A Short-Wave Infrared Camera Can Assess Burns. Here’s Why It’s Important

A novel camera could change the way clinicians determine burn depth—and make the assessment less invasive

Dr. Benjamin Levi isn’t content with just fixing things. An assistant professor of surgery and director of the Burn, Wound, and Regenerative Medicine Lab, he’s a classic surgeon-scientist, conducting research to improve the fixes. 

A recent paper in Wound Repair and Regeneration shared findings from a study by Dr. Levi and colleagues that showed a short-wave infrared (SWIR) camera could accurately assess tissue viability after a burn injury. The camera made the assessments by measuring tissue moisture after different severities of burns. 

The method provides a more rapid, less invasive and more accurate way to evaluate burns so that surgeons can make more informed, objective decisions about courses of treatment: Whether to debride tissue, to let tissue heal on its own or some combination of both. It also points to potentially better outcomes; current approaches to assessing burn depth and severity result in misdiagnosis of injury depth in more than 40 percent of cases.

Here are some key questions about the study and takeaways from the findings. 

Why
What prompted this research?

During Levi’s fellowship at Massachusetts General Hospital, his fellowship director, Shawn Fagan, pointed out that taking visual note of tissue moisture was a good way to assess burns. The drier the tissue appeared, the worse and deeper the burn probably was. 

As good as the correlation was, the method of assessment was imprecise and subjective. That nagged at Levi and he later decided to pursue ways to objectively and precisely measure moisture as a surrogate for tissue viability with his team. 

“There’s no way to objectively look at moisture. The fact that we’re only right on guessing at burn depth 60 percent of the time means we’re not much better than flipping a coin, so if there was a better way to quantify that, we’d be much better off,” Levi said. 

Further, existing methods of determining tissue health via biopsy are impractical, expensive, invasive, and subject to sampling errors, the study points out. 

Tech
Why an infrared camera?

SWIR cameras have been used in other scientific and commercial applications to assess moisture; Dr. Levi and colleagues had seen literature describing cameras used to assess forest fires and predict where a fire might spread. He was also aware that cosmetics companies had used SWIR technology to prove the efficacy of facial moisturizers and that the meat industry used them to assess whether meat had spoiled. 

Based on these previous studies, Dr. Levi and colleagues began to build and validate a SWIR technology to objectively quantify burn depth. 

Over the course of the study, the team evaluated the reflectance of light from agar slabs to establish a baseline, then moved to murine and porcine models.

Twist
Were there surprises from the study?

Levi and his colleagues had gone into the study thinking one single wavelength would be the most accurate. As it turned out, they weren’t correct. 

 “This required us to look at across multiple wavelengths within the SWIR spectrum,” Levi said. 

Within the SWIR range(1,000–2,500 nm), the team found that reflectance of light depends on several wavelengths of the images and the burn depths and that looking at multiple wavelengths across various burn types provided the best assessment.

Team
What collaboration went into this work?

Bo Schembechler wasn’t the only one who understood the importance of a team. 

That’s what it took to develop the camera, the camera, the camera. 

Levi’s group collaborated with Omer Berenfeld, PhD and Sergey Mironov, PhD from Cardiology and Emeritus Professor of Chemistry Michael Morris to build and refine the camera’s optics. (Levi had previously tapped Morris for his expertise when working on a study about heterotopic ossification in bone.)

The base of the camera was adapted from one made for industrial purposes and the engineering department was engaged to optimize the lighting for consistency, enable it to assess different wavelengths and develop a lever arm for it to allow for use in the operating room. 

Benefit
How does this new method move the needle?

Levi said effective application of the device should decrease lengths of hospitals stays and decrease complications.

Why?

A more timely, precise, and less invasive diagnosis of burn severity means a patient can avoid unnecessary surgery, or get the surgery they need quicker. 

“The risk of doing surgery when it’s not needed is that you give someone a scar they didn't need. If you don’t do surgery when they need it, they get infections and scar contractures,” Levi said. 

Levi also thinks that even though the technology is new, it could ultimately be more cost-effective than current established models of burn assessment. 

“Ultimately if we’re wrong on our to debride/not debride decision, the patient ends up in the hospital longer or having surgery they shouldn't have had,” which drives up episode costs, Levi said.

Next
What’s on the horizon for the device and method?

Levi said he and his collaborators are continuing to optimize the design of the camera. 

They’re also looking for more efficiencies, such as applying artificial intelligence to distinguish between live and dead tissue, he said.

Finally, the group is looking ahead to a laser projection-driven device to guide surgeons in debridement once burns are accurately assessed by the camera. The concept would involve the laser projecting data from the SWIR camera in real time onto the patient, helping surgeons decide which areas to debride and which to allow to heal. 

And, just as Levi looked to forest fires and cosmetics for inspiration for a burn-specific application of short-wave infrared cameras, others may look to the burn application for other clinical applications. Levi sees potential uses in diabetic and pressure wounds, for example. 

 

By Colleen Stone

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