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Modified dynamic contrast-enhanced MRI can pinpoint a leaky blood-brain barrier in both active and retired players.
A new MRI test could completely change the diagnosis of a neurodegenerative disease in football players. Rather than only being identifiable after death, this newly developed technique can pinpoint the characteristics of chronic traumatic encephalopathy (CTE) in younger players, many of whom are still actively playing the game.
The hallmark characteristic of CTE is a leaky blood-brain barrier frequently caused by repeated head injuries due to the impacts experienced in contact sports. Once the blood-brain barrier has been breached, it can allow unwanted molecules and infectious organisms that circulate in the bloodstream to infiltrate the brain, potentially leading to brain diseases and neurodegeneration associated with aging.
In a study published in Brain, a Journal of Neurology, investigators from Ben-Gurion University of Negev in Israel detailed the results of their work, using modified dynamic contrast-enhanced MRI (DCE-MRI) to examine the vascular pathology and blood-brain barrier disorder typically found with repeated, mild traumatic brain injuries in football players.
“Since a leaky [blood brain barrier] is also found in CTE and causes brain dysfunction and degeneration, it now seems that this test could provide the first (and so far only) evidence for brain injury in the players we studied on the Israel football team,” said Alon Friedman, M.D., a neurosurgeon and researcher at Ben-Gurion University of the Negev (BGU) and Dalhousie University in Canada.
This is the first time, using human brain imaging, that researchers have been able to differentiate between fast and slow leakage in the blood-brain barrier. This is particularly important, Friendman’s team said, because the imaging shows that localized, specific post-traumatic vascular pathology can continue for months in some players – and those individuals are more likely to develop CTE. Those whose blood-brain barriers heal quickly – or those who do not experience repeated head injuries – are less at risk.
To test the efficacy for DCE in identifying any blood-brain barrier leaks, the investigative team enrolled and gathered MRI images on 42 Israeli football players who played amateur American football in the Israeli Football League, as well as 27 athletes in non-contact sports, and 26 non-athletes. In addition, 51 patients with malignant brain tumors, ischemic stroke or traumatic brain injury also received MRI scans. Researchers used the National Football League concussion assessment tool to document any previous head injuries, such as concussions, and to assess symptoms.
“We generated maps that visualized the permeability value for each 3D section (voxel). Our permeability maps revealed an increase in slow blood-to-brain transport in a subset of amateur American football players, but not in the control group,” Friedman said. “The increase in permeability was region specific (white matter, midbrain peduncles, red nucleus, temporal cortex) and correlated with alterations in white matter tracts. Importantly, increased permeability persisted for months, as seen in players who were scanned both on-and-off season.”
Based on their results, the team determined that football players were three times more likely to display a leaky blood-brain barrier than the other study participants. Of that group, the investigators detected blood-brain barrier disorder in 27.4 percent of players. The variability, the team said, could explain the wide variety of cognitive deficits and neuropsychiatric impairments seen in players, possibly reflecting differences in affected brain networks.
It was also significant, they said, that even a few players who did not complain about severe symptoms showed a leaky blood-brain barrier, suggesting that DCE-MRI should be used alongside symptom questionnaires before players are cleared to return to play, they said.
“Our findings show that DCE-MRI can be used to diagnose specific vascular pathology after traumatic brain injury and other brain pathologies,” Friedman said.
Overall, the team said, future studies should be conducted to pinpoint the prevalence and spatial-temporal characteristics of the blood-brain barrier disorder in both professional and retired players with or without CTE signs and symptoms. Any identified differences, they said, could augment how well providers understand the effects of impact strength and frequency, age of onset, player’s skill and extent of vascular injury.