When it comes to sports-related concussions, most of the attention goes toward football players, and for good reason. But ice hockey can be bad too. Players’ high speeds, the occasional fight, and body checking — a defensive move in which a player uses their body to knock their opponent away from the puck — may all contribute in some way to a concussion. Scientists have found that an already-effective brain imaging technique for concussion diagnosis can also be used to spot even smaller problems in a player’s brain, improving their doctor’s ability to make a diagnosis.

Because concussions can often be mild, with subtle symptoms, it’s easy for players to ignore the effects of a blow to the head. But hockey players suffer them, and often too. A report from the Institute of Medicine found that among women’s college sports, ice hockey had one of the highest concussion rates. These rates were also high in men’s college sports, along with football, lacrosse, and wrestling. Altogether, the report found that traumatic brain injuries (TBIs) in people 19 and younger had risen between 2001 and 2009 from 150,000 to 250,000.

With the help of a brain-imaging technique, known as susceptibility-weighted imaging (SWI), doctors have been able to diagnose more severe cases of TBI. SWI has the ability to produce high-resolution, 3D images of a person’s brain, with a specific sensitivity to their blood. By monitoring college-level ice hockey players for an entire season, they were able to spot small hemorrhages called cerebral microbleeds in the players’ brains. These microbleeds were considered hypointense, as bleeding looked worse in these areas when compared to the rest of the brain.

The researchers tested 25 men and 20 women before they started their season and then again at the end of their season. Athletes who suffered concussions during the season (five males and six females) were also tested with SWI 72 hours, two weeks, and two months after their injuries, while also undergoing clinical and neuropsychological exams. SWI results showed hypointense areas in all players at each checkup.

When the researchers looked to see who had suffered the most in terms of bleeding, they found that men who suffered concussions during their season showed significant differences two weeks after their injuries, when compared to their initial test. Women who had suffered concussions also showed some changes, though they weren’t statistically significant. Meanwhile, among players who hadn’t suffered concussions, the researchers still found that male players were a bit more likely to have hypointense areas at their end-of-study checkup than women.

Though there was no apparent reason for why men who hadn’t suffered concussions had hypointense areas, the researchers said that there was a chance some SWI readings could have been false positives. Still, they say that “data acquired using this method could be used for the monitoring of players throughout their careers and could lead to improved diagnoses and return-to-play guidelines,” according to a press release.

Concussions are typically minor TBIs caused by a blow to the head or vigorous shaking. It’s important that anyone who sustains one receives proper treatment and good rest due to the possibility of suffering another one, and risking permanent or fatal brain injury. Symptoms include headache, a temporary loss of consciousness, confusion; amnesia regarding the cause of the TBI, dizziness, and fatigue.

Source: Sasaki T, Pasternak O, Echlin P, et al. Hockey Concussion Education Project, Part 2. Microstructural white matter alterations in acutely concussed ice hockey players: a longitudinal free-water MRI study. Journal of Neurosurgery. 2014.