This illustration shows how carbon nanotubes, once injected into the subject, can be fluoresced using near-infrared light in order to visualize the brain vasculature and track cerebral blood flow. (Courtesy Dai Lab)
The brain is a difficult organ to study, being both fragile and protected from easy access by the hard shell of the skull. Magnetic resonance has given us a tool to peer into the functionality of the brain, but its low resolution doesn’t give us much detail at the cellular level. A new technique developed by Stanford chemists now allows for non-invasive high resolution imaging of the outside layer of a mouse brain.
As reported in Nature Photonics, the technique involves injecting carbon nanotubes into live animals and then shining a near-infrared light through the skull. The nanotubes moving through the brain fluoresce between 1,300 and 1,400 nanometers when energized by the light, and the returning signal is picked up by a detector and reconstructed into an image. The scientists were able to visualize the brain down to three millimeters below the scalp at a resolution that allowed them to see active capillaries only a few microns in diameter. There’s still a long way before this technique can be used in clinical practice, since the human brain is much thicker and carbon nanotubes have not been ruled safe for human use by the regulatory authorities. Nevertheless, a great deal about neurological disease can be learned from studying animal brains, and we hope the new imaging method will help with those efforts.
Study in Nature Photonics: Through-skull fluorescence imaging of the brain in a new near-infrared window…
Press release: Stanford scientists use lasers and carbon nanotubes to look inside living brains…