Temporal relation between temperature change and FDG uptake in brown adipose tissue.

Area of Science:

• Nuclear medicine
• Thermophysiology
• Metabolic imaging

Background:

• Brown adipose tissue (BAT) plays a role in thermogenesis.
• (18)F-fluorodeoxyglucose ((18)F-FDG) uptake in BAT is a marker of its metabolic activity.
• Previous studies suggest a link between BAT activity and ambient temperature.

Purpose of the Study:

• To investigate the temporal relationship between BAT (18)F-FDG uptake and outdoor temperature.
• To determine the duration of temperature exposure that influences BAT activity.

Main Methods:

• Retrospective review of 1,495 (18)F-FDG PET studies.
• Identification of BAT (18)F-FDG uptake by consensus of two readers.
• Correlation of BAT prevalence with average temperatures over various durations (2-60 days) prior to PET scans.

Main Results:

• A significant inverse relationship was observed between BAT prevalence and average temperatures over 1-7 days.
• Lower temperatures correlated with higher BAT (18)F-FDG uptake.
• This inverse relationship was not preserved when temperatures were averaged over 14 days or longer.

Conclusions:

• Increased (18)F-FDG uptake in BAT appears to be an acute response to cold weather.
• The effect of cold on BAT activity is time-dependent, with shorter durations (1-7 days) being more influential.
• Prolonged cold exposure does not show a consistent association with increased BAT metabolic activity.