J Clin Invest.
11C time-radioactivity curves over the first 500 seconds of acquisition after 11C-acetate injection at room temperature (red) and during cold exposure (blue) in (A) blood in the aorta, (B) supraclavicular BAT, (C) subcutaneous adipose tissue, (D) longus colli, (E) trapezius, and (F) deltoid. 11C time-radioactivity curves were different during cold exposure from those at room temperature in BAT (2-way ANOVA, P = 0.05; interaction with time, P < 0.001) and in longi colli (2-way ANOVA, P = 0.02; interaction with time, P < 0.001), but not in other organs. Monoexponential decay slope from peak tissue 11C activity (11C-acetate k) in (G) supraclavicular BAT and (H) longus colli. (I) BAT radio density by CT.