Editors' ChoiceNanotechnology

Window of Opportunity

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Science Translational Medicine  03 Sep 2014:
Vol. 6, Issue 252, pp. 252ec152
DOI: 10.1126/scitranslmed.3010264

Some of the most damaging brain diseases can be traced to irregular blood supply to the brain. Unfortunately, the usual imaging techniques used to study brain diseases, such as x-ray computed tomography and magnetic resonance angiography, have spatial resolution in the millimeters, and poor temporal resolution (minutes per image), so they are unable to see vascular structures in great detail or to monitor blood flow.

Now, Hong and colleagues describe a skull-penetrating fluorescence imaging technique that provides an unprecedented view of blood flowing through a living brain. In this new technique, the researchers injected water-soluble single-walled carbon nanotubes (SWCNTs) into the bloodstream of mice. After hair was shaved from selected areas of the head, the exposed areas were illuminated with a tissue-penetrating, near-infrared laser. SWCNTs inside the cerebral blood vessels fluoresced at wavelengths between 1300 and 1400 nm when energized by the laser, and this emitted signal was digitized into an image. Using this technology, the scientists were able to image brain areas as deep as 3 mm below the scalp and resolve active capillaries only a few micrometers in diameter. Importantly, this technique is fast (≤200 ms per frame), so it can track blood flow in real time.

There is still a long way to go before this imaging modality can be used in clinical practice, because the human skull is much thicker than mouse and carbon nanotubes have not been approved for use in humans. Nonetheless, this nanotechnology-based imaging approach has potential for providing new information on stroke, migraines, Alzheimer’s disease, and Parkinson’s disease, because blood supply could be monitored at a higher spatiotemporal resolution than achieved currently with standard clinical imaging modalities.

G. Hong et al., Through-skull fluorescence imaging of the brain in a new near-infrared window. Nat. Photon., published online 3 August 2014 (10.1038/nphoton.2014.166). [Full Text]

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