Even the state-of-the-art imaging equipment in today’s operating room does not make it much easier to distinguish tumor tissue from normal tissue in the brain during surgery. However, a new laser-based microscope technology, described in Science Translational Medicine (2015; doi:10.1126/scitranslmed.aab0195), may help surgeons see the difference between tumor tissue and normal brain tissue in real-time.

Called a stimulated Raman scattering (SRS) microscope, the device is now being tested at the University of Michigan (U-M) Health System in Ann Arbor. Researchers have used the SRS microscope to image more than 60 patient samples since June 2015, which was when the technology was first clinically tested.

“It allows the surgical decision-making process to become data driven instead of relying on the surgeon’s best guess,” said Daniel Orringer, MD, the U-M neurosurgeon piloting the technology in collaboration with the Pathology Department at the University of Michigan Medical School.

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Working with experts from several institutions, including Harvard University, where SRS microscopy was developed, the U-M team uses SRS microscopes to image brain tissue from neurosurgical patients.

“We’re able to visualize tumor that otherwise would be invisible to the surgeon in the operating room,” Orringer said.

If the current test goes well, the technology could be submitted to the FDA for approval within 2 years.

The team developing the SRS microscope hopes to create a product the approximate size of a microwave oven and more affordable than the imaging systems currently used, such as intraoperative MRI. Orringer believes removing the cost and space-capacity barriers will make the technology appealing to many surgeons.

“This technology has the potential to resolve a long-standing issue in cancer surgery, which is the need for faster and more effective methods to assess whether a tumor has been fully removed,” said Richard Conroy, PhD, director of the Division of Applied Science & Technology at the National Institute of Biomedical Imaging and Bioengineering at the National Institutes of Health, which provided funding for the development of the technology.

As Orringer and his colleagues continue testing the SRS microscope at U-M, they are building a second-generation system that can be easily operated during surgery.

The next version of the device would sit close to the operating table. Surgeons could readily insert a fresh tissue sample into the device, which would generate microscopic images on the spot. The entire medical team would be able to use and understand the device easily and the images produced would help determine immediately whether more surgery is required.

To get microscopic images today similar to what SRS produces, surgeons have to wait a half hour or more for tissue to be frozen, sectioned, stained, and interpreted by expert pathologists trained to spot the difference between cancer cells and normal brain tissue cells.

“The ability to determine tumor margins without having to send samples to a pathologist could increase patient safety and improve outcomes by shortening the length of surgeries and reducing the number of cases where cancer cells are left behind,” Conroy said.

“By optimizing surgical results, we’re ensuring that the patients will have the best possible outcomes after brain tumor surgery,” Orringer said.