Kinetic metrics of 18F-FDG in normal human organs identified by systematic dynamic total-body positron emission tomography

Abstract

To investigate the kinetic metrics of 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) in normal organs by using dynamic total-body (TB) positron emission tomography (PET). Dynamic TB-PET was performed for nine healthy volunteers. Time-to-activity curves (TACs) were obtained by drawing regions of interest in the organs. A two-tissue compartment model was fitted for each tissue TAC. Constant rates, including k1, k2, and k3, and the metabolic rate of FDG (MRFDG) were obtained. The parameter statistics, including the average, standard deviation, coefficient of variance, and inter-site and inter-individual variances, were compared. Constant rates and MRFDG varied significantly among organs and subjects, but not among sides or sub-regions within an organ. The mean k1 and k2 ranged from 0.0158 min−1 in the right lower lung to 1.1883 min−1 in the anterior wall of the left ventricle (LV) myocardium and from 0.1116 min−1 in the left parietal white matter to 4.6272 min−1 in the left thyroid, respectively. The k3 was lowest in the right upper area of the liver and highest in the septal wall of the LV myocardium. Mean MRFDG ranged from 23.1696 μmol/100 g/min in the parietal cortex to 0.5945 μmol/100 g/min in the lung. Four groups of organs with similar kinetic characteristics were identified: (1) the cerebral white matter, lung, liver, muscle, bone, and bone marrow; (2) cerebral and cerebellar cortex; (3) LV myocardium and thyroid; and (4) pancreas, spleen, and kidney. The kinetic rates and MRFDG significantly differed among organs. The kinetic metrics of FDG parameters in normal organs can serve as a reference for future dynamic PET imaging and research.