Bidirectional Changes in Anisotropy Are Associated with Outcomes in Mild Traumatic Brain Injury

Abstract

Background and Purpose This prospective longitudinal study identifies early diffusion tensor imaging biomarkers of mild traumatic brain injury that significantly relate to outcomes at 1 year following injury. Materials and Methods DTI was performed on 39 mild traumatic brain injury subjects within 16 days of injury and 40 controls; 26 mild traumatic brain injury subjects returned for follow-up at 1 year. We identified subject-specific regions of abnormally high and low fractional anisotropy, and calculated mean fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity across all white matter voxels brain-wide, and across each of several white matter regions. Assessment of cognitive performance and symptom burden was performed at 1 year. Results Significant associations of brain-wide DTI measures and outcomes included: mean radial diffusivity and mean diffusivity with memory; mean fractional anisotropy, radial diffusivity and mean diffusivity with health-related quality of life. Significant differences in outcomes were found between subjects with and without abnormally high fractional anisotropy for the following white matter regions and outcome measures: left frontal lobe and left temporal lobe with attention at 1 year, left and right cerebelli with somatic post-concussion symptoms at 1 year, and right thalamus with emotional post-concussion symptoms at 1 year. Conclusion Individualized assessment of DTI abnormalities significantly relates to long-term outcomes in mild traumatic brain injury. Abnormally high fractional anisotropy is significantly associated with better outcomes, and might represent an imaging correlate of post-injury compensatory processes.

MRI-defined White Matter Microstructural Alteration Associated with Soccer Heading Is More Extensive in Women than Men

“…FA also increases in response to motor training of healthy adults, which suggests that it may be a manifestation of neuroplasticity (38). In addition, higher FA was recently reported as a predictor of better long-term outcome after recognized concussion, suggesting it may be indicative of compensatory change (39). In our study, participants had been exposed to years of repetitive subconcussive heading and, in some cases, periodic impacts of greater severity (ie, recognized concussion).…”

Preliminary evidence from a prospective DTI study suggests a posterior‐to‐anterior pattern of recovery in college athletes with sports‐related concussion

“…Substantial evidence by both research previously discussed and the current preliminary study supports the validity and importance of an individualized longitudinal approach with baseline measurements to manage concussion (Strauss et al, ). Despite the low subject number in our current study, the DTI data show promise in providing a sensitive method to temporally monitor brain regions which are vulnerable to concussive injury and to assess each athlete's individual path to recovery.…”

“…Using a baseline DTI scan greatly enhances detection of the ef- With these data from baseline, 2-day, 2-week, and 2-month scans, the current study was thus able to elucidate prefrontal WM as a brain region that exhibits pronounced increased diffusivity with prolonged variable recovery following concussion in athletes A recent longitudinal mTBI study that also utilized an individualized approach reported similar increases in RD and MD that additionally correlated with worse memory performance and worse somatic autonomy (Strauss et al, 2016). Interestingly, the authors suggest that increased RD may serve as a good early predictor of long-lasting dysfunction (Strauss et al, 2016). Even though post-injury FA abnormalities were also reported, all of the post-injury time points in the current study displayed insignificant FA results.…”

“…A recent longitudinal mTBI study that also utilized an individualized approach reported similar increases in RD and MD that additionally correlated with worse memory performance and worse somatic autonomy (Strauss et al, ). Interestingly, the authors suggest that increased RD may serve as a good early predictor of long‐lasting dysfunction (Strauss et al, ). Even though post‐injury FA abnormalities were also reported, all of the post‐injury time points in the current study displayed insignificant FA results.…”

BDNF Val66Met Positive Players Demonstrate Diffusion Tensor Imaging Consistent With Impaired Myelination Associated With High Levels of Soccer Heading: Indication of a Potential Gene-Environment Interaction Mechanism

“…A voxel-wise analysis of covariance (VANCOVA) was performed to identify subjectspecific abnormalities in DTI parameters including Fractional Anisotropy (FA), Radial Diffusivity (RD), Axial Diffusivity (AD), and Mean Diffusivity (MD). As previously described (26,27), this is a method that permits us to identify clusters (e.g., a grouping of voxels) of DTI abnormalities by comparing each individual subject to a group of normative controls. In the present study, DTI parameter image volumes from each soccer player were compared to those of 110 healthy controls to identify subjectspecific abnormalities in DTI parameters.…”