Imaging tissues with a polarized light video camera

A method for imaging the superficial epidermal and papillary dermal layers of the skin is needed when assessing many skin lesions. We have developed an imaging modality using a video camera whose mechanism of contrast is the reflectance of polarized light from superficial skin. By selecting only polarized light to create the image, one rejects the large amount of diffusely reflected light from the deeper dermis. The specular reflectance (or glare) from the skin surface is also avoided in the setup. The resulting polarization picture maximally accents the details of the superficial layer of the skin and removes the effects of melanin pigmentation from the image. For example, freckels simply disappear and nevi lose their dark pigmentation to reveal the details of abnormal cellular growth. An initial clinical study demonstrated that the polarization camera could identify the margins of sclerosing basal cell carcinoma while the eye of the doctor underestimated the margin estimate. The camera identified an 11-mm-diameter lesion while the unaided eye identified a 6-mm-diameter lesion.