Non-Invasive Skin Imaging and Actinic Damage

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One of the most common abnormal growths due to UVB exposure is a precancerous actinic keratosis which can eventuate in squamous cell carcinoma. This actinic neoplasia is linked to UV exposures, including sunlight and indoor tanning bed exposure. Actinic neoplasia are highly prevalent in elderly patients with fair skin, and those with lower immune systems. The impact early preventative diagnosis and monitoring will have on our healthcare system is substantial, as currently the average annual cost to treat non-melanoma skin cancer is 5 billion dollars. Though often a source of considerable morbidity due to extensive surgical procedures to remove the skin cancers in the normal populations, squamous cell carcinomas are a common source of mortality in immunosuppressed populations, including solid organ transplant recipients. For prevention and accurate intervention planning, it is crucial to predict if patients have actinic neoplasia. In this study, we investigated the change in optical properties and vascular parameters to characterize skin tissue from mild photodamage to actinic keratosis. Through a clinical trial at the Wright State Physician’s Pharmacology Translational Unit, 55 test subjects over the age of 35 years with fair skin were included, and their level of skin damage was categorized both by Dermatologic analysis and Spatial Frequency Domain Imaging (SFDI). The subjects had varying levels of skin damage, especially actinic keratosis. The SFDI generated maps of absorption, scattering, hemoglobin concentrations, and tissue oxygen saturation. The Dermatologists scored the same forearm according to Global Assessment Severity Scale ranging from 0 (less severe) to 9 (the most progressed stage of skin damage). The two sets of data were then compared to find overlap in diagnosis. Photodamage stage using SFDI can be correlated to levels of scattering and hemoglobin concentration, while the dermatologist scores showed patterns of least and most progressive stages of skin damage (but on more subjective/not extreme damage there was more variance). Further methods to find the best statistical method will be explored, along with different criteria to correlate the SFDI results. Ideally, a non-invasive imaging (such as SFDI) will be used in clinical settings for frequent monitoring of patients at high risk for actinic neoplasia.