A multi-institutional consortium that includes Duke has created startlingly crisp 3-D microscopic views of tiny mouse brains—unveiled layer by layer—by extending the capabilities of conventional magnetic resonance imaging. By studying the mouse brains, researchers hope to gain insights into the relationship between genes and brain structure in humans.
"These images can be more than 100,000 times higher resolution than a clinical MRI scan," says G. Allan Johnson Ph.D. '74, Charles E. Putman Distinguished Professor of radiology and professor of biomedical engineering and physics. He is lead author of a report describing the innovations in the research journal NeuroImage.
Images on the website for Duke's Center for In Vivo Microscopy, which Johnson directs, reveal examples of these innovations in action. In one video, two different mouse brains—one from a normal animal and the other from an animal missing a gene linked to normal mental functioning—assemble themselves before the viewer's eyes, structure by structure, through a series of time-lapse photos. Once complete, the side-by-side images revolve as overlying tissues dissolve into a computer-rendered transparency. What remains visible are two color-coded brain structures—the ventricles and hippocampus—showing specific genetic differences.
Such high-resolution magnetic resonance imaging provides distortion-free 3-D images that make it possible for scientists to distinguish subtle tissue differences in the brain, Johnson says. "The specimen is still actually in the skull. It hasn't been cut by a knife. It has not been dehydrated and distorted as it would be in conventional histological techniques."