Brain Bleeds Begone

Jonathan James
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A new optical tool shines a light on hidden blood vessels, helping surgeons reduce the risks of neurosurgery.

The complexity of neurosurgery has long been used as an amusing idiom to highlight simpler endeavors: “Well, it’s not exactly brain surgery, is it?” But it really is no laughing matter. A single slip from a needle can have catastrophic consequences for patients.

Today, MRI scans are used to identify major blood vessels preoperatively but, during surgery, the risk is left in the skilled hands of the neurosurgeon. The rupture of even small blood vessels can be extremely damaging: 2 percent of brain surgery patients are left disabled as a result of bleeds caused by needles. One percent will die. (1)

Medical engineers have been puzzling over how to address the problem. “It quickly became obvious that a needle that could see where it was going had huge potential in an area as delicate as the brain,” says Professor Robert McLaughlin of the University of Adelaide, Australia. He’s one of the lead authors of paper in Science Advances (2), which describes a new imaging needle able to detect vessels as small as a tenth of a millimeter in diameter. “Our imaging needle gives a detailed view of what is immediately adjacent to the needle tip,” explains McLaughlin. “It provides the neurosurgeon with a real-time view of at-risk vessels.”The setup is simple. A razor thin optical fiber with a tiny lens is fabricated into the end of the needle, allowing the surgeon to shine light onto the brain tissue. The resulting light scatter is then detected by a camera. Using optical coherence tomography (OCT), the team were able to develop an image processing algorithm that could automatically detect blood vessels. “Flowing blood has a characteristic appearance in these images,” explains McLaughlin. “When the needle is next to a blood vessel, the computer highlights it, allowing the surgeon to see it in real time.”

To validate the tool, the team tested the needle in 11 patients undergoing brain surgery. The first step was to scan the surface of the brains of patients undergoing craniotomies to check if the needle could detect the visible surface vessels. Then, for three patients, the researchers went a step further by drilling a hole into the patient’s skulls. By inserting the needle into this hole, they attempted to detect where blood vessels were located and compared this with MRI scans.

The results are promising, and so McLaughlin wants to take the project further, firstly with larger trials in neurosurgery, but also beyond: “We are now developing the next generation of imaging needle that can also detect cancerous tissue.”

Brain Bleeds Begone

Surgeons test the efficacy of the new brain imaging needle (reproduced with permission from the Centre for Nanoscale Biophotonics, University of Adelaide)