A cancer surgeon's primary goal in the operating room is simple, at least in theory: cut out all of the diseased tissue while leaving the healthy tissue behind. But surgeons today can't see tumor cells clearly so they don't know until long after they've left the operating room if they've achieved that goal.
"Right now the major imaging system used by a surgeon is their eyes and brain, and we all know we can't see through blood and tissue," John Frangioni, MD, PhD, of Beth Israel Deaconess Medical Center (BIDMC; Boston), told Diagnostics & Imaging Week.
Frangioni and his colleagues have spent the last eight years developing an imaging system designed to highlight cancerous tissue using near-infrared (NIR) light that penetrates through blood and tissue to allow the surgeon to more easily see what needs to be removed and what should be left alone.
GE Healthcare (Waukesha, Wisconsin) has licensed the imaging system, he said.
"This technique is really the first time that cancer surgeons can see structures that are otherwise invisible, providing true image-guided surgery," said Frangioni, who is the co-director of BIDMC's Center for Imaging Technology and Molecular Diagnostics and also an associate professor at Harvard Medical School (Boston). "If we're able to see cancer, we have a chance of curing it."
According to the researchers, the technique shows particular promise for improving surgery for breast, prostate and lung cancer, whose tumor boundaries can be difficult to track at advanced stages, they say. The Fluorescence-Assisted Resection and Exploration (FLARE) device, described at the recent annual meeting of the American Chemical Society (Washington) in Philadelphia, also can help cancer surgeons avoid cutting critical structures such as blood vessels and nerves.
FLARE is a portable system consisting of an NIR imaging system, a video monitor, and a computer. "The system has no moving parts, uses LEDs instead of lasers for excitation, makes no contact with the patient, and is sterile," Frangioni says.
The system uses special chemical dyes, called NIR fluorophores, that are designed to target specific structures such as cancer cells when the dyes are injected into patients. When exposed to NIR light, which is invisible to the human eye, the dyes or contrast agents light up the cancer cells and are shown on a video monitor.
Images of these "florescent green" cancer cells are then superimposed over images of the normal surgical field, allowing surgeons to easily see the cancer cells even in a background crowded by blood and other anatomical structures, the researcher says.
The system has been compared to the old color-by-number paint sets, only instead of coloring by numbers, it will give surgeons a way of cutting by color.
"We're training the surgeon to cut out all the green," Frangioni told D&IW.
Frangioni said he and his fellow researchers approached the development of the imaging system from a clinical perspective. He believes the reason a lot of new technology fails is because it forces the surgeon to learn something new or do something differently in the operating room. He didn't want that to happen with FLARE.
"We really built this based on clinical workflow and ergonomics," Frangioni said. "We embellished the surgery without requiring a learning curve."
With FLARE, when the surgeon looks down during the operation they'll see what they are used to seeing. But if they want to look up on the screen they'll see a color video and have image guidance that they don't currently have.
"We're just giving the surgeon the advantage of being able to see through tissue where right now they can't," he said.
The computerized technique also gives surgeons the power to control multiple viewing angles and different magnification levels through the use of a footswitch.
In preliminary studies, Frangioni and colleagues used the FLARE to visualize organs and body fluids of mice and map the lymph nodes of pigs in real time. The first human clinical trials, expected to begin this summer, involve mapping the lymph nodes of a small group of patients with breast cancer. Broader clinical use of the device could occur within five years, the researchers estimate.
"The future of the technology now is really in the chemistry," Frangioni says. "We have to develop agents for specific tumors, nerves or blood vessels we're trying to visualize."
The reason there are no tumor-specific NIR contrast agents yet is because until now there wasn't an imaging system for it. It's sort of a "chicken-and-egg" dilemma, Frangioni explained. "Why develop a system when there is no agent? Why develop an agent when there is no system? What my lab tried to do is break the cycle."
Now that GE Healthcare has licensed the imaging system, Frangioni says there will be a lot of incentive to develop an agent. How long it will take the system to be commercially available to cancer surgeons is a matter of time and money and, of course, the often-unpredictable regulatory process.
The imaging system was developed as part of a National Institutes of Health Bioengineering Research Partnership. In parallel with the device, the researchers have developed several NIR fluorophores, including organic indocyanines and inorganic/organic hybrid quantum dots.