Need to Know: How surgeons see cancer in the dark

For Dr. Sam Achilefu, the director of Washington University School of Medicine's Optical Radiology Lab, the challenge in cancer-removing surgery was clear.

“Surgeons told me that one of their problems is seeing beautiful static images of MRI and CT scans—but then when you go into the operating room you have truly nothing,” he tells “TechKnow” in this week’s episode. “It’s like walking in the dark.”

During surgery, the goal is to take out all of the cancerous tissue—and the rim of tissue around it, known as the surgical margins. After removal, this tissue is examined. If the cancer cells come to the edge of the tissue—or just too close to the tissue—additional surgery may be recommended.

According to the National Institutes of Health, between 20 and 25 percent of all breast cancer patients must undergo additional surgeries, and skin melanomas almost always require at least a secondary surgery to get a wide enough margin.

“The goal is to be able to detect very small cells,” Achilefu says. “And the current imaging systems are not capable of doing that.”

So Achilefu developed infrared goggles that are now in an early experimental phase, being tested for accuracy. And so far, they are confirming earlier tests that detected cancerous cells with high accuracy—and allowing surgeons to more precisely target what additional tissue on the margins needs to be removed.

Here’s how it works:

1. Right before surgery, the patient is injected with a green indocyanine green (ICG) dye, which binds to the proteins in the cancer cells. It’s invisible to the naked eye.

2. The doctor puts on a pair of cancer-detecting goggles.

3. A red light is pointed directly on the area where the doctor is operating. The goggles detect the area’s fluorescence.

4. From a nearby computer monitor attached to the goggles, the medical team is able to view exactly what the doctor is seeing inside the goggles in real time. The goggles allow surgeons to see cancerous cells that are as small as 1mm.

5. The surgeon removes the cancerous tissue—including tissue that may not have originally been seen in other scans.

6. The tissue is sent to the lab to confirm the presence of cancer and verify goggle accuracy.

Dr. Achilefu says, “My final goal is really to make it a routine system that we will use in all hospitals. For brain surgery, for example, where you do not have the luxury of taking out a lot of tissues and you have to be highly specific—in that particular case these goggles will be a lifesaver.”