High prevalence of brown adipose tissue in adult humans

Context: Positron emission tomography (PET)-computed tomography (CT) has identified metabolically active supraclavicular fat in adult humans based on uptake of labeled glucose and confirmed to be brown adipose tissue (BAT) histologically. However, PET-CT has estimated a prevalence of BAT as low as 5% in adult humans, casting doubt on its significance. The true prevalence of BAT is unknown because of the suboptimal sensitivity of standard PET-CT. Objective: The objective of the study was to determine whether BAT is present in PET-negative supraclavicular fat. Design: This was a prospective cohort study. Setting: The study was conducted at a tertiary referral hospital. Patients: Seventeen patients who underwent preoperative PET-CT for staging of head and neck malignancy participated in the study. Main Outcome: The main outcome was signature BAT gene transcripts and protein in biopsies of supraclavicular fat with sc fat as negative control. Results: PET-CT was positive in three and negative in 14 patients. P...