Fan-pei Gloria Yang1, Charvi Shetty1, Hana Lee1, Sara Lahue1, Shelly Cooper1, Chirstopher Nguyen1, Mehul Sampat1, Jamshid Ghajar2, Geoffrey Manley3,4, Sandya Venugopal1, Pratik Mukherjee1,4
1Radiology & Bioengineering, University of California San Francisco, San Francisco, CA, USA; 2Brain Trauma Foundation, New York, USA; 3Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA; 4Brain & Spinal Injury Center, University of California San Francisco, USA
Diffusion tensor imaging (DTI) shows promise in mild TBI patients as a biomarker for neurocognitive outcome. However, using diffusion tensor imaging for prognosis remains controversial because recent studies of the early phase of mild traumatic brain injury have shown conflicting results. Furthermore, there is a lack of prior longitudinal DTI studies of mild head trauma. We used tract-based spatial statistics (TBSS), a whole-brain data-driven diffusion tensor analysis method, to examine microstructural white matter changes measured within 2 weeks, at 1 month, and at 1 year after mild head trauma with loss of consciousness and post-traumatic amnesia, with correlation to performance on tests of verbal memory and visuospatial attention. Thirty adult patients were compared with 29 controls matched for age, gender, and level of education. Following brain extraction, motion correction, and generation of DTI parametric maps using the tools provided in FSL, the voxel-wise statistical analysis of DTI parameter maps was conducted with TBSS.Multiple comparison correction was conducted with Threshold-Free Cluster Enhancement (TFCE) in Randomise. Widespread decreases of FA and increases of mean diffusivity and radial diffusivity were found in patients versus controls at the early time point. The loss of white matter FA was progressive over time, worsening both in magnitude and spatial extent across the three time points. The left and right anterior corona radiata showed the greatest early reduction in FA, with values in the right anterior corona radiata strongly correlating with verbal memory performance. We also demonstrate that early FA measurements in the right superior longitudinal fasciculus predict long-term outcome on visuospatial attention testing. Finally, those patients whose verbal memory did not improve during the first year after injury showed greater and more widespread decreases compared to controls in white matter FA, measured at the early time point, than did those patients whose verbal memory did improve over the three time points.