Optical coherence tomography (OCT) in examining human nails of subjects with different skin types

Nail unit melanoma (NUM) is a rare form of melanoma which has one of the highest mortality rates among melanoma subtypes, largely due to challenges in early diagnosis. The conventional benchmark for diagnosing NUM is a biopsy, which is invasive, may yield inconclusive histology, and can lead to nail dystrophy. The complexity of nail anatomy, the risk of injury from the biopsy itself, and the potential for NUM to be amelanotic complicate diagnosis and often delay treatment, resulting in poor prognoses. Swept source Optical Coherence Tomography (ss-OCT) is a non-invasive imaging technique that can acquire images up to 1 to 2mm deep. For this reason, ss-OCT offers an attractive alternative to biopsies for NUM. ss-OCT does not image malignancies directly, but can rely on AI-based image analysis of OCT images to identify melanoma. A necessary precursor to developing a computational core for any population-wide image analysis is to determine whether the images acquired contain racial or ethnic differences which will need to be included in the computational design. This is particularly important for NUM because unlike cutaneous melanoma, NUM is equally prevalent in fair skin and skin of color. The purpose of this study is to investigate whether ss-OCT could be used as a minimally invasive diagnostic method for nail unit melanoma (NUM) by analyzing whether there are inherent differences in OCT images from subjects with a range of skin tones. We captured ss-OCT B-scans of the left and right index finger, thumb, and big toe from individuals with skin tones ranging from I to VI on the Fitzpatrick Scale. We found no significant differences in nail morphology across individuals of different skin tones, as determined by comparing nail plate thickness. Based on these findings, OCT shows promise as a reliable method for assessing nail morphology in individuals of all skin tones. Understanding the nail’s morphology through OCT imaging, along with the observed consistency across skin tones, is an important precursor for development of ss-OCT as a diagnostic tool for nail unit cancers.