An assessment of burn depth is a key step in guiding the treatment of patients who have sustained thermal injuries. Polarization-sensitive optical coherence tomography (PS-OCT) might eventually provide the physician with a quantitative estimate of actual burn depth. Burns of various depths were induced by contacting rat skin with a brass rod preheated to 75 degrees C for 5, 15, or 30 s. Thermal injury denatured the collagen in the skin, and PS-OCT imaged the resulting reduction of birefringence through the depth-resolved changes in the polarization state of light propagated and reflected from the sample. Stokes vectors were calculated for each point in the PS-OCT images and the reduction in the rate of phase retardation between two orthogonal polarizations of light (deg/microm) was found to show a consistent trend with burn exposure time. PS-OCT is a noninvasive technique with potential to give the physician the information needed to formulate an optimal treatment plan for burn patients.

Burn depth determination is a critical factor in the treatment of thermal injury. We have developed a technique, polarization sensitive optical coherence tomography (PS-OCT), to assess burn depth non-invasively. Thermal injury denatures collagen in human skin. PS-OCT is able to measure the resulting reduction in collagen birefringence using depth resolved changes in the polarization of light propagated and reflected from the sample. In a previous study, we used a free space PS-OCT system at 850 nm to image in vivo the skin of rats burned for various amounts of time. Using a high-speed system at 1.3 micrometers has the advantages of greater depth penetration and reduction of motion artifacts due to breathing and small movements of the animal. Stokes vectors were calculated for each point in the scans and the relative birefringence was determined using different incident polarization states. Birefringence was correlated with actual burn depth determined by histological analysis. Our results show a marked difference between normal tissue and even the slightest burn, and a consistent trend for various degrees of burns.