Magnetic Resonance Imaging for Medical Diagnostics

Today's medical professionals use a variety of diagnostic tools to probe the condition of biological entities. One such technique is that of magnetic resonance imaging (MRI).

MRI works in the following manner. The patient is first placed in a strong magnetic field. The paramagnetic atoms become aligned with the direction of the field. The aligned hydrogen atoms take on resonance characteristics; that is, they can absorb energy and re-emit the energy as electromagnetic radiation at a specific frequency. A short pulse of radiofrequency (RF) waves is then sent to the body. The aligned protons (hydrogen) are excited and become deflected. Once the RF pulse is stopped, the protons realign with the magnetic field while emitting RF waves that are measured. The emitted RF waves contain information on both the physical and chemical characteristics and spatial distribution of body materials. For instance, an image representing the density of hydrogen nuclei within the body is produced. A tutorial on MRI can be found at http://www.mritutor.org/.

The electromagnet experiment serves to illustrate just a fraction of the physics behind MRI. The electromagnet interacts with metal objects on a macroscopic scale whereas the object of MRI is to take advantage of interactions on an atomic scale.

The electrical engineer is involved in the development of medical diagnostic procedures in a variety of ways, including:

  • Radiofrequency (RF) waves are studied in electromagnetics
  • Instrumentation is developed to measure the emissions
  • Signal processing techniques are used to analyze and enhance the images

[Source: Image Technology]

Teachers will find the Chickscope website at http://chickscope.beckman.uiuc.edu/ to provide a unique opportunity. The Beckman Institute Magnetic Resonance Imaging Laboratory has made their MRI available to schoolchildren (from kindergarten to high school aged) to learn about chicken embryology by operating the MRI microscope over the Internet. The MRI has an egg placed inside and can be accessed at certain times by each school via the web. Other educational material, including pictures, video and other links, are also included in Chickscope as well.

ASU Department of Electrical Engineering
Last Updated: June 21, 2002
Original Page Development by: Matt Dayley and Keith Holbert
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