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Imaging advances reveal cellular details

Last month the medical school installed a new MRI magnet.

BY MITZI BAKER

In the last year, new imaging techniques have allowed scientists to track in ever greater detail cellular and genetic processes in animals and humans.

Christopher Contag, PhD, assistant professor of pediatrics and of microbiology and immunology, developed an imaging tool called in vivo bioluminescent imaging, which uses a glowing green cellular beacon to indicate when a gene is turned on or off inside living animals, even deep inside tissues. With this method, he and colleagues tracked Listeria infection in live mice and announced in March that they had found these bacteria, which can cause lethal food poisoning, hiding in the gall bladder. The ability to visualize the whole animal enabled the scientists to identify the gall bladder as an important bacterial bunker—something they wouldn’t have discovered without being able to image the entire body.

Dean Felsher, MD, PhD, assistant professor of medicine (oncology) and of pathology, used Contag’s technique to find evidence in mice that a gene known as Myc could determine whether a cell was cancerous. The findings, published in October, suggest that cancer cells in the mice livers may return to normal when the Myc gene is turned off.

Radiology professor Sanjiv Sam Gambhir, MD, PhD, director of the Molecular Imaging Program, is developing another technique that relies on what he calls “molecular detectives” to seek and spy on physiological processes in the body. These injected molecules can send signals from deep within the body that can be detected from outside by, for example, positron emission tomography. Depending on the type of detective, or imaging probe, used, the probes can detect cancer, cardiovascular and neurological diseases.

At the same time, scientists are developing larger magnetic resonance imaging machines to let doctors see more minute detail. The Center for Advanced Magnetic Resonance Technology, for instance, received a huge new magnet last month that will allow a twofold increase in resolution over current capabilities.