Delay in Clearance of Labeled Protons Post Acute Head Trauma Utilizing 3D ASL MRI (Arterial Spin Labeling) a Pilot Study

Abstract This study correlated mild traumatic brain injury (mTBI) cognitive changes with ASL-MRI glymphatic clearance rates (GCRs) and recovery with GCR improvement. . mTBI disrupts the blood brain barrier (BBB), reducing capillary mean transit time (cMTT) and GCRs. mTBI is clinically diagnosed utilizing history/examination findings with no physiologic biomarkers. 3D TGSE (turbo-gradient spin-echo) PASL (pulsed arterial spin-labeling) 3T MRI with 7 long TIs (inversion times) assessed the signal clearance of labeled protons 2800-4000 ms postlabeling in bifrontal, bitemporal, and biparietal regions within 7 days of mTBI and once clinically cleared to resume activities. The Sport Concussion Assessment Tool Version 5 (SKAT5) and Brief Oculomotor/Vestibular Assessment evaluated injured athletes’ cognitive function prior to MRIs. The pilot study demonstrated significant GCRs improvement (95% [CI] -0.06 to -0.03 acute phase; to [CI] - recovery [CI] 0.0772 to -0.0497; P <0.001 in frontal lobes; and parietal lobes (95% [CI] -0.0584 to -0.0251 acute; [CI] -0.0727 to -0.0392 recovery; P = 0.024) in 9 mTBI athletes (8 female, 1 male). Six age/activity-matched controls (4 females, 2 males) were also compared. mTBI disrupts the BBB, reducing GCR measured using the 3D ASL MRI technique. ASL MRI is a potential noninvasive biomarker of mTBI and subsequent recovery.