Saving their Skin

An ingenious new NRC device uses invisible light to tell surgeons whether skin will live or die.

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For a woman who's had a mastectomy, breast reconstruction is a medical miracle – unless the transplanted skin used to build the new breast dies. Then, at least initially, the reconstructive surgery can be traumatic. This suffering could be avoided in the future thanks to new NRC technology. The spectroscopic imaging technology uses invisible near infrared (NIR) light to give surgeons the equivalent of x-ray vision to assess whether transplanted or burned skin will live or die.

The patented NIR technology has already shown its effectiveness in research trials. It was also recently profiled before a distinguished panel of business and scientific leaders in the New Technologies for Licensing category of the NRC Business Case Challenge 2006.

During breast reconstruction, a patch of skin – called a flap – is taken from elsewhere on a patient's body and used to rebuild a new breast.

During breast reconstruction, a patch of skin – called a flap – is taken from elsewhere on a patient's body and used to build a new breast. Using microvascular surgery, the flap's blood vessels are delicately sutured to existing blood vessels in the breast. If these vessels are properly connected, the flap will heal and grow. But if the blood vessel sutures are leaky or kinked, the flap, starved of blood and oxygen, will soon die. The result is a painful and ugly patch of dead skin. Unfortunately, this is a common problem: flap failure occurs in about one-tenth of the 63,000 breast reconstructions done annually in the United States.

"The main challenge with flaps is assessing immediately after the operation whether or not the microvascular surgery was successful," says Dr. Larry Leonardi, the NRC Institute for Biodiagnostics (NRC-IBD) researcher leading the development of the NIR-tissue viability technology. "There's a six-to-eight hour window in which you can re-operate without damage to the flap. After this, the flap tissue will die and the surgeon has to remove it and start from scratch."

It's during this eight-hour window that the new NRC technology really shines. Presently, plastic surgeons are able only to eyeball and use touch to determine whether or not a flap is well-supplied with blood. The same is true for burn surgeons who must rapidly assess whether burned tissue will survive or die. In half of burn cases, the burn is misdiagnosed. For physicians dealing with flaps and burns, the NRC technology gives them something they've never had before: an immediate, quantitative snap shot of the tissue's blood, oxygen and hydration levels.

Burn surgeons must rapidly assess whether burned tissue will survive or die. In half of burn cases, the burn is misdiagnosed.

The technology is based on the way that blood, haemoglobin (the part of blood that transports oxygen) and water absorb and reflect near infrared light. The system's core is a near-infrared digital camera that measures 45 different wavelengths (or "colours") of light. A tungsten halogen light is shined on the skin and the NIR digital camera records the reflected light. This information is used to produce a grey-scale digital image, or viability picture.

"For the doctor it's like reading an x-ray," says Dr. Leonardi. "It's something they can quickly understand."

Lighter regions on the digital image represent areas of skin that are well oxygenated while darker regions represent poorly oxygenated areas. So a dark image represents skin with low oxygen levels — it's dying.

A research prototype of the NRC NIR-tissue viability technology has already proven its worth through four years of testing in the busy burn unit of Toronto's Sunnybrook Hospital. After diagnosis by medical staff, the NIR-technology is used to assess the burn and compare the data to the clinical assessment.

Lighter regions on the digital image represent areas of skin that are well oxygenated while darker regions represent poorly oxygenated areas.

"We're showing that we can clearly distinguish differences in burn types and that these are predictive of whether or not skin will survive," says Dr. Leonardi, who's working in collaboration with Drs. Joel Fish and Karen Cross at Sunnybrook.

Based on the success at Sunnybrook and with earlier animal studies, the NRC team is set to begin research trials with the technology for assessing post-operative flap health in breast reconstruction surgery. This will be done in collaboration with Drs. Thomas Hayakawa and Edward Buchel at Winnipeg's Health Sciences Centre.

"The concept works, and clinicians are excited about it," says NRC's Dr. Leonardi. "Now it's time to progress from a research version to a commercial product."

The NRC research team includes Dr. Mike Sowa, Ms. Jeri Payette, Ms. Shelley Levasseur and Mr. Bernie Schattka, business officers Robert Werbowesky and Magda Kosmala, as well as Katherine Taverner from NRC-CISTI. The team is presently in licensing negotiations with a Canadian firm.

Dr. Leonardi estimates that once a licensing deal is inked, it will take about three years to develop a commercial version of the NIR tissue viability technology, validate it, and move it through the regulatory process and into the market.

For the thousands of women who experience the trauma of breast flap failure and the 80,000 people in North America who are hospitalised each year with burns, getting a commercial version of the NRC technology into the hands of plastic surgeons can't happen soon enough.

Recommended Links :

• Doing Business with NRC
• NRC's Areas of Research: Biotechnology
• NRC Institute for Biodiagnostics
  

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