Human brown adipose tissue [15O]O2 PET imaging in the presence and absence of cold stimulus

• Published in: European journal of nuclear medicine and molecular imaging Vol. 43; no. 10; pp. 1878 - 1886
• Main Authors: u Din, Mueez, Raiko, Juho, Saari, Teemu, Kudomi, Nobu, Tolvanen, Tuula, Oikonen, Vesa, Teuho, Jarmo, Sipilä, Hannu T, Savisto, Nina, Parkkola, Riitta, Nuutila, Pirjo, Virtanen, Kirsi A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2016; Springer Nature B.V
• Subjects: Adipose Tissue, Brown - diagnostic imaging; Adipose Tissue, Brown - physiology; Adult; Body fat; Cardiology; Cold; Cold Temperature; Cold-Shock Response - physiology; Female; Humans; Imaging; Male; Medical imaging; Medicine; Medicine & Public Health; NMR; Nuclear magnetic resonance; Nuclear Medicine; Oncology; Original; Original Article; Orthopedics; Oxygen Consumption - physiology; Oxygen Radioisotopes; Positron-Emission Tomography - methods; Radiology; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity; Thermogenesis - physiology; Tissues; O]O; Brown adipose tissue; cold-induced thermogenesis; [; PET imaging; oxygen consumption; [15O]O2 PET imaging
• ISSN: 1619-7070; 1619-7089
• DOI: 10.1007/s00259-016-3364-y

Purpose Brown adipose tissue (BAT) is considered a potential target for combatting obesity, as it produces heat instead of ATP in cellular respiration due to uncoupling protein-1 (UCP-1) in mitochondria. However, BAT-specific thermogenic capacity, in comparison to whole-body thermogenesis during cold stimulus, is still controversial. In our present study, we aimed to determine human BAT oxygen consumption with [ 15 O]O 2 positron emission tomography (PET) imaging. Further, we explored whether BAT-specific energy expenditure (EE) is associated with BAT blood flow, non-esterified fatty acid (NEFA) uptake, and whole-body EE. Methods Seven healthy study subjects were studied at two different scanning sessions, 1) at room temperature (RT) and 2) with acute cold exposure. Radiotracers [ 15 O]O 2 , [ 15 O]H 2 O, and [ 18 F]FTHA were given for the measurements of BAT oxygen consumption, blood flow, and NEFA uptake, respectively, with PET-CT. Indirect calorimetry was performed to assess differences in whole-body EE between RT and cold. Results BAT-specific EE and oxygen consumption was higher during cold stimulus (approx. 50 %); similarly, whole-body EE was higher during cold stimulus (range 2–47 %). However, there was no association in BAT-specific EE and whole-body EE. BAT-specific EE was found to be a minor contributor in cold induced whole-body thermogenesis (almost 1 % of total whole-body elevation in EE). Certain deep muscles in the cervico-thoracic region made a major contribution to this cold-induced thermogenesis (CIT) without any visual signs or individual perception of shivering. Moreover, BAT-specific EE associated with BAT blood flow and NEFA uptake both at RT and during cold stimulus. Conclusion Our study suggests that BAT is a minor and deep muscles are a major contributor to CIT. In BAT, both in RT and during cold, cellular respiration is linked with circulatory NEFA uptake.