Brown adipose tissue (BAT) is a metabolically active tissue whose activity in adults is most commonly assessed using positron emission tomography/computed tomography with [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG PET/CT). Due to the limitations of the reference method, there is a need for non-invasive methods suitable for repeated measurements.
The aim of this master’s thesis was to develop a standardized cooling protocol and to perform a metrological evaluation of an infrared thermography (IRT) method for monitoring BAT activity. The thermographic response of the supraclavicular region was evaluated using two parameters, IRT area and IRT integral, and the results were compared with [¹⁸F]FDG PET/CT. To improve measurement comparability, a relative temperature threshold, spatial calibration, and standardized measurement conditions were applied.
A total of 34 premenopausal women with obesity, treated with tirzepatide or placebo, were included in the randomized, placebo-controlled TABFAT clinical trial. Thermographic measurements were performed in 33 participants, as one participant was not measured due to an acute respiratory infection. The changes in both thermographic parameters following the intervention differed significantly between the two groups. In the tirzepatide group, both IRT area and IRT integral increased, whereas they decreased in the placebo group. In all participants whose BAT status on [¹⁸F]FDG PET/CT changed between visits, the thermographic response changed in the corresponding direction.
The results indicate that the developed IRT method has potential for the non-invasive and quantitative monitoring of changes in the thermographic response of the supraclavicular region associated with BAT activity in the same individual over time.
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