Metabolic rate of oxygen in the brown adipose tissue (BAT) using [15O]O2-PET
Model for BAT [15O]O2-PET
Muzik et al. (2012, 2013) have measured oxygen consumption and oxygen extraction rate (OER, or oxygen extraction fraction, OEF) in BAT applying the dynamic method that has been developed and validated for the brain (Mintun et al., 1984; Huang et al., 1986; Hattori et al., 2004). This approach involves three PET studies: a single-inhalation [15O]O2, an intravenous bolus injection of [15O]H2O, and a single-inhalation of [15O]CO, and enables estimation of perfusion, vascular volume fraction in tissue (VB), metabolic rate of oxygen (MRO2), and OER. Arterial input function is required, but in BAT studies it can be measured from the PET image (Muzik et al., 2013). However, at least one arterial blood sample is required in [15O]O2 study to determine the amount of recirculating [15O]H2O (Mintun et al., 1984).
PET/CT scan with [18F]FDG is required to determine whether subject has marked brown adipose tissue (BAT) deposits or not, and to define regions-of-interest (ROIs) for BAT and white adipose tissue (WAT) in the cervical and supraclavicular areas (Muzik et al., 2012 and 2013). CT density and [18F]FDG SUV50-60min were used to draw the ROIs, which were then transferred to 15O images, and regional time-activity curves (TACs) were calculated (Muzik et al., 2012 and 2013).
Frackowiak RS, Lenzi GL, Jones T, Heather JD. Quantitative measurement of regional cerebral blood flow and oxygen metabolism in man using 15O and positron emission tomography: theory, procedure, and normal values. J Comput Assist Tomogr. 1980; 4(6): 727-736.
Hattori N, Bergsneider M, Wu H-M, Glenn TC, Vespa PM, Hovda DA, Phelps ME, Huang S-C. Accuracy of a method using short inhalation of 15O-O2 for measuring cerebral oxygen extraction fraction with PET in healthy humans. J Nucl Med. 2004; 45: 765-770.
Huang S-C, Feng D, Phelps ME. Model dependency and estimation reliability in measurement of cerebral oxygen utilization rate with oxygen-15 and dynamic positron emission tomography. J Cereb Blood Flow Metab. 1986; 6: 105-119.
Mintun MA, Raichle ME, Martin WRW, Herscovitch P. Brain oxygen utilization measured with O-15 radiotracers and positron emission tomography. J Nucl Med 1984; 25; 177-187.
Muzik O, Mangner TJ, Granneman JG. Assessment of oxidative metabolism in brown fat using PET imaging. Front Endocrinol (Lausanne). 2012;3:15.
Muzik O, Mangner TJ, Leonard WR, Kumar A, Janisse J, Granneman JG. 15O PET measurement of blood flow and oxygen consumption in cold-activated human brown fat. J Nucl Med. 2013; 54(4):523-531.
Ohta S, Meyer E, Thompson CJ, Gjedde A. Oxygen consumption of the living human brain measured after a single inhalation of positron emitting oxygen. J Cereb Blood Flow Metab 1992; 12: 179-192.
Schulz TJ, Tseng Y-H. Brown adipose tissue: development, metabolism and beyond. Biochem J. 2013; 453: 167-178.
Updated at: 2013-06-13
Written by: Vesa Oikonen