Chemists at Stanford University have developed a non-invasive technique using lasers and carbon nanotubes that visualizes blood flow in the brain, which could help provide powerful insights into strokes and possibly Alzheimer's disease. Current non-invasive technologies like CT scans or MRI visualize function at the whole-organ level but cannot visualize individual vessels or groups of neurons. The new technique, called near infrared-IIa imaging, or NIR-IIa, calls for injecting water-soluble carbon nanotubes into a live mouse's bloodstream. Then, the researchers shine a near-infrared laser over its skull.

The light causes the specially designed nanotubes to fluoresce at wavelengths of 1,300-1,400 nanometers; ideal for optimal penetration with very little light scattering. The fluorescing nanotubes allow scientists to view about three millimeters underneath the scalp and the image is fine enough to visualize blood coursing through single capillaries only a few microns across, they say. In addition, the technique does not appear to have any adverse affect on innate brain functions.

Although the technique was developed for use in mice, they say it could one day be applied to humans, potentially providing vital information to study stroke, migraines, and even Alzheimer's and Parkinson's diseases.