Abnormalities in diffusional kurtosis metrics related to head impact exposure in a season of high school varsity football

Elizabeth M. Davenport, Kalyna Apkarian, Christopher T. Whitlow, Jillian E. Urban, Jens H. Jensen, Eliza Szuch, Mark A. Espeland, Youngkyoo Jung, Daryl A. Rosenbaum, Gerard A. Gioia, Alexander K. Powers, Joel D. Stitzel, Joseph A Maldjian

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


The purpose of this study was to determine whether the effects of cumulative head impacts during a season of high school football produce changes in diffusional kurtosis imaging (DKI) metrics in the absence of clinically diagnosed concussion. Subjects were recruited from a high school football team and were outfitted with the Head Impact Telemetry System (HITS) during all practices and games. Biomechanical head impact exposure metrics were calculated, including: Total impacts, summed acceleration, and Risk Weighted Cumulative Exposure (RWE). Twenty-four players completed pre- and post-season magnetic resonance imaging, including DKI; players who experienced clinical concussion were excluded. Fourteen subjects completed pre- and post-season Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). DKI-derived metrics included mean kurtosis (MK), axial kurtosis (K axial), and radial kurtosis (K radial), and white matter modeling (WMM) parameters included axonal water fraction, tortuosity of the extra-axonal space, extra-axonal diffusivity (De axial and radial), and intra-axonal diffusivity (Da). These metrics were used to determine the total number of abnormal voxels, defined as 2 standard deviations above or below the group mean. Linear regression analysis revealed a statistically significant relationship between RWE combined probability (RWECP) and MK. Secondary analysis of other DKI-derived and WMM metrics demonstrated statistically significant linear relationships with RWECP after covariate adjustment. These results were compared with the results of DTI-derived metrics from the same imaging sessions in this exact same cohort. Several of the DKI-derived scalars (Da, MK, K axial, and K radial) explained more variance, compared with RWECP, suggesting that DKI may be more sensitive to subconcussive head impacts. No significant relationships between DKI-derived metrics and ImPACT measures were found. It is important to note that the pathological implications of these metrics are not well understood. In summary, we demonstrate a single season of high school football can produce DKI measurable changes in the absence of clinically diagnosed concussion.

Original languageEnglish (US)
Pages (from-to)2133-2146
Number of pages14
JournalJournal of neurotrauma
Issue number23
StatePublished - Dec 1 2016


  • Head Impact Telemetry System
  • Risk Weighted Cumulative Exposure
  • concussion
  • diffusion kurtosis imaging
  • football

ASJC Scopus subject areas

  • Clinical Neurology


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