Optical coherence tomography in dermatology

AIM: Optical coherence tomography (OCT) was first used in skin imaging in 1997, and since then the technology has undergone significant technological development. With its high resolution and moderate penetration depth OCT fills the imaging gap between High Frequency Ultrasound and Reflectance Confocal Microscopy. Different modalities of OCT have been developed either focusing on higher image resolution or special visualization of tissue with distinct optical properties, including collagen and blood flow. The aim of this study was to describe trends in OCT research on different dermatological diseases and review the results.

METHODS: Pubmed, EMBASE, Web of science, Google Scholar and Cochrane databases were searched for the terms "optical coherence tomography", "OCT" and "dermatology" including English articles on studies of human skin tissue in vivo, finding 117 studies of original research and including 64 studies based on predefined criteria and year of publication.

RESULTS: In dermatology, most studies of OCT were on non-melanoma skin cancer followed by pigmented lesions, inflammatory skin diseases, nails diseases and anatomical and physiological features investigated by OCT. In non-melanoma skin cancer diagnostic OCT criteria have been proposed and recent studies have shown a high diagnostic accuracy of 87.4% and identified objective scoring criteria for diagnosing non-melanoma skin cancer. In pigmented lesions, morphological features for differentiation of benign naevi and malignant melanoma have also been suggested, though only included small samples of malignant lesions were used in most studies. Results were further limited by a high light absorption in melanin at the used wavelenghts. Studies on skin inflammation have described morphological features of different inflammatory responses such as allergic reactions, but remain at a preliminary stage. Regarding the anatomical and physiological features of the skin, OCT studies have mainly focused on measuring epidermal thickness and morphological changes in the acute response to UV-radiation.

CONCLUSION: OCT research in dermatology has undergone significant developments since its first application in 1997. The rising demand for non-invasive monitoring of skin disorders and treatment outcomes emphasize the need for further advances in the field of non-invasive imaging. Combining OCT with other technical modalities that enable quantitative measurements of e.g. blood flow or light reflectance in tissue may aid the usability of OCT in a clinical setting.