Serial changes in diffusion tensor imaging metrics of corpus callosum in moderate traumatic brain injury patients and their correlation with neuropsychometric tests: a 2-year follow-up study.

OBJECTIVE: To assess longitudinally the severity of diffuse axonal injury in the corpus callosum in patients with moderate traumatic brain injury (TBI) through quantitative diffusion tensor imaging and to correlate these changes with neuropsychometric tests (NPT) at 6 and 24 months after injury.
DESIGN: Prospective longitudinal study. PARTICIPANTS: Sixteen patients with TBI and 17 age/sex-matched healthy controls.
METHODS: Patients underwent magnetic resonance imaging at 3 time points: within 2 weeks (range = 5-14 days), 6 months, and 24 months after injury. NPT could be performed only at 6 and 24 months.
RESULTS: In patients with TBI, a significant increase in fractional anisotropy (FA) values in genu as well as an insignificant decrease in radial diffusivity (RD) and mean diffusivity values in genu and splenium were observed over time, respectively. FA, RD, and mean diffusivity values continued to be abnormal in patients compared with controls at the end of 2 years. Although some NPT scores improved over time in these patients, these were still significantly impaired compared with controls.
CONCLUSIONS: FA and RD indices appear to be surrogate markers of microstructural alterations in patients over time and correlate significantly with some of the NPT scores. The recovery in these indices associated with recovery in neurocognitive deficits suggests that these indices may be used as an objective marker for residual injury in these patients.