Optical Imaging as Auxiliary Tool in Skin Cancer Diagnosis

Abstract

Clinical detection of early malignant and premalignant skin lesions is not simple due to their similar features with the more common benign lesions. The traditional skin cancer screening is based on careful whole body visual inspection, and if a suspected lesion is noticed, further examination with biopsy is required. Visual examination relies heavily on the experience and skills of the physician to identify and delineate the initial changes related to carcinogenesis and cancer progression. White light dermatoscope is the most used conventional tool for skin cancer screening, used by dermatologists for a magnified visualization of the skin. Optical imaging at widefield and microscopic levels has been presented as clinical tools for aiding lesion detection and discrimination. Optical techniques are non-invasive, with fast response through an in situ interrogation, and are potentially sensitive to biochemical and structural changes presented in skin cancer development. For skin cancer diagnostics the main used techniques are: widefield imaging, optical spectroscopy and microscopy imaging. Widefield imaging allows the examination of large areas and has the potential of improving detection of occult lesions, margin delimitation, and of guiding biopsy site determination. Optical spectroscopy presents more detailed information on tissue composition, through the light intensity for each collected emission wavelength, which might be later correlated to specific biomolecules. Microscopy imaging has a main advantage of the evaluation of the tissue characteristics at cellular level, but only a small fraction of the lesion volume is interrogated. Distinct optical techniques offer different tissue/cellular information that is complimentary, even though for cancer screening, widefield optical imaging may represent the first best option, when compared to point spectroscopy or optical microscopy. The combination of information from different imaging modalities has the potential of revealing tissue features resulting in an improved diagnostic performance, due to their distinct provided tissue information. In this chapter an overview of the optical clinical methods and the instruments developed for skin cancer detection of published studies will be discussed.