milliseconds (Hornak). The different time intervals that the realignment and relaxation occur shows up as different contrasts of brightness to produce images or the area under examination. The energy that comes from the spinning atoms are then applied to a coil which is very close to the area of the body being examined. Then, there are three more magnets called gradient magnets that pulse on and off very rapidly and make a disturbance in the magnets main field. There is a loud hammering type sound that goes on during the use of the MRI machine. This sound is created when the magnets are turned on and off to get the atoms to align. When the atoms slow down from the switching of the radio frequencies changing, they give off an energy, which the coils receive. The signals finally are converted by using a computer and are transformed into mathematical data which the computer analyzes it an then can finally be made into a film. The images that can be produced by using MRI are very helpful in diagnosing multiple sclerosis, tumors, infections, tendonitis and even stokes in their very early stages. It also does a great job visualizing torn ligaments, shoulder injuries and evaluating bone tumors and much more (Ballinger). Some disadvantages with MRIs are that some people cannot be safely scanned because they have pacemakers or they are too big to fit into the machine. Other people may be too claustrophobic and will become very uncomfortable during the process. Humans that have plates, screws or artificial joints may cause the images that have been produced to become distorted (Hornak). Overall MRI has come so far and has been a very useful piece of equipment to diagnose diseases and other health complications.

Works Cited

Hornak, Joseph P. The basics of MRI. 29 Sept 2005. 1996-2004. <[1]>

Ballinger, Ray. Introduction to MRI. 29 Sept 2005. 15 November 2005 <[2]>

Erlangen. Magnets, Spins, and Resonances. Siemens. 2003. pg 4-25.

Gompel, S. van, Stoute, M. Tilborgh, A. van. mri.ontheweb.nl. 29 Sept 2005. 1999-2002. <[3]>

All pictures are from www.google.com