Off the Beaten Path in Oncology: Active Brown Adipose Tissue by Virtue of Molecular Imaging

Abstract

Brown Adipose Tissue (BAT) is considered beneficial in diabetes and obesity, but it can also have negative effects such as its implication in tumours’ pathogenesis and the development of Cancer-induced Cachexia. Since 18F-FDG PET/CT is a common molecular imaging modality used in cancer assessment, we aim to study the 18F-FDG BAT biodistribution in oncological patients and look for possible correlations between BAT activity and different malignancies as well as the patient’s weight status. After analysing the total number of oncological 18F-FDG PET/CT scans between 2017 and 2021, we selected patients with active BAT. Based on their BMI, the selected patients were divided into nonobese (NO) vs. overweight and obese (OOB). OOB SUVmaxlean body mass(LBM) had the highest mean values in supraclavicular, latero-cervical, and paravertebral vs. mediastinal and latero-thoracic localisations in NO. BMI was positively correlated with latero-cervical and supraclavicular SUVmax(LBM) but negatively correlated with latero-thoracic and abdominal SUVmax(LBM). Considering the age of the patients, SUVmax(LBM) decreases in the latero-cervical, paravertebral, and abdominal regions. In addition, the males presented lower SUVmax(LBM) values. SUVmax(LBM) was not affected by the treatment strategy or the oncological diagnosis. To conclude, it is mandatory to take into consideration the BAT particularities and effects on weight status in order to optimise the clinical management of oncological patients.

Are MTV and TLG Accurate for Quantifying the Intensity of Brown Adipose Tissue Activation?

“…In adult humans, the existence of functional BAT was primarily recognised through the application of 18 FDG PET/CT [9,42]. When it comes to glucose metabolism, it appears that the very high metabolic activity of normally metabolically inactive fat tissue is what finally convinced the scientific community to recognise BAT as an organ of interest for energy balance, along with its possible therapeutic effects on obesity and type 2 diabetes [9,14,43].…”

“…Since it produces a range of adipokines, BAT also functions as an endocrine tissue [13,14]. In addition to controlling vascular function and coagulation, BAT-adipokines play a role in the regulation of nutrition behaviour, insulin sensitivity, energy homeostasis, glucose and lipid metabolism, and adipogenesis [15][16][17].…”