Washington: With the help of special type of magnetic resonance imaging (MRI), researchers have found that soldiers who suffered mild traumatic brain injury (MTBI) induced by blast exposure exhibit long-term brain differences.
Study co-author P. Tyler Roskos , Ph.D., a neuropsychologist and assistant research professor at the Saint Louis University School of Medicine in St. Louis, said while mild traumatic brain injury is difficult to identify using standard CT or MRI, some methods may have added sensitivity.
One of those methods is diffusion tensor imaging (DTI), an MRI technique used to identify microstructural injury to white matter, the part of the brain that consists mostly of signal-carrying axons.
Damage-associated changes in water movement along the axons are comparable in certain respects to what might happen with a garden hose, according to co-author Thomas M. Malone, B.A., research associate at Saint Louis University School of Medicine.
In the study, researchers compared DTI-derived fractional anisotropy (FA) values in 10 veterans of Operations Iraqi Freedom and Enduring Freedom who had been diagnosed with MTBI with those of 10 healthy controls.
FA measures the uniformity of water diffusion throughout the brain, and low FA tends to indicate areas of axonal injury. The average time elapsed between the blast-induced injury and DTI among the patients was 51.3 months.
Comparison of FA values showed significant differences between the two groups, and there were significant correlations between FA values and attention, delayed memory and psychomotor test scores. Since the victims were, on average, more than four years removed from their injuries , the results suggest the presence of a long-term impact of blast injury on the brain .
The results also indicate that DTI is sensitive to group differences in blast-related MTBI even in the post-acute phase.
The study was presented at the annual meeting of the Radiological Society of North America (RSNA).
