A new research advance in MRI (magnetic resonance imaging) technology can safely detect molecules called free radicals, which are associated with traumatic brain injury. The technology is a step toward transforming diagnostics by making these markers visible to clinicians for the first time.
Researchers have experimented for years with detecting free radicals with MRI, but earlier efforts took too much time and required too much radio frequency energy, which led to unacceptably high levels of tissue heating.
A new higher-speed, higher-efficiency method that avoids dangerous heating is described in this paper. The method was developed by physicist Matt Rosen, a researcher at the Massachusetts General Hospital/A.A. Martinos Center for Biomedical Imaging in Charlestown, Massachusetts.
So far, he has demonstrated it can detect free radicals in the brains of living rats injected with the highly reactive molecules. Because Rosen achieved the result using low-field MRI, which uses smaller magnets than classic trailer-sized MRI units, it could be used in future smaller, portable MRI systems.
After traumatic brain injury, free radicals—molecules formed during the initial injury—can damage healthy brain tissue through chemical and cellular processes that cause swelling and cell death. The swelling alone can cause further injury or even death.
Used in an emergency situation, the technology could confirm the severity of a head impact and prompt medics to administer antioxidant drugs to neutralize free radicals. The effects of any such drugs could then be observed through a second scan. It could even help doctors determine whether surgery would be advised to relieve brain swelling.
Because free radicals aren’t all bad—they also play a role in biological signaling in the brain—the technology could also enable researchers to measure what constitutes a normal mix of free radicals in the brain (or elsewhere in the body), and develop a baseline against which to detect dangerous levels.
Still, commercialization of free radical detection is likely years away. “Whether Matt will ultimately be able to visualize free radicals [produced by the body, as opposed to ones injected in rats] is of course still an open question, but I have a much greater level of optimism given his recent results,” says Bruce Rosen (no relation), a professor of radiology at Harvard Medical School and the director of the A.A. Martinos Center.
While the technology could have theoretical benefits for people with a range of diseases and conditions—including stroke, cancer, and dementia—that involve the release of free radicals, the implications for patients with brain injuries is significant. Traumatic brain injury is considered an epidemic in the United States; more than five million people live with disabilities resulting from brain injury.
Conventional MRI provides high-quality images of the structure of the brain and can detect bleeding or physical damage, but offers no window into the far more subtle release of free radicals. In the absence of such information, researchers are trying to use a variety of methods to detect damage on a smaller scale (see “Detecting Subtle Brain Injuries” and “Inexpensive Brain Scans Could Catch Concussions”).