Scientists and MDs have a wide range of technologies available for the imaging of live tissue, but each of these comes with its own limitations - be it poor contrast, low resolution, long response times or the viewing process damaging the tissue being observed. A team of Harvard researchers has developed a new type of optical biomedical imaging that promises to overcome these obstacles and is so fast and high-resolution that it can capture live video of cells and molecules.

The new technology is based on stimulated Raman scattering (SRS), a non-intrusive optical technique that detects the vibrations in the chemical bonds between atoms through absorption and subsequent emission of photons. By intelligently rearranging the photodetectors so they would capture more photons, the team used SRS microscopy to obtain streaming footage of blood cells squeezing through capillaries, proteins and lipids, and to track the migration of medications in skin.

"When we started this project 11 years ago, we never imagined we'd have an amazing result like this," commented X. Sunney Xie, who was part of the research team. "We're already looking forward with great anticipation to applications of SRS microscopy in hospitals. It's now clear that [it] will play an important role in the future of biological imaging and medical diagnostics."

Previous SRS microscopy captured only about one image per minute, far too slow to monitor live tissues effectively, but the team was able to speed the collection of data by more than three orders of magnitude, obtaining video-rate imaging.

Even with the state-of-the-art technology, surgeons must now have their patients wait on the operating table for about 20 minutes as they're waiting for the results of histological analysis. The improvements the Harvard team brought to SRS microscopy eliminate this inconvenience by providing real-time scanning, in an advance that could strongly benefit surgery to remove tumors and other lesions.

This technology could also do a great job in complimenting MRI, which has a depth of penetration better suited to imaging organs and other large objects deep within the body. Together with endoscopy, the technique can also be used to view three-dimensional sections of living tissue, layer by layer.

The research was funded by Boehringer Ingelheim Fonds, the Bill and Melinda Gates Foundation, and the National Institutes of Health. A paper describing the team's work is due to published this week on the journal Science.

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