The Promise of Near-Infrared Fluorescence

If your surgeons are asking for near-infrared fluorescence imaging, you might be wondering what the technology is used for and whether it makes sense to add it to your ORs. Let’s find out.

The bright white light on laparoscopic and robotic cameras that transmits images to surgical monitors from inside the body can brighten up a dark cavity, but beyond brightness it doesn’t provide any additional assistance or usable information to the surgeon. The ultra-high resolution of a 4K monitor can definitely enhance the quality of visualization, but on its own it doesn’t assist the surgeon beyond showing a very crisp real-life picture.

That’s where the more intelligent visualization offered by near-infrared fluorescence imaging can provide a tremendous assist to the surgeon. Using invisible near-infrared light, it identifies and delineates areas of interest. It can, for example, help a surgeon distinguish unhealthy tissue from healthy tissue through enhanced color contrast. The technology can contribute to surgeons performing more confident, accurate and comprehensive procedures, especially those involving the identification and removal of cancerous tumors. “Surgeons don’t have anything to guide them through the surgical resection of bad tissue,” says Maged Henary, PhD, an associate professor of chemistry and associate director of graduate studies at Georgia State University in Atlanta. “Sometimes surgeons like to cut a larger amount of tissue than is necessary. They don’t know really how many small parts of the tumor may have been left behind.”

Invisible to the naked eye, near-infrared light provides “lighting” for the surgeon that visible white light can’t. That lighting is enabled by a contrast agent, or fluorophore. The wavelength of the near-infrared light excites the contrast agent that has bonded with the tissue. Malignant tissue fluoresces differently than benign tissue. The imaging system can then overlay easily distinguishable colors onto a normal operative view that highlights critical areas.

The most commonly used contrast agent is indocyanine green (ICG), and the only other FDA-approved agent is methylene blue.

Arguments in favor of near-infrared fluorescence center around case reports and anecdotes, according to Christopher Schlachta, MD, a professor in the departments of surgery and oncology at Western University’s Schulich School of Medicine and Dentistry, and medical director of CSTAR (Canadian Surgical Technologies & Advanced Robotics) at London (Ontario) Health Sciences Centre. “What it’s really lacking is clinical evidence,” he says. “As often happens in the early stages of a new technology, there’s a learning curve.”

It’s a winning technology. I can tell you in my own hands, it changes the way I do surgery.
— Christopher Schlachta, MD

Indeed, experts are still trying to determine if there’s a clear clinical indication for the technology, much like what’s occurring with robotic assistance used during orthopedic and abdominal procedures. “Many key opinion leaders are advocating for the use of ICG in every case,” says Dr. Schlachta. “But we don’t really have that high level of evidence that says it makes a difference. Surgeons are going to be less inclined to randomize patients to a non-fluorescence imaging arm of a trial once they decide they really like fluorescence imaging.”

There’s really no reason not to add near-infrared fluorescence to your surgeons’ arsenal, especially if you’re upgrading OR video systems, says Dr. Schlachta. The components of a near-infrared fluorescence system are the light source, a laparoscope with a CCD chip to register the video image, an image processing unit and video monitors.

The technology is not the extravagance you might think it is, according to Dr. Schlachta. He says the cost per case ranges from a couple hundred dollars to as little as $20, depending on how you acquire your ICG supply and how you’re using it.

Dr. Schlachta’s large hospital is upgrading its video system and equipping every OR with near-infrared fluorescence imaging. He estimates the total cost for the entire project is about the same price of a single robotic surgery system.

What would Dr. Schlachta tell a fellow surgeon about near-infrared fluorescence? “This is something that’s going to change the way you do surgery,” he says. “If you don’t have it in your OR now, you’re going to be using it eventually.”

One reason for that inevitable ubiquity is the technology’s range of potential applications, which go well beyond cancer identification. Dr. Schlachta cites an example from his own experience: addressing blood flow concerns, particularly where there’s an anastomosis of the bowel or colon.

“It allows you to see whether the tissue you’re trying to put back together is perfused,” he explains. “Surgeons worry about whether anastomoses are going to heal or not, and one of the main reasons is because of ischemia.”

Dr. Schlachta says surgeons look at the color of the tissue and the amount of bleeding that occurs when the bowel is cut. “We do all these tricks to determine if the bowel is healthy when we put it back together,” he explains. “Now I can just say, ‘Give a dose of ICG,’ and that’s how I can tell that it’s perfused.”

Another benefit for Dr. Schlachta? Identifying biliary anatomy. “I had a case where I was doing a colon resection,” he says. “I used the ICG to determine the viability of the ends of the bowel that I wanted to put back together for the anastomosis.”

In that same case, it was determined the patient also needed their gallbladder removed, a procedure that was made more difficult because of very challenging anatomy. Dr. Schlachta switched on the ICG system to see the biliary structures.

“It worked perfectly,” he says. “So we used the technology for bowel profusion and biliary anatomy in the same case.”

Surgeons using near-infrared fluorescence are developing novel applications, according to Dr. Schlachta, including off-label uses not currently advocated by system manufacturers.

“Surgeons are saying, ‘This is such an awesome technology. What else can we use it for?’” says Dr. Schlachta, listing applications he’s heard about, including lymph node mapping, gynecological procedures, and surgeries that involve melanoma and identifying the parathyroid gland.

Near-infrared fluorescence continues to evolve. It’s far from a finished product, but it’s definitely a highly functional platform your surgeons can put to use now. “Great promise, minimal interruption of the workflow and super-cheap,” says Dr. Schlachta. “It’s a winning technology. I can tell you in my own hands, it changes the way I do surgery.” OSM