Dec 20, 2018

New imaging technology could lessen brain surgery risks

Photo of a brain surgery using the imaging needle from this study.

The "smart needle" in use during neurosurgery. Photo: Sir Charles Gairdner Hospital, Australia

Researchers have developed a hair-thin needle with a tiny camera and a warning system to more safely navigate during brain surgery, according to a feasibility study published in Science Advances Wednesday.

Why it matters: Current use of MRI imaging to assist with brain needle surgeries does not have the resolution to detect small blood vessels, making the risk higher that the neurosurgeon could cause a brain bleed when conducting a biopsy. This new needle — tested successfully so far on 11 patients — shows up to 98% accuracy in detecting those blood vessels. Brain bleeds can cause complications, which can be fatal.

How it works: Study author Robert McLaughlin tells Axios that the team developed the probe, which consists of an optical fiber that's roughly the thickness of a human hair, with a tiny lens fabricated at the end. It's integrated into the biopsy needle, which is just 2 millimeters in diameter.

  • The probe shines a light down the fiber and reflects images from the tissue and flowing blood via a technique called optical coherence tomography, often used for high-resolution medical imaging.
  • The team developed a smart image processing algorithm to automatically detect blood vessels as small as 110 micrometers (μm) near the needle.
  • As the needle is inserted, it shows the image on a computer screen, which will highlight in red when it senses a blood vessel near the needle.
  • "In practice, if there is a blood vessel there, then the neurosurgeon can simply rotate the needle (and the hole) or move forward a little," says McLaughlin, who's the chair of biophotonics at the University of Adelaide's Center for Nanoscale Biophotonics.

The results: They tested the "smart needle" in 11 surgeries, which had no complications resulting from their probe, McLaughlin says.

  • The needle detected blood vessels with a sensitivity of 91.3% and a specificity of 97.7% in blood vessels wider than 500 μm.
  • It achieved the same detections with a sensitivity of 86.2% and a specificity of 86.4% in all blood vessels, including those at the minimum diameter of 110 μm.
  • The team also tested the device’s deep vessel detection capabilities in 3 patients with deep tumors from glioblastoma, an often deadly form of brain cancer.
  • McLaughlin says they believe it could be used for deep brain stimulation for disorders such as Parkinson's disease.

Outside perspective: Brian Wilson, head of a research lab at the University of Toronto and the Princess Margaret Cancer Center who was not involved in the new study, tells Axios that "these values for sensitivity and specificity are excellent and would certainly be sufficient to justify deploying the technology in the clinic."

"It would make procedures such as deep-brain stimulation and brain tumor biopsy less risky for the patient. For example, in obtaining tissue in the brain to confirm, diagnose and stage tumors (which is important so that the best treatment can be given), there is a real risk of cutting a significant blood vessel, causing complications and sometimes even being fatal."
— Brian Wilson

What's next: The researchers hope to undertake a larger trial with patients who undergo brain biopsies, and are looking for a medical device manufacturer to help bring it to market.

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