Mary Foley teaches people how to operate multimillion-dollar magnetic resonance imaging (MRI) machines at the Martinos Center for Biomedical Imaging in Boston.
How many tesla would you like?MRI machines use electromagnetic radiation to make cross-section images of soft tissues within the body, like the brain and spinal column. Powerful new machines known as fMRI machines (the "f" is for "functional") generate a stronger magnetic field, "so you can get more minute detail," Mary explains. The strength of the magnet used inside an fMRI is measured in tesla (after inventor Nikola Tesla), and the fMRIs used at the Martinos Center range from a one-and-a-half-tesla to a seven-tesla machine. "The rule of thumb is a million dollars a tesla," says Mary.
From brain structure to brain functionMary loves working at the Martinos Center because "we have great minds here that imagine the possibilities." One of those great minds figured out that the new, high-field magnets could generate a rapid succession of images that would reveal patterns of blood oxygenation in the brain while patients performed mental tasks. Since more oxygen flows to active regions, the result is a map of the areas used for particular cognitive tasks. "We do a 3-D structural image of the brain in the beginning, and then overlay information from the fMRI scanner," Mary explains.
The machines are being used for a wide range of investigations, such as a study on identical twins in which one twin suffers from post-traumatic stress syndrome. "You always have a control group to compare to your study group," says Mary. "The idea is to try and break down the brain pathways to understand why some brains work one way and others in another way." One important study asks Alzheimer's patients to commit a set of images to memory and then try to recall them once inside the machine. "You can see the circuitry activating in a person of similar age that fails to activate in the Alzheimer's patient in response to the same stimuli." Another study is being conducted on people who are addicted to cocaine, with the ultimate goal of creating a drug that will interact with the relevant brain circuits and break the addiction cycle.
No place for claustrophobicsUndergoing an fMRI means lying on a "bed" that slides into big magnetic tube; the patient is packed in so tightly that movement is impossible. The patient communicates via a two-way intercom or by squeezing a ball that sets off an alarm. The head sits inside a coil that operates like an antenna to increase the brain's electromagnetic signals. A camera at the end of the machine projects images into the tube so the patient can see and respond to them.
An fMRI can produce four images every second, and a scientist observes the time-lapse series of "slices" of the patient's brain on a separate screen. "The changes in oxygenation levels are very subtle, and the brain has to be scanned very quickly and repeatedly to catch changes in blood flow," says Mary. Each procedure on a single person takes two to three hours.
And leave the dangly earrings at homePatient screening is stringent, since the magnets will stop pacemakers and pull any metal parts out of the patient's body. "You have to come to work MRI-friendly," says Mary. "The machine will pull a cell phone off your hip. If your ID badge is on a metal clip, it'll fly into the machine and could kill the person inside." Mary shows scientists and their staffs how to operate the machines correctly and safely, and also helps establish their experimental protocols.
She grew up in South Boston and got a certificate in radiology, but hedged her career bets with a bachelor's degree in business management. Then, 25 years ago, Mary was hired by the radiology department at Massachusetts General Hospital, where she got to know the doctor who now heads the fMRI research department. She was fascinated by his descriptions of the sort of brain mapping he hoped to do in the future-and that's what the department is now doing. "What interested me about MRI is that the technology changes faster than you can keep up with," she comments happily. "So it was never going to be routine—certainly not here!"
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Name: Mary Foley
Born: South Boston, Massachusetts, 1959
Where I go to watch IMAX films: Usually the Boston Museum of Science
Job: Operation manager, Martinos Center for Biomedical Imaging, Massachusetts General Hospital
Education: Bachelor’s degree in business, Salem College; licensed radiographer in MRI imaging
Book/s I'd want if I were stranded on a desert island: Confederacy of Dunces, by John Kennedy Toole
Favorite place to visit: Ireland
Favorite food: Spicy Mexican
Favorite artist/kind of music: Jazz, Stan Getz
Biking experiences: I once rode my bike on a three-week trip around Ireland.