Reported March 2009

WHAT IS A DIFFUSE AXONAL INJURY? Axons are fibers that act as the transmission lines that flow through the body. Bundles of axons are called nerves. In the brain, axons extend from one part of the brain to another. They can be damaged in car accidents or other collisions. For example, a concussion is a mild diffuse axonal injury. When damaged, axons absorb water. Later they may die and release the water. The injury is very difficult to diagnose, but by comparing MRI images over time, doctors can detect changes in water motion around nerve cells, which indicates diffuse axonal injuries. Symptoms include dizziness, headaches, memory issues, anxiety and mood disorders.

HOW MRI WORKS: Magnetic resonance imaging uses radio frequency waves and a strong magnetic field instead of X-rays to provide clear and detailed pictures of internal organs and tissues. These radio waves are directed at protons in hydrogen atoms -- one of the most abundant atoms in the human body, because of the body's high water content. The waves "excite" the protons, and when they "relax," they emit strong radio signals. A computer can turn those signals into a high-contrast image showing differences in the water content and distribution in various bodily tissues.

The American Association of Physicists in Medicine contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Aline McKenzie
Senior Communications Specialist
UT Southwestern Medical Center at Dallas
(214) 648-3404
aline.mckenzie@utsouthwestern.edu

Dr. Sudarshan Chamakuri
Medical Physicist
American Association of Physicists in Medicine
radiationtherapy@hotmail.com

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