Body-Site Variation of Skin Autofluorescence

Abstract

The body-site variation of skin autofluorescence was monitored in vivo in order to characterize individual contributions to the overall signal. Body sites having a range of chronic solar exposure were selected. The site-to-site spectral data sets were acquired from thirteen subjects. Incident light of 325-nm wavelength was used to excite fluorescence, observed between 360 nm and 570 nm. Principal factor analysis coupled with alternating least-squares optimization of within-subject body-site dependence revealed that two factors accounted for all of the body-site spectral variability. The factors were virtually the same for all subjects. The spectra were interpreted in terms of collagen cross-links and NADH. The body-site variation of component scores (relative concentrations) exhibited a consistent pattern between subjects. The factor assigned to collagen had highest scores at protected body sites; in contrast, NADH had highest scores at more exposed sites.