Daily Bulletin 2015

MRI Technique Shows Link to Osteoarthritis in College Football Players

Thursday, Dec. 03, 2015

Wenbo Wei, Ph.D.

Wenbo Wei, Ph.D.

Using delayed Gadolinium-enhanced MRI of Cartilage (dGEMRIC) on knee cartilage shows that playing collegiate football for a longer period of time may lead to microstructural damage that is an indicator of osteoarthritis (OA), a researcher said at a Wednesday presentation.

The findings of the study demonstrate that dGEMRIC is capable of assessing glycosaminoglycan (GAG) loss within each individual articular cartilage region as well as the gradual changes related to the cumulative years of playing collegiate football, said presenter Wenbo Wei, Ph.D., of Ohio State University.

"This pilot study was important because we found the earliest indicator of OA," Dr. Wei said. "The athletes are young, and they have something they can do about it."

Dr. Wei scanned the knees of 13 college football players before and after each season, finding that small changes occurred during the season but greater micro-architectural changes occurred over the course of a few years.

"We think this is because during the season, they are just playing football games, but during offseason there is all sorts of training and exercise," Dr. Wei said, adding that the study did not scan more frequently in order to minimize the test subjects' dose exposure.

At the pre-season, first-year college football players averaged a 0.116 mM contrast concentration before the season and increased to 0.117 mM average post-season, with the higher concentrations indicating a greater GAG loss. In players with more years of experience, there was a 20 percent higher concentration. The average contrast concentration was 0.139 mM preseason and 0.140 mM postseason.

"I'm not surprised by the finding. They train a lot and in football you have a lot of collisions," Dr Wei said. "It's reasonable that you would have some micro-architectural changes."

The decreased GAG concentration may be indicative of a higher risk factor for articular cartilage degradation and potential development of OA. OA is of particular interest in sports medicine as studies have found that the condition impacts 36 percent of athletes compared to 5 percent of the general population, Dr. Wei said.

Although the study aggregated the concentration measurements into an average, the scan protocol measured several regions of the knee. The most significant differences between the single-year players and the multiple-year players were shown at the trochlea and carpometacarpal joint dislocation at the post-season, Dr. Wei said.

Dr. Wei used the dGEMRIC technique because it is considered the "gold standard in assessing GAG concentration in vivo." Using a Gd-DTPA2 contrast agent is key to the technique because its negative charge is similar to the cartilage matrix and thus distributes more effectively into areas of cartilage that are depleted of GAG. Also, Gd-DTPA2- shortens the magnetic resonance relaxation time, he said.

Two musculoskeletal radiologists with eight and seven years of experience independently evaluated athletes' articular cartilage for any focal lesions. Cartilage lesions were graded on the Outerbridge classification system.

Dr. Wei acknowledged the study's small sample size (seven were one-year players and six had played two-to-four seasons.), but feels he demonstrated that OA risk factors can be found in college-age athletes. He plans to collect more data, but the next research stage will focus on college-age students who are not athletes in order to establish a control group.

Question of the Day:

The headphones patients usually wear while undergoing an MRI don't fit under our new head coil. Can I scan patients safely without them?

Tip of the day:

Power Doppler ultrasound can be used to image low-flow shallow vessels because it is independent of flow direction and angle.

The RSNA 2015 Daily Bulletin is owned and published by the Radiological Society of North America, Inc., 820 Jorie Blvd., Oak Brook, IL 60523.