This Is My Brain on 3-Tesla MRI
With functional MRI, scientists can measure brain activity as well as structure. Researchers place subjects in the center of a powerful magnet, then use different electromagnetic pulses to perturb the magnetic field. These pulses measure temporary changes in the blood’s hemoglobin concentration caused by neural activity, and MRI captures these changes with a series of snapshots of what’s going on inside the body. For instance, when Brewer scans my brain to see how it functions when I perform basic motor tasks, a protocol lasting about 6 minutes, he will take 5,520 different shots of the space between my ears.
The technology of MRI, which came into clinical use in the 1980s and has undergone constant refinement since, provides a non-invasive way of seeing what’s going on inside a person (or a rodent). As the magnets have grown more powerful, the images they capture have grown more resolute. At OMRF, with a magnet 140,000 times stronger than the earth’s magnetic field, Towner and his colleagues can examine cellular structure and activity at microscopic levels, without surgery or any tissue samples.
Scientists and physicians sometimes inject contrast agents—essentially dyes—to enhance visualization of certain structures. But, according to Towner, the evolving technology is decreasing the need for these compounds. He cites his own work as an example.
“There recently was a study of premature infants who were deficient in particular nutrients like zinc,” he says. Towner decided to dig deeper by using MRI to study the brains of young rats with similar nutritional deficiencies that, like their premature human counterparts, had spent time in an incubator in a 100-percent-oxygen environment. “We wanted to see if there were any neurological developmental changes caused by incubators and poor diet. And one way to do that is to use a contrast agent to see if there’s damage to the blood-brain barrier”, which separates brain tissue from blood vessels.
But through the use of certain biological markers already found in the brain, Towner devised a method of gauging neurological development in the rodents without contrast agents. “We can measure the animals’ neuronal development at a very early stage in a completely noninvasive way,” says Towner. The next step will be to adapt these protocols to people. “In humans, premature children with nutritional deficiencies often suffer from learning deficits. If we had a way to test at-risk infants using MRI, we could intervene much earlier with behavioral therapies to help stem the developmental problems they’ll face.”
Towner’s study has multiple clinical applications. First, it provides valuable pre-natal information about the importance of nutrients like zinc in pregnant mothers’ diets. His findings also caution against using pure oxygen on preemies. And, most importantly, they offer a way to identify and improve the lives of children facing substantial learning deficiencies.
“If you think of the technology as the starting point and human application as the end goal, researchers like Dr. Towner build bridges that connect the two,” says Brewer. “Clinicians need people like Dr. Towner.”
The W.M. Keck Building sits near a row of eucalyptus trees at the University of California, San Diego. A low-slung, boxy building, its austere facade is broken only by a riot of pink flowers and a small, glass pyramid that crowns it.
Brewer leads me into a laboratory suite, where I fill out a series of forms. I consent to participate in a research project that, according to the form, will involve “lying quietly inside the center of a large doughnut-shaped magnet for approximately 75 minutes.” The potential risks, the form instructs me, are manifold: claustrophobia, anxiety, dizziness, nausea and, worst of all, “the possibility of an abnormal finding.” I attest that I do not have a pacemaker, heart valve replacement, brain clips or dentures, am not pregnant, and do not have permanent eyeliner. Then I jettison all items containing any metal: Keys, change, cell phone, belt, money clip, shoes. Even my wedding ring.