(A) Transversal PET (left panel), CT (middle panel), and fusion scan (right panel) views of the cervicothoracic junction in one of the participants. Red circles denote supraclavicular BAT. (B) Fractional (Ki) and (C) net (Km) glucose uptake in cervicothoracic tissues. (D) Coronal view (postero-anterior projection) of whole-body 18FDG uptake during cold exposure. *P < 0.05 versus BAT, ANOVA with Dunnett’s post-hoc test.