Optical mapping of nonmelanoma skin cancer

Abstract

More than two million cases of nonmelanoma skin cancers are diagnosed every year. Therefore, there is a strong need for practical, reliable, rapid, and precise methods for tumor delineation, to guide surgery and other treatments of skin cancer. Once developed, such methods may be useful for squamous cell carcinomas of other organs. Non-invasive optical imaging techniques including polarization sensitive reflectance and fluorescence imaging were evaluated for the demarcation of nonmelanoma skin tumors. Thick freshly excised tumor specimens obtained from Mohs surgery were used for the experiments. Imaging was performed using linearly polarized incident light in the visible and near infrared spectral range from 577 nm to 750 nm. Non-toxic absorbing and fluorescent dyes (Toluidine Blue O, Methylene Blue) were employed to enhance tumor contrast in the images. The images were acquired using the remitted light polarized in the directions parallel and perpendicular to the polarization of incident light. Reflectance and fluorescence polarization images were evaluated. The data were processed and analyzed for dependence of the remitted light polarization on the tissue type (cancerous/normal). The data obtained so far from fresh tumor specimens in vitro using dye-enhanced polarized light reflectance, and exogenous fluorescence polarization imaging suggest that optical mapping can become a valuable guidance tool in nonmelanoma cancer surgery.