IN THE NOSE Developing technology lets surgeons follow their preferred surgical track through delicate sinus anatomy.

Think back to this morning's commute. You knew where you were headed and the best route to take, but perhaps you still relied on your Waze app to help you avoid traffic snarls and speed traps along the way. Surgeons, even experienced ones, enjoy the same reassurance when they lean on image-guided software as they drive their probes through the twists and turns of the sinus cavity. Watching exactly where their instruments are located as they operate mere millimeters from delicate structures gives them the confidence they need to perform safer and more complete surgery.

"Seeing how far you're operating from the orbit and skull base provides a little more confidence that you won't blow through a sinus wall," says Gopi Bipin Shah, MD, an ENT-otolaryngologist at Children's Health in Dallas, Texas.

Is image guidance needed for every procedure? No, says, Dr. Shah, but it's especially helpful during revision surgery — "because anatomical landmarks have changed slightly," she says — and for complicated cases, such as the removal of polyps and sinonasal tumors.

"Navigation will let surgeons move beyond our current limits to help treat more advanced disease," says Dr. Shah.

As the technology continues to develop, here are some of the latest advancements you and your surgeons need to know about.

1. Streamlined performance
Brent Senior, MD, FACS, FARS, chief of the division of rhinology, allergy and endoscopic skull base surgery at the University of North Carolina at Chapel Hill, says the makers of image guidance platforms are designing newer systems for the clinic setting to address the increased demand for in-office use of the technology during balloon sinus surgery.

The stripped-down units, which don't feature the bells and whistles of more advanced and expensive platforms, are available at a lower cost, which is also attractive to surgery centers operating on a tight budget. The units' electromagnetic systems track a single instrument, probe or balloon dilation device, says Dr. Senior. They also boast a thin profile and small footprint, making them ideally suited for settings with limited clinical space.

"Most of the units ENT surgeons use in the OR contain targeting software capabilities that let you use the platforms during complex neurologic procedures," says Dr. Senior, who points out the new streamlined image guidance platforms don't have advanced software, meaning they're designed for use during relatively basic sinus procedures.

TIGHT SPACES Newer image-guidance units are designed specifically for facilities with limited floor space in patient care areas.

2. Improved navigation
Image-guided technology makes surgical techniques easier to apply. New image-guidance systems that are beginning to receive FDA approval give surgeons the ability to plot out a track into an individual patient's sinus, says Dr. Senior. The tracking software provides real-time feedback by alerting surgeons if they stray from the intended path, which is superimposed over their endoscopic view.

"That capability lets surgeons map out the ideal intraoperative plan and preload it into the system," he explains. "During surgery, the surgeon can follow the track as he enters the sinus and watch as he moves along his preferred approach."

Dr. Senior believes the developing technology will likely provide the greatest benefit in frontal sinus surgery. "That's the area with the most complex anatomy, and the real-time tracking will let surgeons draw out their operative course around existing anatomy to minimize manipulation of the sinuses as they move to the target area," he adds.

Dr. Shah enjoys being able to reference an MRI-CT fusion image during an advanced tumor case or a skull base procedure, such as transsphenoidal surgery. She says the combined images provide valuable information about bone anatomy, soft tissue landmarks and the tumor she's targeting.

GOOD LOOK Surgeons and patients are seeking out facilities that boast image-guidance technology.

3. Better instrumentation
The 2 main ways instruments communicate with image-guidance platforms have remained consistent:

Electromagnetic guidance. Surgeons don't need to maintain a direct line of sight between instruments and the image processor. They typically must use proprietary instruments, however, and the surgical team must keep metal items away from the patient in order to avoid interfering with the system's electromagnetic field.

The tips of proprietary suction devices, which are used frequently, can bend slightly over time, making navigation more difficult, according to Dr. Shah. She says the manufacturers of image-guided technology are responding to that concern and producing hardier instruments. She also points out that some systems have developed disposable suction devices, so the wear and tear on the instruments doesn't impact how well they perform in practice.

Infrared guidance. Passive infrared systems have fiducial markers placed on the patient and instruments that reflect infrared light back to the system camera. Active systems have infrared emitting diodes on operating instruments that are actively tracked by an overhanging camera. With both types of technology, you must maintain a clear line of sight between instruments and the imaging unit. These systems are highly accurate and especially helpful and convenient during routine sinus cases, because the small markers placed on the distal ends of individual instruments easily track their locations during dissection. Passive systems do not require wiring of instruments to the machine, giving surgeons freedom of movement in the surgical cavity.

Single-use, proprietary instruments used with electromagnetic units add to case costs, which can be a detriment, says Dr. Senior. He adds, "Some companies are starting to develop adaptors that would let surgeons use their own instruments with electromagnetic systems, although the adaptors still require the purchase of disposable wiring to connect conventional instrumentation to the system, and the wires can be expensive.

"From my seat, it appears that electromagnetic systems are gaining in popularity, although both modalities perform equally well in terms of efficacy and accuracy."

Maintaining the peak performance of a navigation system and its instruments or sensors depends on downloading regular, and pricey, software upgrades, warns Dr. Shah. "As technology advances, it definitely gets cooler and cooler," she adds. "But then it's sometimes difficult to balance it with the additional cost."

4. Ease of set up
Photo registration software is a slick new technology that's recently received FDA approval, according to Dr. Senior. "You're able to take a picture of the patient's face and input it into the image-guided system, which registers itself to the photograph," he explains. "The technology uses face recognition software to correlate the patient's CT scan to the surface anatomy captured in the picture in order to register the patient's anatomy to the navigation unit."

Dr. Senior says the automated process replaces the need to place fiducial markers on the patient's face and manually register anatomical landmarks. "That development should improve the speed and ease with which units are configured and set up between cases," he adds.

Metal on the surgical field might interfere with the calibration of some systems, points out Dr. Shah, who voices frustration over sometimes having to clear the area of metal objects when setting up for a case.

Dr. Shah says it's important to work with a navigation system that catches the scan of the patient's anatomy faster, so there's less down time when setting up the unit for use. She has, over time, learned the tricks to calibrating the systems she uses as quickly as possible, but agrees that streamlining the process would be a significant improvement to the way she works.

Image-guided technology makes surgical techniques easier to apply.

5. Improved recoveries
Dr. Senior says surgeons like to pack nasal cavities with steroid-eluted stents, which are particularly helpful in polyp cases, because steroids help prevent polyp recurrence after they've been surgically removed, and promote healing within the cavity. The limitation of using the stents is that they're quite expensive — approximately $600 each, so you'd presumably need 2 per case — and therefore significantly increase case costs, according to Dr. Senior.

"The evidence is mounting that patients who receive the stents do very well after surgery, but questions remain about whether they do better than patients who receive oral steroids," says Dr. Senior. "One clear benefit, however, is that the stents reduce use of oral steroids and associated side effects that can have a particularly negative impact in opioid-sensitive patients. Stents provide patients with the benefits of post-op steroid therapy without risk of suffering any of the systemic side effects."

Coming soon
Intraoperative MRI and CT are increasing the ability to have real-time image-guidance technology, and robotics will offer significant possibilities in the future, according to Dr. Senior. Specifically, he thinks "image-guidance technology will create boundaries for dissection, and robots will work within those physical limits." He loosely, and lightheartedly, equates the technology to the childhood game "Operation," which buzzed a warning when the forceps touched the edge of the cavities that held the plastic funny bone and Adam's apple.

Minimally invasive procedures are also being used to address sinus-related issues other than classic sinusitis. "Cryotherapy is applied to the posterior nasal nerve, which contributes to dripping and congestion of the nose," says Dr. Senior. "It's a new treatment for chronic running noses, which is a problem that plagues the older population."

Dr. Senior says newer chitosan-based nasal packing materials are made from shrimp shells, which are hemostatic and, according to manufacturers of the packs, result in better healing and less scarring. "That's an interesting development I'd like to learn more about," he comments. OSM