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J Neurosurg. 2018 Apr 1:1-9. doi: 10.3171/2017.12.JNS171597. [Epub ahead of print]

Prospective study of myelin water fraction changes after mild traumatic brain injury in collegiate contact sports.

Author information

1Division of Pediatric Neurosurgery, Joe DiMaggio Children's Hospital, and.
2Waisman Center, University of Wisconsin-Madison, Wisconsin.
3Division of Neuropsychiatry and Behavioral Neurology.
5Department of Neurology, and.
6Department of Emergency Medicine, and.
10Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
8Office of Human Research, Memorial Healthcare System, Hollywood, Florida.
7Department of Diagnostic Imaging, Rhode Island Hospital.
4Department of Psychiatry and Human Behavior.
9Providence VA Medical Center, Providence; and.
11Advanced Baby Imaging Lab, School of Engineering, Brown University; and.
12Department of Pediatrics, Memorial Hospital of Rhode Island, Pawtucket, Rhode Island; and.


OBJECTIVEMild traumatic brain injury (mTBI) in athletes, including concussion, is increasingly being found to have long-term sequelae. Current imaging techniques have not been able to identify early damage caused by mTBI that is predictive of long-term symptoms or chronic traumatic encephalopathy. In this preliminary feasibility study, the authors investigated the use of an emerging magnetic resonance imaging (MRI) technique, multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT), in visualizing acute and chronic white matter changes after mTBI in collegiate football and rugby players.METHODSThis study was a nonrandomized, nonblinded prospective trial designed to quantify changes in the myelin water fraction (MWF), used as a surrogate MRI measure of myelin content, in a group of male collegiate football and rugby players, classified here as a contact sport player (CSP) cohort, at the time of mTBI diagnosis and 3 months after injury when the acute symptoms of the injury had resolved. In addition, differences in the MWF between the CSP cohort and a control cohort of noncontact sport players (NCSPs) were quantified. T-tests and a threshold-free cluster enhancement (TFCE) statistical analysis technique were used to identify brain structures with significant changes in the MWF between the CSP and NCSP cohorts and between immediately postinjury and follow-up images obtained in the CSP cohort.RESULTSBrain MR images of 12 right-handed male CSPs were analyzed and compared with brain images of 10 right-handed male NCSPs from the same institution. A comparison of CSP and NCSP baseline images using TFCE showed significantly higher MWFs in the bilateral basal ganglia, anterior and posterior corpora callosa, left corticospinal tract, and left anterior and superior temporal lobe (p < 0.05). At the 3-month follow-up examination, images from the CSP cohort still showed significantly higher MWFs than those identified on baseline images from the NCSP cohort in the bilateral basal ganglia, anterior and posterior corpora callosa, and left anterior temporal lobe, and also in the bilateral corticospinal tracts, parahippocampal gyrus, and bilateral juxtapositional (previously known as supplemental motor) areas (p < 0.05). In the CSP cohort, a t-test comparing the MWF at the time of injury and 3 months later showed a significant increase in the overall MWF at follow-up (p < 0.005). These increases were greatest in the bilateral basal ganglia and deep white matter. MWF decreases were seen in more superficial white matter (p < 0.005).CONCLUSIONSIn this preliminary study, MWF was found to be increased in the brains of CSPs compared with the brains of controls, suggesting acute/chronic MWF alterations in CSPs from previous injuries. Increases in the MWF were also demonstrated in the brains of CSPs 3 months after the players sustained an mTBI. The full clinical significance of an increased MWF and whether this reflects axon neuropathology or disorderly remyelination leading to hypermyelination has yet to be determined.


ASL = arterial spin labeling; CSP = contact sport player; CTE = chronic traumatic encephalopathy; DTI = diffusion tensor imaging; FA = fractional anisotropy; FLAIR = fluid-attenuated inversion recovery; FWE = familywise error; IR-SPGR = inversion recovery-spoiled gradient recalled echo sequence; MCR = multicomponent relaxation; MP-RAGE = magnetization prepared rapid acquisition gradient echo; MWF = myelin water fraction; NCSP = non-CSP; SSFP = steady-state free precession; SWI = susceptibility weighted imaging; TFCE = threshold-free cluster enhancement; concussion; mTBI = mild traumatic brain injury; mcDESPOT = multicomponent driven equilibrium single pulse observation of T1 and T2; mild traumatic brain injury; myelin; sports


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