LAUSR

The purpose of this study is to assess the relationship between regional white matter diffusion imaging metrics and finite element strain measures in non-concussed youth football players. Pre and postseason diffusion-weighted imaging was performed in 102 youth football subject-seasons, in which no concussions were diagnosed. The diffusion data was normalized to the IXI template. Percent change in fractional anisotropy FA (%ΔFA) images were generated. Using data from the head impact telemetry system, the cumulative maximum principal strain 1 times strain rate (CMPS1xSR), a measure of the cumulative tensile brain strain and strain rate for one season, was generated for each subject. Two linear regression analyses were performed to identify significant positive or inverse relationships between CMPS1xSR and %ΔFA within the international consortium for brain mapping white matter mask. Age, BMI, days between pre and postseason imaging, prior brain injury, attention disorder diagnosis, and imaging protocol were included as covariates. False discovery rate correction was used with corrected alphas of 0.025 and voxel thresholds of zero. Controlling for all covariates, a significant, positive linear relationship between %ΔFA and CMPS1xSR was identified in the bilateral cingulum, fornix, internal capsule, external capsule, corpus callosum, corona radiata, corticospinal tract, cerebral and middle cerebellar peduncle, superior longitudinal fasciculus, and right superior fronto-occipital fasciculus. Post-hoc analyses further demonstrated significant %ΔFA differences between high-strain football subjects and non-collision control athletes, no significant %ΔFA differences between low-strain subjects and non-collision control athletes, and that CMPS1xSR significantly explained more %ΔFA variance than number of head impacts alone. In the absence of clinically diagnosed concussion, youth football players experience regional, dose-dependent white matter FA increases that are significantly associated with CMPS1xSR.