To compare preseason and post-concussive MRI in a cohort of collegiate football players utilizing Diffusion Tensor Imaging (DTI) and Neurite Orientation Dispersion and Density Imaging (NODDI) post processing.

Acute post-concussive symptoms can vary in clinical characteristics and severity. However, vestibular and ocular dysfunction in particular, has been associated with poor clinical outcomes.  The vestibular system comprises a complex network of projections from peripheral vestibular organs to thalamic relay systems and numerous cortical regions. The visual/oculomotor system is also complex, involving brainstem, subcortical-cortical and thalamo-cortical connections. Oculomotor deficits are thought to involve the midbrain and the visual and parietal association cortices, both of which have thalamic projections.

We gathered pre-season MR diffusion weighted imaging on a cohort of 30 collegiate football players. We performed repeat imaging within 36 hours of any diagnosed concussion in the same subject cohort. DTI metrics:  mean diffusivity (MD), axial diffusivity (AD), fractional anisotropy (FA), and radial diffusivity (RD) along with NODDI metric: orientation dispersion index (ODI), were analyzed for statistical comparisons between groups.  

4 subjects with pre-season MRI underwent repeat MRI within 36 hours of concussive injury.  A paired t-test between these two groups using DTI and NODDI metrics showed significant (p<0.05) decreases in: AD and MD in the left posterior thalamic radiations, FA in the column and body of the fornix, and MD in the right anterior corona radiata and superior fronto-occipital fasciculus, and a significant decrease in ODI in the anterior thalamus.

Disruptions in the thalamus and its white matter projections may play a role in the vestibular/ocular dysfunction associated with acute concussive injury.  While our numbers are small, the findings suggest that DTI and NODDI processing techniques have the capability to locate and measure grey and white matter injury patterns after concussive injury.