Three-dimensional imaging of skin melanoma in vivo by dual-wavelength photoacoustic microscopy

Abstract

Dual-wavelength reflection-mode photoacoustic microscopy is used to noninvasively obtain three-dimensional (3-D) images of subcutaneous melanomas and their surrounding vasculature in nude mice in vivo. The absorption coefficients of blood and melanin-pigmented melanomas vary greatly relative to each other at these two optical wavelengths (764 and $584nm$). Using high-resolution and high-contrast photoacoustic imaging in vivo with a near-infrared (764-nm) light source, the 3-D melanin distribution inside the skin is imaged, and the maximum thickness of the melanoma $(∼0.5mm)$ is measured. The vascular system surrounding the melanoma is also imaged with visible light $(584nm)$ and the tumor-feeding vessels found. This technique can potentially be used for melanoma diagnosis, prognosis, and treatment planning.