RecruitingDevice studyPhotoacoustic/Ultrasound Imaging of Brown Adipose Tissue ActivityThe goal of this study is to develop a novel, non-invasive, real-time photoacoustic imaging (PAI) technology for quantifying brown adipose tissue (BAT) and to investigate the differences in BAT morphology and metabolic function between healthy individuals and patients with metabolic syndrome. The main questions it aims to answer are: 1. Can PAI technology quantify BAT metabolic function and establish standardized PAI parameters for BAT assessment? 2. Can PAI parameters distinguish the BAT characteristics of healthy volunteers from patients with metabolic syndrome? Both healthy adults and patients diagnosed with metabolic syndrome will be recruited. Participants will undergo PAI scans of BAT region under normal conditions and after cold exposure to assess BAT activation. The ultimate goal is to validate this radiation-free PAI method as a convenient and effective tool for evaluating BAT metabolism, potentially aiding in early diagnosis and treatment monitoring of metabolic syndrome.