The Role of Imaging in Pediatric Traumatic Brain Injury
New imaging technology is helping show what's normal versus not normal development in a pediatric brain
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The role of imaging in--especially in pediatric imaging has been really under-utilized up until the present time, and this is largely because the developing brain makes it a challenge for most standard imaging techniques because of this increase in myelination that occurs with development. The increase in myelination actually makes it very difficult to differentiate between different tissue types in the brain, and so standard imaging with CT or MRI has done a really poor job at characterizing discrete or even subtle injuries in the brain. And so within the past 10 years or so, with the advent of a new technology, newer technology called diffusion tensor imaging, we've come a long way into characterizing not only what's normal development but also then what's abnormal development. So the advantage of diffusion tensor imaging, or DTI, is that it allows us to look at how water diffuses in the brain. So, we're made up of 98% water. Our brain is no different than that and, generally speaking, water is restricted by the same tissues or same structures that you would have in the plumbing in your house. So water is free to run through a pipe, but you're not going to see it leaking out of a pipe unless there is damage to that pipe itself. Our brain works the same way, but instead of pipes there are these white-matter fiber tracks which are coated in myelin, which is an insulation, and also with axonal membranes. And these two structures keep the water diffusing within the track itself rather than going across it. With brain injury, and with normal development, you see an increase in myelin, which means the restriction of water increases as development increases up to a point where it plateaus, somewhere around age 19 or 20, at which point we have a nice developmental curve for looking at myelination, and there has been some wonderful studies run by the National Institutes of Health that have started to create normative databases for what is normal age-related development in myelin. But it's this latest technology that's really pushed us to see imaging being useful not just in adults or injury, but just even in characterizing normal development.
Posted on BrainLine May 25, 2010.
Deborah Little, PhD is an associate professor of Neurology & Rehabilitation, Anatomy & Cell Biology, Ophthalmology & Visual Sciences, and Psychology at the University of Illinois.
Produced by Victoria Tilney McDonough and Brian King, BrainLine.