Engineering Newsletter

Elizabeth Hillman | Biomedical Engineering

Walk into any clinical research lab and you will undoubtedly find one or more microscopes. The problem with conventional microscopes, however, is they can only show images of thin slices of dead tissue or cells in a dish. It takes a special kind of instrument to produce images from inside the living body, which is exactly the kind that Elizabeth Hillman is building.

“It is a significant technical challenge to build imaging systems capable of studying cellular or molecular processes in living organisms,” says Hillman, assistant professor of biomedical engineering and radiology. “You need devices that can image very fast and in 3D and that show you lots of different things at once. It’s a complex problem, one that forces you to think about physiology and physics at the same time.”

One of the primary areas of focus in Hillman’s lab is using optical imaging techniques such as microscopy to investigate the brain, particularly the relationship between blood flow and neuronal activity. Functional magnetic resonance imaging (fMRI), one of the most ubiquitous tools used to investigate neuronal activity, relies on detecting subtle changes in blood flow in the brain. “The problem is, we really don’t understand why these changes in blood flow occur,” says Hillman. “Even the best neuroscience textbooks only devote a page or so to blood flow in the brain.”

Hillman’s work is beginning to tease out this complex process, improving our fundamental understanding of how the brain functions, and also raising the possibility that fMRIs will one day prove even more useful and revealing. In another project, she is developing a technique that permits her to create images of the organs in live lab mice, which she hopes will allow pharmaceutical companies and researchers to study diseases and treatments without sacrificing large numbers of animals. She has also developed techniques to make images of living human skin, resulting in an imaging system that shows promise as a way to minimize excision while removing skin cancers from the face, and she is using optical imaging to investigate how the electrical activity in cardiac tissue changes during a heart attack.

Because all of these measure different wavelengths of light, none require the heavy shielding or careful dose monitoring necessary in radiologic imaging. Moreover, almost all take advantage of existing contrast agents, such as blood, which changes color as its oxygenation level changes, or green fluorescent protein (GFP), which can be modified to label specific types of cells. Hillman hopes that ultimately many of her imaging tools will prove useful in the clinic and as laboratory research tools, where they can be used to improve fundamental understanding of both physiology and disease. She is quick to point out, however, that although optical methods are extremely well suited to clinical application, she does not expect her techniques to entirely replace MRIs. “Optical imaging isn’t going to be the next MRI,” she says. “MRIs do some things well, but they can’t tell you things like how bad the burn on your arm is or whether you have good blood flow in the back of your eye. Our systems can.”

Hillman, who received her PhD from University College, London, did postdoctoral research at Massachusetts General Hospital’s Center for Biomedical Imaging before coming to Columbia.