Brown Adipose Tissue Activity and NAFLD Progression

This was a single-center, non-interventional observational study designed to investigate the relationship between brown adipose tissue (BAT) activity and NAFLD-related clinical and metabolic characteristics.

Participants who had already undergone 18F-FDG PET/CT examinations for clinical purposes were recruited. No additional PET/CT examination was performed for this study. Existing PET/CT imaging data were collected and analyzed to assess BAT activity. The maximum standardized uptake value (SUVmax) was used as an imaging parameter to evaluate BAT activity.

Peripheral blood samples were collected from participants for plasma analysis. Plasma samples were used to investigate circulating factors associated with BAT activity and their relationships with NAFLD-related clinical and metabolic parameters.

This study did not assign any investigational drug, device, behavioral intervention, or additional imaging examination. Only previously acquired PET/CT imaging data, peripheral blood samples, and relevant clinical information were collected and analyzed.

Inclusion criteria

• Patients who had undergone clinically indicated 18F-FDG PET/CT examination.
• Willing and able to provide written informed consent and comply with the study procedures.
• No long-term use of medications such as glucocorticoids or lipid-lowering drugs; no smoking or excessive alcohol consumption (alcohol intake <20 g/day).
• High BAT activity group: BAT SUVmax ≥2.0, with clear BAT activation in the cervical, shoulder, or supraclavicular regions on PET/CT.
• Intermediate BAT activity group: 1.0 ≤ BAT SUVmax <2.0.
• Low BAT activity group: BAT SUVmax <1.0 or no detectable BAT distribution on PET/CT.

Exclusion criteria

• Use of medications affecting metabolism within the previous 3 months, such as beta-blockers or thyroid hormones.
• Contraindications to PET/CT examination, such as claustrophobia or contrast-agent allergy.
• Pregnancy or breastfeeding.