Blood oxygen saturation estimation in transilluminated images of skin lesions

Estimating the oxygen saturation of blood surrounding skin lesions is critical for the early detection of skin cancer and malignancy such as melanoma. Through multispectral transillumination of the skin, a set of images can be obtained which helps visualize areas of subsurface absorption due to chromophores such as melanin, hemoglobin, and deoxyhemoglobin. To relate pixel intensity in these images to spatially located absorption coefficient values, we develop a correction factor to Beer´s law, estimated through a Monte Carlo simulation of light propagation in skin, which takes into account the specific geometry of our transillumination imaging apparatus. We then use this relation on the multispectral imaging set for chromophore separation and oxygen saturation estimation. The separation method is validated through Monte Carlo simulation, as well as on a skin phantom. Results show that subsurface oxygen saturation can be reasonably estimated with good implications for the reconstruction of 3D skin lesion volumes using transillumination towards early detection of malignancy.