Hockey players who sustained concussions during a recent season experienced acute microstructural changes in their brains, according to a series of studies published in the Journal of Neurosurgery on Tuesday.

“We’ve seen evidence of chronic injuries later in life from head trauma, and now we’ve seen this in current players,” said Dr. Paul Echlin, an Ontario sports concussion specialist who conducted the study in collaboration with Dr. Martha Shenton of Brigham and Women’s Hospital and researchers from Harvard Medical School, Massachusetts General Hospital and Western University of Canada.

The researchers said these were the first studies in which an independent medical team used magnetic resonance imaging analysis before, during and after a season to measure the effects of concussions on athletes. Forty-five male and female Canadian university hockey players were observed by independent physicians during the 2011-12 season.

All 45 players were given M.R.I. scans before and after the season. The 11 who received a concussion diagnosis during the season were given additional scans within 72 hours, two weeks and two months of the incident.