US researchers said Wednesday they have developed a laser-based technology that may allow surgeons to quickly and accurately identify and remove brain tumors.

Researchers from the University of Michigan and the Harvard University described in the journal Science Translational Medicine about how they used this technique to "see" the tiniest areas of tumor cells in brain tissue, and to distinguish tumor from healthy tissue in the brains of living mice and humans.

"Though brain tumor surgery has advanced in many ways, survival for many patients is still poor, in part because surgeons can't be sure that they've removed all tumor tissue before the operation is over," said co-author Daniel Orringer, a lecturer in the University of Michigan Department of Neurosurgery.

Called stimulated Raman scattering (SRS) microscopy, the new technology works by shining non-invasive lasers into tissue and detecting the weak signal that emerges. By analyzing the signal's spectrum, the researchers can build images of the cellular makeup of the tissue.

By amplifying those signals, they were able to transform a technique that once took hours or days into one that works in real- time, and could offer a critical insight to surgeons in the operating room.

Since brain tissue and tumors contain different chemical makeups, the researchers can create images that precisely show where tumor "margin," the boundary area where tumor cells infiltrate among normal cells, is located, helping to guide surgeons in the operating room.

"A very experienced surgeon may be able to discern between brain tissue and a tumor based on subtle color differences," lead author Sunney Xie of the Department of Chemistry and Chemical Biology at the Harvard University said. "But many surgeons, I believe, will find this technology a useful guide."

The researchers applied the SRS microscopy to live mice during brain surgery, and demonstrated that it could image tumors in regions of living brains, regions where tissue appeared normal to the naked eye.

They then showed that the same was possible in tissue removed from a patient with glioblastoma multiforme, one of the most deadly brain tumors. Glioblastoma multiforme is very difficult to completely remove and on average patients diagnosed with the disease live only 18 months after diagnosis.

According to the researchers, the SRS microscopy may be as accurate as Hematoxylin and eosin staining, the current approach used in brain tumor diagnosis.

"For more than 100 years, Hematoxylin and eosin stain has been the gold standard for this type of imaging," Xie said. "But with this technology, we don't need to freeze the tissue, we don't need to stain tissue, and we don't need to biopsy -- this acts like an optical biopsy, and allows us to identify the tumor margins at a cellular level."

The researchers said they are currently working on building a handheld probe about the size of a toothbrush based on the SRS imaging that surgeons could use in the near future to analyze brain tissue during surgery without having to remove tissue.