It is important to understand the potential changes occurring in the
brain related to youth contact sports. Brain imaging exams performed on high school football players after
just one season revealed changes in both the gray and white matter that
correlated with exposure to head impacts, revealed a new study.
The findings will be presented at the annual meeting of the Radiological
Society of North America (RSNA).
‘Structural and functional imaging studies among high school football players revealed changes in both the gray and white matter after just one season.’
Elizabeth Moody Davenport,
a postdoctoral researcher at UT Southwestern Medical Center in
Dallas, Texas, who led this analysis, said, "We know that some professional
football players suffer from a serious condition called chronic
traumatic encephalopathy, or CTE. We are attempting to find out when and
how that process starts, so that we can keep sports a healthy activity
for millions of children and adolescents."
The study included 24 players from a high school football team in
North Carolina, each of whom wore a helmet outfitted with the Head
Impact Telemetry System (HITS) during all practices and games. The
helmets are lined with six accelerometers, or sensors, that measure the
magnitude, location and direction of a hit. Data from the helmets can be
uploaded to a computer for analysis.
"We saw changes in these young players' brains on both structural
and functional imaging after a single season of football," Dr. Davenport
In the study, each player underwent pre- and post-season imaging: a
specialized MRI scan, from which diffusion tensor imaging (DTI) and
diffusion kurtosis imaging (DKI) data were extracted to measure the
brain's white matter integrity, and a magnetoencephalography (MEG) scan,
which records and analyzes the magnetic fields produced by brain waves.
Diffusion imaging can measure the structural white matter changes in
the brain, and MEG assesses changes in function.
"MEG can be used to measure delta waves in the brain, which are a
type of distress signal," Dr. Davenport said. "Delta waves represent
slow wave activity that increases after brain injuries. The delta waves
we saw came from the surface of the brain, while diffusion imaging is a
measure of the white matter deeper in the brain."
The research team calculated the change in imaging metrics between
the pre- and post-season imaging exams. They measured abnormalities
observed on diffusion imaging and abnormally increased delta wave
activity on MEG. The imaging results were then combined with
player-specific impact data from the HITS. None of the 24 players were
diagnosed with a concussion during the study.
Players with greater head impact exposure had the greatest change in diffusion imaging and MEG metrics.
"Change in diffusion imaging metrics correlated most to linear
acceleration, similar to the impact of a car crash," Dr. Davenport said.
"MEG changes correlated most to rotational impact, similar to a boxer's
punch. These results demonstrate that you need both imaging metrics to
assess impact exposure because they correlate with very different
Dr. Davenport said similar studies are being conducted this fall,
and a consortium has been formed to continue the brain imaging research
in youth contact sports across the country.
"Without a larger population that is closely followed in a
longitudinal study, it is difficult to know the long-term effects of
these changes," she said. "We don't know if the brain's developmental
trajectory is altered, or if the off-season time allows for the brain to
return to normal."