MRI-based technique finds post-traumatic brain injury

Diffusion kurtosis imaging (DKI), a new MRI-based technique, may help find hard-to-detect lesions in patients with mild traumatic brain injury, according to a study presented at the 2006 International Society for Magnetic Resonance in Medicine meeting. DKI could help understanding of persistent post-traumatic disorders affecting these patients.

Conventional diffusion tensor imaging gauges tissue's water diffusion, assuming a specific displacement distribution pattern. But water movement often contradicts this pattern, a sign of potentially anomalous tissue structure and pathophysiology. DKI, which includes conventional DTI data. can provide an accurate means of measuring this phenomenon, said lead investigator Dr. Robert Grossman, director of radiology at New York University.

Grossman and colleagues assessed 16 patients with mild traumatic brain injury and 14 age-matched healthy control subjects using DKI on a 3T scanner. The method provided significant indications of damage in the thalamus of patients with mild traumatic brain injury.

Conventional MR imaging provided no remarkable findings in the thalamus of patients with known brain trauma. Researchers found no significant differences in fractional anisotropy or mean diffusion rates in the thalamus of patients and normal controls. DKI, however, showed lower mean kurtosis rates in the thalamus of patients with mild traumatic brain injury when compared with age-matched normal controls. The difference was statistically significant (p<0.0001).

The investigators also measured other basal ganglia regions, including putamen and caudate nucleus as well as frontal white matter, and found no statistically significant differences between patients and controls. Findings suggest the thalamus, a sizable region located in the center of the brain, may be more prone to traumatic injury, Grossman said.

U.S. specialists worry brain trauma may be turning into a silent epidemic, since more than one million people suffer some form of mild brain injury each year. Patients show post-traumatic symptoms such as headaches, memory loss, and tingly or numb limbs that last for a few months to several years. The costs associated with management of these symptoms could reach several billion dollars.

Standard CT or MR techniques can detect the thalamic damage responsible for diverse neuropsychological function impairment in patients with severe traumatic brain injury. But they may not be able to detect subtle thalamic lesions in patients with mild traumatic brain injury. DKI can find precisely these lesions during a 10-minute scan, the researchers said.

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