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Coming to an Operating Theatre Near You: 7D Surgical Navigation

Starring a light-based system that uses surface imaging to map a patient’s anatomy for faster, more efficient surgery

The number seven

The global positioning system (GPS) is a network of satellites that orbits the earth twice daily, transmitting signal information to anyone on earth with a GPS receiver. When locked onto the signal of four or more satellites, the receiver computes the user’s location and time. Owned and operated by the U.S. government, GPS was originally developed for military purposes.

In September 1983, a Korean passenger jet on its way to Seoul from New York City was shot down after veering hundreds of miles off course into Russian airspace. All 269 people aboard the flight died. The incident led the Reagan administration to make GPS available for civilian use to avoid further tragedies owing to navigational errors. From there, the technology took off. Although many people associate GPS with route-finding devices used in cars, the technology is everywhere, including in cell phones, wristwatches, shipping crates and bank machines.

Dr. Victor Yang, an engineer, neurosurgeon and senior scientist in the Brain Sciences Research Program at Sunnybrook Research Institute (SRI), wants to provide surgeons in the operating room with the same kind of navigation offered by GPS. While working at his biophotonics and bioengineering lab at Ryerson University and completing his neurosurgery residency, he invented a surgical guidance system that improves the flow of work and provides doctors with a detailed, 3-D “map” of a patient’s anatomy before an incision is made. The map is used to guide them as they operate. Surgeons can use this tool to operate with greater efficiency than when using current navigation devices.

Yang and his research team, including Dr. Beau Standish, Dr. Adrian Mariampillai, Michael Leung and Dr. Peter Siegler, formed a company, 7D Surgical, to fabricate the system and commercialize the technology. Dr. David Cadotte contributed many after-work hours to the project and provided input to refine, optimize and test the system. The “7D” refers to the principle that an object in three-dimensional space has six degrees of motion: forward and backward; up and down; left and right; and rotations around each of these axes. The seventh dimension is time.

The technology, which is light-based, aims to minimize use of intraoperative X-rays. It is the first surgical guidance system to use surface or topographical imaging to “map” a patient’s anatomy.

Dr. Victor Yang illustration

Dr. Victor Yang drew many sketches in designing the surgical navigation system. Here, a schematic drawing of a patient on an operating table. Another diagram is seen in the opening image.

Drawing: Courtesy of Dr. Victor Yang

The system uses a structured light scanner and camera system to measure the three-dimensional shape (that is, the surface points, including curves) of the patient all at once. “Imagine you’re trying to measure the shape of a mountain. [With] existing technology, you’d send someone to a [particular] position of the hill and measure its location. You’d have to do this multiple times until you create the surface of the mountain. What we do is look at the entire mountain in one go,” says Yang, who is cross-appointed to Ryerson University and the University of Toronto.

The system projects a series of binary patterns (imagine the stripes of a barcode) onto the patient and records these images using cameras. The projection of the stripes is blended within the surgical lighting and is barely visible to clinicians. When the pattern is projected onto the patient, the system’s software analyzes deformations of the pattern and mathematically reconstructs the surface of the patient’s anatomy, creating a 3-D “map” of the anatomy. When combined with preoperative imaging data, this surface map can be used to guide surgeons as they work.

It’s not only novel, it’s also fast. The key to its speed is the way in which it matches preoperative imaging to the patient’s anatomy, a process called co-registration. With existing systems, surgeons match points on magnetic resonance imaging or computed tomography scans taken beforehand to points on the patient’s body, one by one. This process is slow and can introduce inaccuracies when there are slight differences between the two sets of points, says Yang.

In contrast, 7D Surgical’s software quickly matches the collected surface imaging data with preoperative imaging data. A tap on a foot pedal yields hundreds of co-registered points almost instantly.

Dr. Victor Yang

Dr. Victor Yang stands in front of the lighting hardware that is part of the surgical image-guidance technology he has commercialized and spun off into a company, 7D Surgical.

Photo: Curtis Lantinga

Manually picking dozens of matched points is laborious. Imagine losing those points and having to start over. “With existing systems, if you lose your tracking, it’s a big headache because now you have to reacquire [the points]; you need to ‘relock’ on. That process takes a long time. With 7D Surgical navigation, if you lose your tracking, it’s not a big deal because in less than a second you’re back on lock,” says Yang, who notes the system is 10 to 100 times faster than other guidance systems.

The technology also improves the flow of work by doing its job—providing fast navigation—without getting in the way. “A navigation system needs to function as if it’s not there. Any additional equipment that you bring into the operating room, depending on how intrusive it is, adds complexity and time,” says Yang.

Time saved in the operating room translates into savings for the health care system.

Unlike other navigation systems, 7D Surgical’s lighting and detection hardware maintains the surgeon’s line of sight. “Typically, tracking cameras are off to the side within the surgical operating theatre and the surgeon’s back can obstruct the line of sight of that tracking device. Our system has been developed to image from the top down, minimizing line-of-sight difficulties,” says Standish, the company’s chief executive officer.

Improved efficiency in the operating room spares frustration—and dollars. While costs vary according to the type of procedure, no surgery is cheap. Time saved in the operating room translates into savings for the health care system.

The technology will be adapted for diverse applications, says Yang. As a first step, it is tailored to spinal instrumentation procedures, during which a surgeon inserts implants such as pedicle screws and rods to stabilize the backbone and encourage bones to join after spinal fusion surgery. The team began with this application because it is an established market, says Standish. These procedures are performed for various conditions, including spinal fractures, herniated discs, spinal tumours and scoliosis. Moreover, research shows using guidance systems during these procedures improves outcomes.

“With an established foothold in the spinal fusion market, our product focus will be extended to neurosurgical procedures. The benefit of our technology is that the core hardware navigation can be used in multiple anatomical locations, where site-specific software packages will become add-ons to the system. This allows for a versatile navigation product that has clinical utility for multiple surgical procedures,” says Standish.

Yang and his team began working on the technology in 2009, during his surgical training. He was experiencing difficulties with existing guidance systems. He realized his colleagues were having similar troubles and recognized an opportunity.

Dr. Victor Yang tests surgical navigation system

Dr. Victor Yang (right), tests the surgical navigation system he invented on one of the first patients in a clinical feasibility study of the device at Sunnybrook.

Photo: Doug Nicholson

This is another element that separates 7D Surgical from other medical device startup companies: its approach. Rather than invent a technology and figure out where it can be used, 7D Surgical developed its product around a bona fide problem. “We know we have a fantastic application,” says Yang. “There’s a clinical demand for it. We know where all the difficulties are. One of our earliest meetings was to map the [surgical] workflow and technological requirements of that workflow to make a product. These designs address a clinical problem.”

Yang realized the technology was commercially viable once he learned he could use components from consumer electronics, such as computer projectors and cameras, in the system’s hardware. That these parts are widely used and fairly inexpensive means the company can keep manufacturing costs low.

The system has generated buzz among Yang’s clinical colleagues. Years ago, Dr. Todd Mainprize, who heads neurosurgery at Sunnybrook, heard of Yang’s technology and was so intrigued that he visited Yang’s lab at Ryerson for a peek. Even at that early stage of development what he saw impressed him. Since then, Yang has been recruited to SRI, and is using the device development lab in SRI’s Centre for Research in Image-Guided Therapeutics to assemble the system.

Mainprize has used the device in SRI’s preclinical operating room. He says it’s a big improvement over existing technologies. “I have not had much success with spinal 3-D navigation over the years. You spend an hour trying to set it up, and you end up abandoning it because it doesn’t work. Anatomically, you know where the screw goes, and the navigational unit is saying it should go two centimetres lower—right in the middle of the spinal cord. I’ve used [the 7D system]. It’s seamless, [takes] 10 seconds and has been accurate every time I have used it. It will be a big step forward,” he says. Yang, along with neurosurgeons and orthopedic spinal surgeons at Sunnybrook, is leading initial clinical feasibility studies of the device.

The goal is to have the system available for sale by 2016. While the price is to be determined, Standish says it will be comparable to existing products—in the range of $250,000 to $400,000.

The team at 7D Surgical is confident that users will find the technology intuitive and user-friendly. In addition to Mainprize, Dr. Ashish Kumar, a neurosurgeon from India, has used the system with ease. “With [other] surgical navigation systems, surgeons are invited for an entire weekend to learn how to use them. This gentleman, who hadn’t used our system before, was using it to its full capability within three minutes,” says Standish.

Noting SRI’s track record of commercializing research, Yang sees similarities between 7D Surgical and companies that were spun out of technologies invented by SRI researchers. “I think we’re following the same path—finding the clinical application first, having a good conceptual design, surveying a lot of technologies before settling on [something] manufacturable and commercializable, and then having a dedicated team to make the sacrifices to do it.”

Yang’s research is funded by Brain Canada, Canada Foundation for Innovation, Canadian Institutes of Health Research, Natural Sciences and Engineering Research Council of Canada and the Ontario Ministry of Research and Innovation. He holds the Canada Research Chair in Bioengineering and Biophotonics.

Dr. Victor Yang illustration
Dr. Victor Yang
Dr. Victor Yang tests surgical navigation system