I have previously discussed the role of standard CT scans and MRI scans of the brain. Both methods are highly insensitive in detecting brain injury from concussion and traumatic brain injury (TBI). They will only detect bleeding in the brain, and this is only present in a small percentage of cases of brain injury.
A brief discussion of the brain is in order.
The brain is made up of white matter and grey matter. At autopsy, you can actually see the difference in color. Grey matter holds the bodies of neurons and where the connections between neurons take place (the synapse). White matter are the axons (or wires of the brain), where the information is actually transported from one part of the brain to another part. These bundles are very important in brain function and can only be measured by
Diffuse tensor imaging, a specialized MRI scan which looks at movement of water molecules.
Now, this is not a brand-new technology, but has become increasingly important in evaluating TBI patients. It seems to correlate more closely with cognitive deficits detected by neuropsychologists, (specialists who administer tests to measure the cognitive impairment in TBI patients). The flow of water down axons (like wires) transmits information from one processing area of the brain to another. This is critical in normal cognitive function. When these rivers of information are disrupted, that can be measured by Diffuse Tensor Imaging (DTI). Thus, the DTI image looks more like a wiring diagram than an actual photographic image of the brain.
These DTI images more closely parallel actual cognitive deficits in head injury patients. The brain must talk to itself to work properly. DTI is not available routinely, but is being used more and more in TBI patients. There is abundant evidence in the academic literature to support its application. Like any brain scan, it is far from perfect, and leaves many questions unanswered (such as, what is going on at the cellular level: a topic for another day).
But we are entering a new era in TBI evaluation and research. We need more from neuroimaging than the standard ER CT scan or the follow up standard MRI scan. These tests are great for many neurological diseases, but not great for TBI. Many of the football players suffering from Chronic Traumatic Encephalopathy (CTE) have normal scans. Many new tests are being developed to assess head injury patients.
Diffuse Tensor Imaging looks like an important tool, and it exists right now.
Steven H. Rauchman, M.D. is an eye physician and surgeon who has been in private practice for 30 years. He has served as a Traumatic Brain Injury (TBI) medical/legal expert for the last 6 years specializing in the area of personal injury and related traumatic brain injuries.