Two separate projects, spearheaded by University of Pittsburgh Schools of the Health Sciences researchers, represented important steps toward demonstrating on patients the utility of portable, optical brain imaging for concussion and substantiating—via a large-scale statistical analysis—computerized neurocognitive testing for concussion.
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The findings from the optical imaging research, employing functional near-infrared spectroscopy (fNIRS), provided preliminary support for the tool as a low-cost, portable device for imaging sports and military concussions, researchers said. That report, published in Brain Imaging and Behavior, quickly led to further research—a National Institutes of Health (NIH)-funded study examining the brain during dual cognitive-balance performance in children following concussion.
The fNIRS unit works like a pulse oximeter for the brain. It measures blood flow to the brain by sending light signals from sensors mounted in a 3 lb headcap, then producing images of blood oxygen changes—representing brain activity—by recording the absorption of light at different colors. The fNIRS produced readouts while participants wearing the bandana-like headcap took a computerized neurocognitive test and matched the test in revealing the brain’s struggles to complete specific cognitive tasks.
“We hypothesize that cerebral blood flow is affected post-injury, and brain processing is going to be less efficient,” explained Anthony Kontos, Ph.D., assistant research director, UPMC Sports Medicine Concussion Program and assistant professor, Pitt Department of Orthopedic Surgery. “If you’re performing a memory task or reaction-time task, it would require activation—more blood flow, more oxygen needed—in certain areas of the brain specific to that task. However, we found decreased and more spread out activation in the concussed group. In other words, their injured brains were less efficient and strained to get from elsewhere in the brain the resources necessary to perform cognitive tasks.”
“We knew what brain areas normally should light up,” added Theodore Huppert, Ph.D., assistant professor, Magnetic Resonance Research Center, Pitt Department of Radiology and Swanson School of Engineering. “From our data set, we had on average decreased brain activity and more diffuse brain activity—where more areas of the brain were needed to accomplish the task because the usual areas weren’t as efficient.”
This preliminary study included nine people between ages 18 and 45 who were symptomatic within 15 days to 1.5 months of a sports-related concussion. Researchers compared them to five people who were uninjured. The fNIRS scans indicated that the concussed brain activated at a lower threshold and drew from a wider area — a sharp contrast from earlier functional magnetic resonance imaging (fMRI) studies using concussion patients. And the decrease in oxygenated blood flow and lower test performance were detected during certain, more cognitively strenuous aspects of neurocognitive testing: word memory, design memory and symbol matching.
“It’s a portable and fairly inexpensive imaging device—compared to MRI—and most important, it allows us to combine both spatial and temporal information, meaning what is going on in a specific area of the brain and when the activation is occurring,” Dr. Kontos said. “It’s not just location. It’s not just timing. It’s both.”
A wireless fNIRS device is expected on the market soon, availing it for further research in a clinical and perhaps even a sideline concussion setting said Dr. Huppert, who has worked with and published research on fNIRS for years. Yet Dr. Kontos underscored the utility of the current iteration: “You can wear this while doing neurocognitive testing, you can wear this during balance-testing, you can even wear it while doing exertional testing, like on a treadmill. It’s useable in an environment for sports-related concussion.”
The fNIRS study used ImPACT, a computerized neurocognitive test battery designed to assess mild traumatic brain injury. Dr. Collins is a developer and shareholder of ImPACT Applications, Inc., the maker of ImPACT.
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