Dual-Angle Photoacoustic Depth Sensing of Congenital Melanocytic Nevi

The removal of giant congenital melanocytic nevi can be important in plastic surgeries. For aesthetic reasons, the precise and noninvasive detection of the depth of epidermal melanin infiltration before treatment is essential. Therefore, we proposed photoacoustic technology to provide both accurate and safe depth detection. It is novel that two ultrasonic transducers were applied to collect dual-angle photoacoustic signals. Also, the new indicator k-value was introduced to demonstrate the relationship between melanin depth and photoacoustic signals. Ex vivo experiments were conducted with human skin samples, and the results revealed that the deeper the melanin is, the larger k-value the sample has. It is safe to conclude that photoacoustic sensing for depth detection can be quite promising in clinical applications.