Serial Diffusion Kurtosis Magnetic Resonance Imaging Study during Acute, Subacute, and Recovery Periods after Sport-Related Concussion

Abstract

Sport-related concussion (SRC) is common in contact sports, but there remains a lack of reliable, unbiased biomarkers of brain injury and recovery. Although the symptoms of SRC generally resolve over a period of days to weeks, the lack of a biomarker impairs detection and return-to-play decisions. To this date, the pathophysiological recovery profile and relationships between brain changes and symptoms remained unclear. In the current study, diffusion kurtosis imaging (DKI) was used to monitor the effects of SRC on the brain and the trajectory of recovery in concussed American football players (n = 96) at <48 h, and 8, 15, and 45 days post-injury, who were compared with a matched group of uninjured players (n = 82). The concussed group reported significantly higher symptoms within 48 h after injury than controls, which resolved by the 8-day follow-up. The concussed group also demonstrated poorer performance on balance testing at <48 h and 8 days than controls. There were no significant differences between the groups in the Standardized Assessment of Concussion (SAC), a cognitive screening measure. DKI data were acquired with 3 mm isotropic resolution, and analyzed using tract-based spatial statistics (TBSS). Additionally, voxel-and region of interest-based analyses were also conducted. At <48 h, the concussed group showed significantly higher axial kurtosis than the control group. These differences increased in extent and magnitude at 8 days, then receded at 15 days, and returned to the normal levels by 45 days. Kurtosis fractional anisotropy (FA) exhibited a delayed response, with a consistent increase by days 15 and 45. The results indicate that changes detected in the acute period appear to be prolonged compared with clinical recovery, but additional brain changes not observable acutely appear to progress. Although further studies are needed to understand the pathological features of DKI changes after SRC, these findings highlight a potential disparity between clinical symptoms and pathophysiological recovery after SRC.

Acute Diffusion Tensor and Kurtosis Imaging and Outcome following Mild Traumatic Brain Injury

“…These findings are in line with a few previous studies reporting that DKI was superior to DTI in detecting deviations in white matter in the acute to chronic phase after MTBI. 33,35 The present results add to this literature by showing that although DKI metrics were affected acutely by the MTBI, the DTI metrics were more closely related to PPCS development.…”

“…In previous subacute and chronic studies, it varies in which white matter tracts differences are observed, but differences in these tracts, especially in the corpus callosum, are commonly reported. 5,6,9,10,12,52 In contrast to studies on mixedmechanism MTBI, studies on sports-related concussion have acquired acute MRI more frequently, and a few studies have reported associations between higher MD, AD and RD and symptoms, 53,54 but a lack of associations has also been reported 35,55 However, the symptoms were also assessed acutely in most studies on sports-related concussion, which makes it difficult to directly compare these findings with ours. Moreover, the variability in both age and injury mechanism is considerably larger in mixed-mechanism studies.…”

“…DKI does not assume a Gaussian distribution of diffusion and may be superior in identifying microstructural abnormalities in areas with high heterogeneity. 26,27 Deviating DKI metrics have been reported in both white and gray matter, in the acute to chronic phase following MTBI, [28][29][30][31][32][33][34][35] but the association between DKI metrics and PPCS is unclear. 15,32,34,35 To fill these knowledge gaps, the current study includes a large representative sample of patients with mixed-mechanism MTBI who underwent both DTI and DKI in the acute phase.…”

“…26,27 Deviating DKI metrics have been reported in both white and gray matter, in the acute to chronic phase following MTBI, [28][29][30][31][32][33][34][35] but the association between DKI metrics and PPCS is unclear. 15,32,34,35 To fill these knowledge gaps, the current study includes a large representative sample of patients with mixed-mechanism MTBI who underwent both DTI and DKI in the acute phase. 36,37 The aim was to compare diffusion metrics between patients who later developed PPCS, patients without PPCS, and healthy controls; (1) in the total sample, (2) in patients with uncomplicated MTBI, and (3) with cognitive reserve both controlled for and not.…”

“… 26 , 27 Deviating DKI metrics have been reported in both white and gray matter in the acute to chronic phase following mTBI, 28–35 but the association between DKI metrics and PPCS is unclear. 15 , 32 , 34 , 35 …”