Abstract
Purpose: The aim of this study was to evaluate a microwave radiometer system in the non-invasive assessment of activated and non-activated brown adipose tissue (BAT). Materials and Methods: In this prospective study, microwave radiometry (MRAD) and fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with computed tomography (CT) were performed on nineteen participants who underwent a cold intervention to activate BAT. The cold intervention involved the participant intermittently placing their feet on a cold block of ice while sitting in a cool room. Participants exhibiting BAT activity on PET/CT were scanned again following a BAT minimization protocol (exposure to a warm room and a 20 mg dose of propranolol). Microwave radiometry was performed every five minutes for two hours prior to FDG PET/CT imaging during both warm and cold interventions. Results: Active BAT was identified using FDG PET/CT in 11 of 19 participants. In 10 of 11 participants with active BAT, radiometry measurements collected during the cold study were modestly, but significantly higher on points located over areas of active brown fat on FDG PET/CT, than in points not exhibiting BAT activity (P < 0.01). This difference lessened during the warm studies: radiometry measurements in 7 of 11 participants did not differ significantly between the same set of points. Conclusion: Passive microwave radiometry was shown to be feasible and, with substantial improvements, has the potential to non-invasively detect active brown adipose tissue without a radiotracer injection.
- Copyright © 2018 by the Society of Nuclear Medicine and Molecular Imaging, Inc.