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Laser probe lets brain surgeons identify cancer cells with sound

Neurosurgeons may listen while they work in future

Dr P. Marazzi/Science Photo Library

It takes steady hands and experienced eyes to remove brain tumours. Soon, sharp ears could also be crucial, with surgeons being guided by sound as to whether they are slicing through cancerous or healthy cells.

In recent brain operations, surgeons used a laser probe to help determine where brain tumours began and ended. In these, a signal showing whether cells were healthy or cancerous was displayed visually on a screen.

Now, this signal has been adapted into an audio one with the goal of allowing surgeons to listen for cancer as they operate and instead focus their visual attention on where they are cutting. The development could lead to faster, safer and more successful brain surgery.

“We’ve shown how to give accurate guidance to surgeons in a way that allows them to keep their focus on their scalpel,” says Matthew Baker at the University of Strathclyde in the UK.

The new audio signalling software has yet to be tested in a clinical setting but could prove a useful surgical tool, says Adam Waldman at the University of Edinburgh, UK.

Cell fingerprints

The software works with handheld probes that distinguish between healthy and cancerous cells using Raman spectroscopy. This technique involves firing lasers at the cells and analysing how the light bounces back. The results produce a graph that acts a bit like a fingerprint for the cells.

By looking at the graph’s shape, it is possible to tell if the probe is hovering over a cancerous cell or a healthy one. This helps surgeons remove as much of a tumour as possible but avoid non-cancerous cells. Failing to remove tumour cells could leave the patient with the cancer, while removing healthy tissue could cause brain damage.

The probe technology has been successfully trialled in Canada and the UK since 2015. Baker and his team hope their audio signalling software will further improve the method.

The new software, developed through a collaboration between several UK universities and hospitals, takes the most important features from the probe’s signal and synthesises them into sounds instead of a visual representation.

Change of tone

“Looking back and forth between a screen and the patient is not ideal. It would be better if a surgeon’s focus could be in one place,” says Baker. The resulting tones are distinct enough to reveal the differences between the cells. Using only their ears, participants in a first study using the technology were able to distinguish between healthy and cancerous cells with an accuracy of over 70 per cent.

This is below the 90 per cent accuracy that can be achieved by looking at the visual outputs, but Baker is confident it will be improved upon. The two methods have yet to be compared during surgery, where the different types of multitasking required will affect the results.

“The probes can provide the information needed to accurately identify cancerous tissue. We’re working out the best way to give that information to surgeons,” says Baker.

Journal reference: Analyst, DOI: 10.1039/C6AN01583B

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