A portable reflectometer for the rapid quantification of cutaneous haemoglobin and melanin

A portable reflectance instrument for the rapid quantification of cutaneous haemoglobin and melanin is presented. Light emitting diodes (LEDS) are used to illuminate the skin and a silicon photodiode to detect the light diffusely reflected from the surface. Reflectance measurements are made at only three wavelengths and the problems of pigment quantification consequent upon this are discussed. In addition to quantification of haemoglobin and melanin, qualitative information on the redox state of the blood may also be obtained. Measurements made on a port wine stain, which had been treated with 576 nm CW laser radiation at times between 1 and 6 months previously, provided information on the vascular response to this thermal injury. Despite the treated area visually appearing normal at 6 months post-treatment the measured levels of deoxygenated and total haemoglobin were still markedly higher than those in the adjacent uninvolved skin. The cutaneous pigment indices are insensitive to skin movement and almost all body sites are suitable for measurement.