Evaluating the impact of melanin on spectral colouring in photoacoustic imaging

Spectral colouring severely affects quantification in photoacoustic imaging, impacting the biological interpretation of the output imaging biomarkers. Melanin is a particularly strong optical absorber in the near infrared wavelength range that exhibits substantial variation in concentration according to skin tone. Here, Monte-Carlo simulations of light transport in a computational skin phantom were carried out to establish the effects of quantifying blood oxygenation at different melanin concentrations. These results were validated with a tissue-mimicking phantom. The results demonstrated that raised melanin concentration in the epidermis significantly affects quantification of haemoglobin concentration and oxygenation with photoacoustic imaging.