Laser-based technology could make brain tumor surgery more accurate by allowing surgeons to better identify cancer tissue from normal brain tissue at a microscopic level during surgery. This could allow them to avoid leaving behind cells that could spawn a new tumor, say a team of researchers at the University of Michigan Medical School, Ann Arbor, and Harvard University, Cambridge, MA.

The technique allows them to “see” the tiniest areas of tumor cells in brain tissue, they say. The team is working to develop the approach, called stimulated Raman scattering (SRS) microscopy, for use during an operation to guide them in removing tissue, and test it in a clinical trial at U-M. Raman scattering involves allows researchers to measure the unique chemical signature of materials.

Using the SRS technique, they can detect a weak light signal emitted by a material after it is hit with light from a non-invasive laser. By carefully analyzing the spectrum of colors in the light signal, the researchers can determine the chemical makeup of the sample. By amplifying the Raman signal by more than 10,000 times, the researchers say that it is now possible to make multicolor SRS images of living tissue or other materials, and can make 30 images every second, which is the rate needed to create videos of the tissue in real time.

A multidisciplinary team of chemists, neurosurgeons, pathologists, and others worked to develop and test the tool. Their research is the first time SRS microscopy has been used in a living organism to see the “margin” of a tumor.

The current SRS microscopy system is not yet small or stable enough to use in an operating room, so the team is collaborating with a start-up company called Invenio Imaging Inc., which is developing a laser to perform SRS through inexpensive fiber-optic components. The team is also working with AdvancedMEMS Inc. to reduce the size of the probe that makes the images possible. A validation study, to examine tissue removed from consenting U-M brain tumor patients, may begin as soon as next year.

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