Evaluation of Brown Adipose Tissue Using Near-Infrared Time-Resolved Spectroscopy

Abstract

Human brown adipose tissue (BAT) activity (SUV_max) has been typically evaluated by ¹⁸F-fluorodeoxy glucose (FDG)–positron emission tomography (PET) combined with computed tomography (CT). In this study, the objective was to detect human BAT by near-infrared time-resolved spectroscopy (NIR_TRS), a noninvasive and simple method for measuring total hemoglobin concentration [total-Hb] and reduced scattering coefficient (μs′) in the tissue. The [total-Hb] in the supraclavicular region of the BAT (+) (SUV_max ≥ 2.0) group was 95.0 ± 28.2 μM (mean +/− SD), which was significantly higher than that of the BAT (−) (SUV_max < 2.0) group (52.0 ± 14.8 μM), but not in other regions apart from the BAT deposits. The μs′ in the supraclavicular region of the BAT (+) group was 8.4 ± 1.7 cm⁻¹, which was significantly higher than that of BAT (−) group (4.3 ± 1.0 cm⁻¹), but not in other regions. The area under the receiver operating characteristic curve closest to (0, 1) for [total-Hb] and μs′ to discriminate BAT (+) from BAT (−) was 72.5 μM and 6.3 cm⁻¹, respectively. The sensitivity, specificity, and accuracy for both parameters were 87.5, 100, and 93.3 %, respectively. Our novel NIR_TRS method is noninvasive, simple, and inexpensive compared with FDG-PET/CT, and is reliable for detecting human BAT.