Non-invasive estimation of skin thickness from hyperspectral imaging and validation using echography.

Background: The skin is the largest organ and is subject to the greatest exposure to outside elements throughout one׳s lifetime. Current data by the American Academy of Dermatology suggests that approximately ten people die each hour worldwide due to skin related conditions. Cancers such as melanoma are growths that originate in the epidermis. Therefore, an accurate and non-invasive method to estimate skin constitutive elements can play an important clinical role in detecting the early onset of skin tumors. It can also serve as a valuable tool for research and development in cosmetics and pharmaceuticals in general.

Methods: In our prior work, we developed a method that combined a physics-based model of human skin with machine learning and Hyperspectral imaging to non-invasively estimate physiological skin parameters, including melanosomes, collagen, oxygen saturation, and blood volume. In this work, we extend that model to also estimate skin thickness. Moreover, for the first time, we develop a protocol to test our methodology for skin thickness estimation using Ultrasound to acquire a gold standard dataset.

Results: We tested our methodology for skin thickness estimation on a dataset of 48 Hyperspectral signatures obtained in vivo from six patients under IRB at Johns Hopkins Hospital. We found mean absolute errors on the order of the Ultrasound resolution (i.e., our gold standard).

Discussion: This is the first study of its kind to validate skin thickness estimates using a gold standard. Our preliminary results constitute a proof-of-concept that hyperspectral-based methods can accurately and non-invasively estimate skin thickness in clinical settings.