Cbyon takes image-guided surgery to new level

April 25, 2001

A new type of surgical system that provides views unlike any other image guidance product is being unveiled this week at the annual meeting of the American Association of Neurological Surgeons in Toronto, Ontario. The FDA-cleared product, called Cbyon

A new type of surgical system that provides views unlike any other image guidance product is being unveiled this week at the annual meeting of the American Association of Neurological Surgeons in Toronto, Ontario. The FDA-cleared product, called Cbyon (pronounced “see-be-yon[d]”) Suite, morphs MRI and CT data into a 3-D model that can be viewed not only in the traditional slices or 3-D configuration, but optically, as though the virtual tissue were being penetrated by an endoscope.

The practical benefits are remarkable. In advanced neurosurgery, miniature endoscopes built into the ends of surgical probes capture the area of the incision. While these scopes provide a view not otherwise possible, they are limited to the space immediately in front of the probe. When their optical data are fed into Cbyon Suite, however, a parallel universe of visualization appears. A virtual endoscopic image of the 3-D model can be projected next to the real one and manipulated to show different points in space: virtual tissue up to several millimeters beyond the tip of the probe, for example. With this enhanced viewing capability, surgeons can see and steer around vital tissues, such as motor strips or vasculature. They can also differentiate healthy from diseased tissue and, consequently, better judge the depth of tumor margins.

Based on the constant flow of optical data from the surgical probe endoscope, the computer automatically and continuously adjusts Cbyon’s 3-D model. The model can take into account brain shift, for example, which often happens when a tumor is excised. In this way, the surgeon is assured that the actual tissues are indeed where they appear to be in relation to the probe.

Providing context for interpretations by the surgeon is a 3-D macro view of a virtual surgical probe in its virtual surroundings. Surgeons can selectively tune out or subtract various layers of tissues or structures and highlight different tissue types.

Nothing is left to chance, according to Anita Chambers, director of marketing at the Palo Alto, CA, start-up. Cbyon Suite uses 100% of the CT or MRI data to create a “virtual patient,” an outwardly photorealistic image complete with skin, eyes, nose, and ears.

“We can basically do anything with that patient,” Chambers said. “We can highlight, emphasize, and de-emphasize any type of structure - remove the skin to see just the muscles; remove the muscles to see just the bony structure; remove the bony structure to see the brain; remove the brain to see only the vasculature.”

The system is designed primarily to assist surgical procedures in the brain, ear, nose, and throat. But the future may bring other opportunities. A miniature ultrasound transducer has been developed to provide real-time feedback for interventions in other parts of the body. The transducer, about the size of a pencil, would allow the computer to update the 3-D model in real-time. Surgical procedures on just about any part of the body might be accomplished; cardiac intervention is a prime candidate.

“When we get into anything in the abdomen or heart - any structure that is moving very rapidly, due to either breathing or beating - that’s when we need ultrasound,” Chambers said.

Cbyon was spun off from Stanford University two years ago. The company’s cofounder, Rahmin Shahidi, Ph.D., is director of the Image Guidance Laboratory in Stanford’s department of neurosurgery. Stanford, which licensed the technology to Cbyon, continues to feed ideas to the company. Shahidi and a half-dozen Stanford colleagues are developing advanced ideas that might be built into future versions of Cbyon Suite. An R&D team at the company works on near-term objectives, such as the integration of ultrasound.

Cbyon Suite incorporates proprietary software that allows 3-D perspective volume rendering, which produces essentially a 3-D “working model” of the patient’s anatomy. Dynamic data filtering allows the surgeon to customize the view of the anatomy to specific needs or preferences, selectively emphasizing, de-emphasizing, and removing tissues or structures to see those underlying or beyond them. This allows surgeons to visualize structures that must be targeted or avoided during surgery.

Virtual endoscopy provides a “tool’s-eye view” of the surgical probe penetrating the patient’s anatomy, a capability useful not only as a guide during surgery but as a means for presurgical practice. The location of the endoscope in 3-D space is determined through the use of tracking sensors built into the probe. With dynamic image synchronization, images obtained during the procedure using optical endoscopy are presented side by side with virtual endoscopy images, giving the surgeon the benefits of dynamic data filtering in the context of optical visualization. The virtual model of the patient is self-calibrating.

“The virtual endoscopy image is updated automatically to match the real endoscopy image,” Chambers said.

A powerful adjunct is virtual fluoroscopy, which benefits the patient and staff by reducing the radiation burden. Data from a preoperative CT scan is morphed into a fluoroscopic simulation that can be used during the procedure. A C-arm fluoroscope needs to be turned on only sporadically throughout the procedure to update the virtual model, an especially useful feature during spinal surgeries such as diskectomy, vertebroplasty, vertebral fusion, and pedicle screw placement, which require extended periods of visualization.

The technology behind these advanced capabilities has been in development at Stanford for about seven years. The effort to sell the product has only just begun. Chambers is putting together an in-house sales force to cover the U.S. but will rely on established distribution channels to address foreign markets. The neurosurgery meeting (April 21-26) marks the official unveiling.

The sales staff will have plenty to talk about. Cbyon Suite has been making the rounds of the country’s leading neurosurgical ORs. Units are installed at the Cleveland Clinic, Barrow Neurological Institute, UCLA, University of Utah, and Massachusetts General Hospital.

These and other sites have laid the groundwork for the commercial launch of Cbyon Suite as a therapeutic aid as well as a diagnostic one. In an early demonstration of how the product might improve complex neurosurgery, Cbyon Suite was used in the presurgical assessment of a patient, only to demonstrate that surgery would have been too risky. Since then, Chambers and her colleagues at Cbyon have decided that the Suite should include a diagnostic workstation.

“We offer a whole new way of visualizing data,” she said. “The customers could be radiologists, cardiologists - anyone in the diagnostic arena.”