Researchers from the Optical + Biomedical Engineering Laboratory (OBEL) at the University of Western Australia are developing a better way to help doctors understand burn scars using optical coherence tomography (OCT).
In a recent Journal of Biomedical Optics paper, Yih Miin Liew and colleagues show a new technique to look at what is happening under the skin and understand the healing process.
Burns from fire, hot liquid, friction, radiation, and chemicals are very common, with fire-related burn injury, alone, affecting nearly 11 million people annually. The cosmetic and psychological effects of burn scarring can also be very traumatic, and identifying the best treatment for a specific scar is a critical but difficult task.
“Current assessment techniques,” says Liew, a PhD student, “can be quite subjective, making it difficult to identify if the scar is improving and also making it more challenging to identify pathological scarring early.”
Working in conjunction with the burns unit at Royal Perth Hospital, Liew has been using OCT to create images of the network of vessels interlaced throughout the scar that play a critical part in scar healing. By measuring the rate at which the speckle in the OCT images decorrelates, Liew was able to identify both the location and the depth of the blood vessels.
To allow doctors to better assess the scar, she has developed automated quantification algorithms to analyze these images, calculating both the average density of vessels and the vessel diameter.
Quantifying blood vessels
“We compared scars with corresponding healthy skin on the same patient and found that pathological scars have more blood vessels and the vessels tend to be larger,” Liew says. “We believe that a high proliferation of blood vessels drives the over-production of collagen.
“The blood vessels cause the scar to appear red, and the excess collagen causes the skin to be raised,” she says, “making it appear very different to normal skin. The imaging is allowing us to quantify the processes that occur in these sorts of pathological scars.”
Bottom figure is the depth-resolved image of the blood vessels within a small section of a scar on a patient’s forearm, as shown above. Scale bar indicates 0.5 mm. Color bar indicates physical depth in microns.
Her preliminary clinical measurements found the median diameter of superficial vessels (to a depth of 600µm) in scars to be 34µm, compared to 23µm in normal, healthy skin. The average density of vessels in scars is also higher (38%) than normal skin (22%).
By developing automated techniques to quantify the blood vessels in the scar, Liew hopes to give doctors an objective way to assess the state of the scar. Such a technique could potentially be used for longitudinal assessment of scars, allowing early assessment of whether a particular treatment is promoting scar healing, and helping guide doctors to choose better treatments.
Coauthors of the paper, “In vivo assessment of human burn scars through automated quantification of vascularity using optical coherence tomography,” are SPIE Fellow David D. Sampson, who heads OBEL; Fiona M. Wood, a plastic surgeon; Robert A. McLaughlin; and Peijun Gong.
–SPIE Fellow Ruikang K. Wang is a member of the Journal of Biomedical Optics Editorial Board.