5 minute read
Dalhousie biomedical engineers’ world-leading research
Cancer is the leading cause of death in Canada. There are 100 kinds, and none are the same. Not every cancer is a death sentence, however with early detection, research and breakthroughs in treatment, some cancers are closer to a chronic disease than a killer. Brain cancer is not one of those.
According to Canadian Institutes of Health Research, around 50,000 Canadians are currently living with brain cancer. There are aggressive treatments available like surgery and radiation, but the brain is unique for surgeons in that accessing and removing tumors is incredibly challenging without harming healthy tissue.
Dr. Jeremy Brown, P.Eng., and his research team at Dalhousie’s School of Biomedical Engineering have been working to solve the problems brain cancer surgeries pose. They have designed the world’s first high-resolution endoscopic surgical and imaging probe, giving surgeons the ability to see brain tumors at 10 times the resolution of an MRI or CT scan.
Neurosurgeons operate with mere millimeters of space between cancerous tissue and healthy tissue. Older probes are both too large and provide images that are too low in resolution. And, during surgery, as you begin removing tissue the MRI will be inaccurate since things move.
“The main thing we are using our probe for is to identify residual tumors in gliomas, which are very common,” Dr. Brown explains. “When residual tumors are missed, then the cancer comes back faster – If too much healthy tissue is removed then the quality of life is poor. Our probe helps with the accuracy of resection.”
Dr. Brown’s high-resolution endoscopic surgical and imaging probe solves both the probe size and low-resolution problem, which gives neurosurgeons the ability to gauge their progress as they work.
The probe is made from a piezoelectric crystal and is then mounted on a 3D printed bayonet-shaped base with circuit boards used to transfer the signals to the electronics through a cable. The piezo crystal is first given a thin layer of gold and then laser micro-machined into an array of about 100 sensors. Using microfabrication techniques, the sensors are packaged into a 3 mm footprint. Dalhousie University has licensed the intellectual property to a local spinout company, Daxsonics Ultrasound (of which Dr. Brown is a co-founder), and Daxsonics is commercializing the technology.
Beyond just faster surgeries, this advance in medical technology can save lives and result in better outcomes with fewer disabilities. The probe’s precise images allow surgeons to adapt surgical plans in real time as needed and reliably confirm all cancerous tissue has been removed while the patient is still in the operating room. The endoscopic and imaging probe was used successfully in the first two surgeries at the QEII Health Sciences Centre earlier this year.
“We build all our own devices and electronics,” says Dr. Brown. “We’re very good at miniaturizing ultrasound probes with extremely high resolution and neurosurgery was a perfect practical application for that. The probe can fit down a surgical pathway because it’s about the same size as all of the other surgical tools.”
“In the QEII’s first brain tumor surgery using our device, our very high-resolution ultrasound made it easy to differentiate cancerous tissue from healthy tissue. There’s a stark contrast between the two tissues. That’s helpful in guiding the tumour resection and minimizing damage to healthy tissue.”
The second surgery at the QEII closed off a brain aneurysm without blocking any downstream arteries.
“The probe visualizes blood flow extremely well. Surgeons can see where all the arteries are without having to dissect them, and this will allow them to confidently clip the aneurysm without blocking any downstream arterial branches.”
In addition to tackling a type of cancer that is nearly always fatal, Dr. Brown knew the high-resolution endoscopic surgical and imaging probe could help with spinal surgery. These surgeries require a probe with a different angle than brain surgeries and his team re-designed the probe, lab tested it, and have already used it in three spine surgeries.
Dr. Brown and his team are currently working on a promising secondary tool for the probe, which would give it the ability to vaporize cancerous tissue—turning it into gas bubbles with blasts of high-intensity sound waves instead of heat. This would allow surgical teams to image and treat tumors at the same time, providing more precision than radiation therapy and saving heathy tissue from damage.
While other ultrasound probes now exist, Dr. Brown’s is the smallest and combines the probe and the secondary therapeutic tool—a unique factor which allows for the dual purpose of high-resolution imaging and vaporizing cancerous tissue. He and his team are working with commercial partners to ensure this feat of bio-medical engineering has a broader impact than Nova Scotia.
“We’re doing world-leading research in Halifax, and we’re going to have a global impact,” says Dr. Brown.
