Contrast mechanisms in pump-probe microscopy of melanin

Pump-probe microscopy of melanin in tumors has been proposed to improve diagnosis of malignant melanoma, based on the hypothesis that aggressive cancers disaggregate melanin structure. However, measured signals of melanin are complex superpositions of multiple nonlinear processes, which makes interpretation challenging. Polarization control during measurement and data fitting are used to decompose signals of melanin into their underlying molecular mechanisms. We then identify the molecular mechanisms that are most susceptible to melanin disaggregation and derive false-coloring schemes to highlight these processes in biological tissue. We demonstrate that false-colored images of a small set of melanoma tumors correlate with clinical concern. More generally, our systematic approach of decomposing pump-probe signals can be applied to a multitude of different samples. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

Pump-probe microscopy is proposed to improve the diagnosis of malignant melanoma by analyzing the signals of melanin. The study decomposes the signals and identifies the molecular mechanisms most susceptible to melanin disaggregation, creating false-colored images to highlight these processes in biological tissue. The results demonstrate a correlation between false-colored images of melanoma tumors and clinical concern, and the approach can be applied to other samples.