Brief Summary:

Photoacoustic imaging (PAI) is an emerging method which combines light and ultrasound to assess the blood content and oxygenation of the body. Light is absorbed by the blood, leading to the generation of ultrasound, from which the levels of oxygen can be derived. This high sensitivity to blood has seen it applied in multiple clinical trials for the assessment of a number of conditions including breast cancer assessment. However, the accuracy of the measurements and image quality is known to decrease as you look deeper into the body because light intensity decreases. Melanin in the skin is known to absorb light very strongly and so there is considerable concern that this may bias measurements made in people with darker skin tones compared to those with lighter skin tones. In this pilot study, we intend to recruit volunteers with a wide range of skin tones and vitiligo. We will scan a number of blood vessels and muscles using PAI and evaluate the photoacoustic measurements of blood content and oxygenation to identify, and ultimately correct for, biases in advance of further clinical studies.