In the Game
As sports concussions gain more attention, radiologists dive in to help prevent further injuries.
Anyone who's been to a football game knows the sound of helmet meeting helmet, an icy and distinct "crack." Some spectators feel energized by the sport's telltale soundtrack as they anticipate mind-blowing plays and complex strategies.
But a growing number of other individuals cringe as such violence conjures images of athletes disabled after too many concussions on the field.
And they have good reason to be uncomfortable. Despite recent estimates that as many as 3.8 million concussions occur annually in U.S. sports, much is unknown about this mild traumatic brain injury (TBI).1 Moreover, it's often difficult to tell via imaging whether a concussion has occurred. "Usually, MRIs and CTs are normal [in the case of a suspected concussion]," says Michael Zeineh, MD, PhD, neuroradiologist and assistant professor of radiology at Stanford University in Stanford, Calif.
Evaluating Long-Term Issues
Even less is known about the long-term effects of repeated concussions, which have received the bulk of recent media attention. According to an article in Brain Imaging and Behavior, "Effects of mild TBI have been linked to several neurologic and mental health disorders later in life crossing the spectrum from Alzheimer's disease, chronic traumatic encephalopathy, post-traumatic stress disorder, substance abuse, and anxiety and depression leading to suicide."1 These concerns have been highlighted by the 2,000 former NFL players who recently filed lawsuits against the NFL, claiming the organization "withheld information related to head trauma suffered while playing the game."2
With such dire ailments potentially on the horizon for concussed patients, radiologists and physicians from other specialties have dived into this relatively underexplored research topic. "It's an important area of research; there are a lot of concussions in high school and college athletes. We'd like to see if there are abnormalities present that we're not detecting," says Zeineh, who is part of the Head Injury Prevention Program at Stanford. "We'd like to advance our knowledge of MR techniques to improve the accuracy of the diagnosis."
Working With Student Athletes
Ultimately, the hope is to create an unbiased, quantitative measure of concussion risk and severity. "I think this would be tremendously beneficial to identify injured student athletes and to prevent worsening of their neurological status, such as in the case of second-impact syndrome," says Huy Do, MD, associate professor of radiology, and Zeineh's colleague in the Head Injury Prevention Program at Stanford. Second-impact syndrome occurs when a concussed individual receives a second blow to the head before the initial concussion has properly healed. Such an injury can be fatal.
The Head Injury Prevention Program is a multidisciplinary project at Stanford that studies the university's student athletes over their collegiate sports careers — imaging is just one piece; clinical criteria, plasma biomarkers, and neuropsychological effects make up other areas of the investigation. "This hasn't really been done before," says Do. "We're not only looking at imaging, but also metabolic and plasma biomarkers involved in mild TBI." Number one on their priority list is to offer a universal clinical definition of a concussion. "Different academic societies have different definitions. Even the NFL has its own," Do adds.
Do and Zeineh started their research on this year's freshman football players as well as athletes in other sports. All participants receive a baseline MR exam, a process that will be repeated throughout their sports career at Stanford. "Our goal will be mainly to correlate imaging findings with symptoms and determine what caused what symptom," says Do. "What we're doing is really important to objectively diagnose a concussion, so there's no ambiguity on how to take care of these young athletes."
Preferred Imaging Methods
But if CT and MRI exams are often normal in suspected cases of concussion, what is the best imaging method to diagnose such a mild TBI? "Just because a CT is normal does not mean that the brain did not sustain a concussion," says Pratik Mukherjee, MD, PhD, associate professor of radiology and bioengineering at the University of California at San Francisco. "Using 3T MRI, you may be able to find evidence of structural injury. And even if you can't identify that, there may be functional or microstructural damages that wouldn't be apparent except in the more advanced diffusion tensor imaging or perhaps resting-state functional MRI."
Perhaps if those imaging techniques can identify damages caused by a mild TBI, they can also assist in answering another controversial question: what constitutes complete recovery from a concussion? According to the Brain Imaging and Behavior article, "There is still a lack of belief among neuropsychological and clinical researchers that concussion results in long-lasting structural injury to the neuron. This idea is reflected in the sentiment of nearly every consensus statement on concussion."1 The authors also point out that many consensus statements by these researchers include observations that "concussion may result in neuropathologic changes, but the clinical symptoms largely reflect a functional disturbance rather than a structural injury."
And though it's difficult to determine structural injury using current imaging techniques, Mukherjee is optimistic about future methods. "There's not going to be any one imaging technique [to diagnose a concussion or determine abnormalities]," says Mukherjee. "Some more promising avenues include high-field MRI, and I think 3T and above MRI will eventually become the standard used to evaluate patients with mild TBI."
Attracting Media and Legal Attention
Though imaging is a critical piece of the clinical puzzle, much information can be gained after an athlete's death. In February 2011, 50-year-old Dave Duerson, former NFL player, died after shooting himself in the chest. Police on the scene found a note from Duerson, asking that his "brain be given to the NFL's brain bank." He hoped that a postmortem exam of his brain would confirm his suspicions — that he suffered from chronic traumatic encephalopathy (CTE). The "brain bank," which studies the brains of deceased athletes, is part of Boston University's Center for the Study of Traumatic Encephalopathy and is funded, in part, but the NFL. Researchers at the center validated Duerson's self-diagnosis.
Studying the brains of deceased veteran players is expected to yield valuable findings, but what about the 18-year-old boy who died after playing football for "a couple of years"? When the young athlete's brain was examined, researchers found large amounts of tau — a protein that can build up over time and ultimately kill brain cells. And it's a key ingredient in the development of Alzheimer's disease. One of the article's sources, Ann McKee, MD, who runs the neuropathology lab at the Veteran's Hospital in Bedford, Mass., says, "You don't see tau like this in an 18-year-old. You don't see tau like this in a 50-year-old."
But these are just two stories in a sea of many others, and the media has latched onto these devastating tales. It's no surprise, then, that the NFL recently announced it would donate $30 million to NIH for medical research. Exact plans are under development, but potential research areas include CTE, concussion management and treatment, and the relationship between TBIs and long-term disorders.
"This is a hot-button for society," says Do. And as hot-button topics often do, this one questions legal responsibility. Whose fault is it when a former football player develops dementia at age 65?
"We as radiologists might be called into lawsuits to testify whether a trauma caused a specific abnormality in the brain," Do says. However, Zeineh notes that testifying as to whether the abnormality in question is specifically related to a singular concussion is a little more speculative. "Did the concussion cause 'X'? Sometimes people have incidental findings in imaging, and we don't know if they're related [to a concussion]," he says.
Reliably relating abnormalities to concussions is perhaps a long way off because, as Do notes, "We're just beginning to get an inkling of how multiple concussive hits impact the rest of someone's life." As for the Head Injury Prevention Program, Do and Zeineh hope to have useful data in 5 to 10 years. After all, this is not a sprint, but a marathon. And for football as a whole, Do has this to say: "I don't think anyone wants to get rid of the NFL. But maybe we can make it safer for our children and grandchildren."
1. Slobounov S, Gay M, Johnson B, Zhang K. “Concussion in Athletes: Ongoing Clinical and Brain Imaging Research Controversies.” Brain Imaging and Behavior. June 2012;6:224–43.
2. Maese R. “Players Come Together to Take on NFL.” The Washington Post. June 7, 2012.
By Raina Keefer