Characterizing reduced scattering coefficient of normal human skin across different anatomic locations and Fitzpatrick skin types using spatial frequency domain imaging

Significance: Spatial frequency domain imaging (SFDI), a noncontact wide-field imaging technique using patterned illumination with multiple wavelengths, has been used to quantitatively measure structural and functional parameters of in vivo tissue. Using SFDI in a porcine model, we previously found that scattering changes in skin could potentially be used to noninvasively assess burn severity and monitor wound healing. Translating these findings to human subjects necessitates a better understanding of the variation in “baseline” human skin scattering properties across skin types and anatomical locations. Aim: Using SFDI, we aim to characterize the variation in the reduced scattering coefficient ([Formula: see text]) for skin across a range of pigmentation and anatomic sites (including common burn locations) for normal human subjects. These measurements are expected to characterize baseline human skin properties to inform our use of SFDI for clinical burn severity and wound healing assessments. Approach: SFDI was used to measure [Formula: see text] in the visible- and near-infrared regime (471 to 851 nm) in 15 subjects at 10 anatomical locations. Subjects varied in age, gender, and Fitzpatrick skin type. Results: For all anatomical locations, the coefficient of variation in measured [Formula: see text] decreased with increasing wavelength. High intersubject variation in [Formula: see text] at visible wavelengths coincided with large values of the melanin extinction coefficient at those wavelengths. At 851 nm, where intersubject variation in [Formula: see text] was smallest for all anatomical locations and absorption from melanin is minimal, significant intrasubject differences in [Formula: see text] were observed at the different anatomical locations. Conclusions: Our study is the first report of wide-field mapping of human skin scattering properties across multiple skin types and anatomical locations using SFDI. Measured [Formula: see text] values varied notably between skin types at wavelengths where absorption from melanin was prominent. Additionally, [Formula: see text] varied considerably across different anatomical locations at 851 nm, where the confounding effects from melanin absorption are minimized.