After Traumatic Injury, Diffusion Tensor Imaging Reveals How Some Brains Compensate

Using a specialized magnetic resonance imaging (MRI) technique to image patients with mild traumatic brain injury (MTBI), researchers have identified a biomarker that may forecast which patients will do well over the long term.

The study’s findings were presented at the annual meeting of the Radiological Society of North America (RSNA), held November 25-30, 2012, in Chicago, IL, USA. The study revealed that in some patients’ brains may have adapted to compensate for the injury caused by the injury. “This finding has huge potential implications for preventing and repairing the damage that accompanies traumatic brain injury,” said Michael Lipton, MD, PhD, associate director of the Gruss Magnetic Resonance Research Center at the Albert Einstein College of Medicine (Bronx, NY, USA) and medical director of MRI at the Montefiore Medical Center (Bronx, NY, USA).

MTBI, or concussion, accounts for at least 75% of all traumatic brain injuries. Following a concussion, some patients experience a short-term loss of consciousness. Other symptoms include dizziness, headache, memory loss, depression, attention deficit, and anxiety. Some of these symptoms may last for months or quite possibly years in as many as 30% of patients.

Dr. Lipton and colleagues set out to determine the postconcussion symptoms and health-related quality of life for a group of patients with MTBI one year post-injury. The researchers recruited 17 patients with MTBI from the emergency department of Montefiore Medical Center. Within two weeks of their injury, the patients underwent diffusion tensor imaging (DTI), which measures the direction of movement of water molecules within and along axons, which comprise the bundles of nerve fibers in the brain’s white matter. “In a traumatic brain injury, it’s not one specific area that is affected but multiple areas of the brain connected with axons,” Dr. Lipton said.

The researchers, using DTI, measured the uniformity of water flow, which is called fractional anisotropy [FA], throughout the brain, targeting areas with low FA, which are key characteristics of axonal injury, and areas with abnormally high FA, as compared to healthy brains. “Abnormally low FA within white matter has been associated with cognitive impairment in patients with TBI,” Dr. Lipton said. “We believe that high FA is evidence not of axonal injury, but of brain changes that are occurring in response to the trauma.”

The patients completed two standard questionnaires to evaluate their postconcussion symptoms and assess their quality of life and health status one year after their brain injury. Comparing the DTI data to the patient questionnaires, the researchers discovered that the presence of abnormally high FA was a predictor of fewer post-concussion symptoms and higher functioning.

These findings suggest that in patients who exhibit areas of high FA on DTI, the brain may be actively compensating for its injuries. “These results offer us a new opportunity for treatment by finding ways to enhance the brain’s compensatory mechanisms.” Dr. Lipton concluded.

Related Links:
Gruss Magnetic Resonance Research Center at the Albert Einstein College of Medicine