FRIDAY, Oct. 7 (HealthDay News) -- Exposing children to MRIs during pediatric clinical trials is not unduly risky to their well-being as long as sedation and injectable dyes aren't used, new Canadian research concludes.

The study finds that MRIs, when used without additional intravenous contrast dyes or sedation, pose no greater physical or psychological harm to healthy children than routine activities such as playing sports or riding in a car.

However, injectable contrast dyes, which are used to improve scan resolution, may pose an unreasonable allergic-reaction risk that is greater than that posed by, for example, routine vaccinations, the researchers found.

Similarly, using sedation during imaging sessions appears to raise the risk for side effects, such as gastrointestinal issues and motor imbalance, to a level considered unsafe for children.

Lead author Dr. Matthias H. Schmidt, an associate professor in the department of radiology at Dalhousie University in Halifax, Nova Scotia, reported his team's findings in the September/October issue of IRB: Ethics & Human Research.

Schmidt and his colleagues noted that research ethics review boards have long struggled with the question of MRI safety in the context of pediatric research.

The team thus set out to establish so-called "minimal-risk standards" for pediatric imaging exposure safety by analyzing a range of information, including MRI safety data collected by the U.S. Food and Drug Administration's "Manufacturer and User Facility Device Experience."

The bottom-line: Ice hockey and soccer pose as much, if not more, risk for physical injury to children as MRIs.

While the risk for physical injury to children posed by an hour-long MRI is 17 for every 100,000 imagings, the risk for injury is as high as 12,730 for every 100,000 hours a child under the age of 16 plays ice hockey, the study found.

Similarly, the risk of dying from an MRI scan (four for every 100 million scans) is much less than the risk of dying in a car accident (six for every 100 million car trips for children 14 and under and 40 per hundred million rides for teens 15 to 19), the study revealed.

Also, the risk of suffering psychological hardship, such as claustrophobia and/or noise disturbances, appeared to be greater among children struggling with anxiety disorders than it did among those exposed to an MRI.

But the MRI-associated chance that a child would develop either gastrointestinal issues (an 18 to 37 percent risk) or motor imbalance (a 66 to 85 percent risk) was deemed to be above reasonable safety standards.

And use of a contrast dye appeared to unduly raise the risk for developing a fever, headache or an anaphylaxis reaction.

The team therefore concluded that while MRIs themselves are safe for children in a clinical trial setting, the use of contrast dyes and/or sedation is not, and should be avoided.

"We urge researchers and [research ethics review boards] to collaborate in the ongoing effort to minimize the risk of harm and discomfort associated with pediatric MRI research," the authors said in a news release from the journal publisher.

Meanwhile, Joy Hirsch, a professor of functional neuroradiology, neuroscience and psychology at Columbia University Medical Center in New York City, and a director of the CU's Functional MRI Laboratory, expressed little surprise with the Canadian team's observations.

"The FDA has characterized MRI as a minimal risk procedure," she noted. "And this is not something that involves radiation. So, this is not an invasive procedure and there is no incremental risk over time."

"But these are incredibly important questions that are being looked at," Hirsch added. "So you do want to have a clear risk-benefit analysis, and you do want to be careful. So, I would say that if the data suggests that contrast dyes and sedation -- both of which are foreign injects into the body -- are a problem, then we have to listen to the data."

More information

For more on MRIs, visit the American College of Radiology.