The aims of this study are:

1. to use delayed glymphatic clearance (GC)/capillary transit time (CTT) as a tool to measure change in brain function following acute traumatic brain injury (aTBI)

2. to assess whether flow improves when patients are cleared clinically to return to their respective sport.

Acute TBI is thought to accompany neuroinflammation with disruption of the blood-brain barrier (BBB) and GC/CTT. Currently, concussion is largely a clinical diagnosis utilizing subjective questionnaires as supplemental aids; however, 3D TGSE MRI PASL may serve as an objective way to assess brain health by measuring changes in GC. 

3D TGSE PASL MRI with long T1s was used to assess the clearance of ultra-filtered labeled protons 2800-4000 ms post-perfusion in frontal, temporal and parietal regions bilaterally following acute traumatic brain injury within 7 days of injury and when cleared to return to sport. The Sport Concussion Assessment Tool Version 5 (SKAT5) and Brief Oculomotor/Vestibular Assessment were used as cognitive adjuncts to MRI protocol. Subjects fulfilled the clinical diagnostic criteria for mild aTBI. 

Comparing intrasubject results at acute injury versus post-recovery, along with age-and-activity matched controls, we found reduced GC/CTT in select damaged brain regions. Although preliminary statistical analysis is pending, the reduction in clearance among post-aTBI groups based on current linear regression analysis presents a strong trend that will be explored further as we increase our sample size. 

Acute TBI disrupts the BBB and subsequently reduces GC/CTT, allowing inflammatory/toxic substances to remain in the neuropil. In this ongoing pilot study, we have observed reduced signal clearance in our concussive head trauma subjects compared to their recovery scan. This technique may provide a potentially reliable biomarker of acute changes and subsequent recovery following aTBI.