Brown adipose tissue (BAT) is unique in its capability to convert chemical energy directly into heat. Active BAT increases energy expenditure and can thereby counteract obesity and insulin resistance. Currently, the imaging method of choice to assess BAT morphology and function is 18F-FDG-PET/CT which is expensive and exposes patients or healthy volunteers to ionizing radiation, thus impeding larger prospective studies.

Magnetic resonance imaging (MRI) could constitute a suitable alternative and preliminary small-scale studies are promising.

The overall aim of this research proposal is to develop reliable magnetic resonance imaging techniques to facilitate the study of brown adipose tissue in human adults, specifically in the context of endocrine disease.

Specifically, investigators want to

1. Develop a reliable MR imaging protocol for human BAT and compare BAT volume to cold induced nonshivering thermogenesis as a measure of BAT activity.
2. Assess the intra-individual variance of BAT volume measured by MRI.
3. Evaluate direct measurement of BAT temperature by functional MRI.

Inclusion Criteria:

• Healthy volunteers
• Age 18-40 years
• Body mass index (BMI): 17.5-27 kg/m²

Exclusion Criteria:

• known concomitant disease influencing thyroid hormone metabolism
• severe diseases: chronic heart failure, liver cirrhosis, kidney failure, active cancer
• known hypersensitivity to cold, e.g. primary or secondary Raynaud's syndrome
• abuse of alcohol or illicit drugs
• Women who are pregnant or breast feeding
• Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders, dementia, etc. of the participant
• Previous enrolment into the current study
• implanted device not compatible with MRI, e.g. pace maker

healthy volunteers