Multiple imaging and quantification approaches for BAT are available. The most often used technique is PET/CT with [18F]FDG. Its broad field of application as well as its use in clinical routine makes this tracer very popular, also in the field of BAT imaging. Nevertheless [18F]FDG has a huge disadvantage: it is a glucose based tracer. Although [18F]FDG was able to visualize BAT and to show increased metabolic activity in cold exposed animals and humans, lipids in the form of FAs are the main metabolized substance class. Therefore it is impossible to calculate BAT's total metabolic activity.

At first FA based tracers, such as [18F]FTHA or [123I]BMIPP, were used to quantify BATs its demand of FAs. However, this method does not completely reflect the situation in vivo where FAs are transported as TGs incorporated in TRLs towards BAT. Therefore the aim of this dissertation was to synthesize a radiolabeled TG and to incorporate

it into a TRL which than can be applied in vivo. To our understanding this would come closest to the in vivo situation and will probably help to understand BATs role in whole body energy expenditure. Additionally such a tracer would also be useful for other applications (e.g. fatty liver disease, obesity and fatty acid metabolism in general).