Applicability of Supraclavicular Oxygenated and Total Hemoglobin Evaluated by Near-Infrared Time-Resolved Spectroscopy as Indicators of Brown Adipose Tissue Density in Humans

Brown adipose tissue (BAT) may potentially be used in strategies for preventing lifestyle-related diseases. We examine evidence that near-infrared time-resolved spectroscopy (NIR(TRS)) is capable of estimating human BAT density (BAT-d). The parameters examined in this study are total hemoglobin [total-Hb](sup), oxygenated Hb [oxy-Hb](sup), deoxygenated Hb [deoxy-Hb](sup), Hb O(2) saturation (StO(2sup)), and the reduced scattering coefficient in the supraclavicular region (μ(s)’(sup)), where BAT deposits can be located; corresponding parameters in the control deltoid region are obtained as controls. Among the NIR(TRS) parameters, [total-Hb](sup) and [oxy-Hb](sup) show region-specific increases in winter, compared to summer. Further, [total-Hb](sup) and [oxy-Hb](sup) are correlated with cold-induced thermogenesis in the supraclavicular region. We conclude that NIR(TRS)-determined [total-Hb](sup) and [oxy-Hb](sup) are useful parameters for evaluating BAT-d in a simple, rapid, non-invasive manner.