Multimodal optical spectroscopy probe detects multiple types of cancer cells

July 7, 2017

In intraoperative testing, the multimodal optical spectroscopy probe detected cancer cells infallibly, with nearly 100% sensitivity.

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In 2015, a team of scientists at Polytechnique Montréal, the University of Montreal Hospital Research Center (CRCHUM), the Montreal Neurological Institute and Hospital, McGill University, and the McGill University Health Centre (MUHC; all in Montreal, QC, Canada) developed a handheld Raman spectroscopy probe that allows surgeons to accurately detect virtually all brain cancer cells in real time during surgery.

The research team has now perfected the invention and designed a new device with improved accuracy, sensitivity, and specificity that is capable of detecting not only brain cancer cells, but colon, lung, and skin cancer cells as well. In intraoperative testing, the multimodal optical spectroscopy probe detected cancer cells infallibly, with nearly 100% sensitivity.

"Minimizing, or completely eliminating, the number of cancer cells during surgery is a critical part of cancer treatment, yet detecting cancer cells during surgery is challenging," explains Kevin Petrecca, Chief of Neurosurgery, a brain cancer researcher, and holder of the William Feindel Chair in Neuro-Oncology at the Montreal Neurological Institute and Hospital. "Often, it is impossible to visually distinguish cancer from normal brain, so invasive brain cancer cells frequently remain after surgery, leading to cancer recurrence and a worse prognosis. Surgically minimizing the number of cancer cells improves patient outcomes."

The intraoperative probe developed in the laboratories uses the same Raman spectroscopy technology as the researchers' first-generation probe to interpret the chemical composition of the tissue examined. The new version is multimodal, also using intrinsic fluorescence spectroscopy to interpret the metabolic composition of the cells, as well as diffuse reflectance spectroscopy to analyze intrinsic tissue absorption in patients.

During recent testing on 15 brain surgery patients, sequential use of these high-sensitivity spectroscopy techniques—integrated into a single sensor coupled with a detection system, in combination with stimulating lasers, a highly sensitive camera, and a spectrometer—the surgeon benefited from molecular imaging that provided never-before-seen accuracy, with cancer detection sensitivity improved by about 10% compared with the first-generation probe.

Schematic depiction of the probe being used to interrogate brain tissue during surgery. The image shows a photograph of the probe held by a surgeon, Raman spectral associated with normal brain and cancer, as well as a magnetic resonance image (MRI) of a brain cancer patient with the red area representing the tumor.

The first-generation Raman spectroscopy probe is currently the subject of a randomized controlled trial involving patients with gliomas. The study will demonstrate the clinical benefits of intraoperative probe use during brain surgery. The results will be used to establish the protocol for an upcoming clinical trial of the second-generation multimodal probe.

In 2015, Petrecca and Frédéric Leblond, Professor of Engineering Physics at Polytechnique Montréal and a research fellow at CRCHUM, created a company, ODS Medical, to commercialize the probe. They have since initiated the formal approval process with the FDA to ensure transfer of the technology to hospital settings within a few years.

Full details of the work appear in the journal Cancer Research.