Normal 18F-FDG cerebral uptake pattern with PET/MRI imaging

3032 Objectives: The study aims to obtain the normal 18F-FDG uptake in brain cortex regions with objects of various ages and explore the cerebral uptake pattern on an integrated TOF PET/MR system. Methods: Data of 479 objects who have done integrated 18F-FDG PET/MR imaging for disease screening were retrospectively reviewed and of them 114 with no clinical abnormality and no obvious lesions were enrolled in this study. The selected objects were grouped by ages from 20 to >70 years old every other 10 years. All the objects were scanned 6min/bed at ~30min or ~60min after tracer injection and data were reconstructed with OSEM (subset=28, iteration=3, pixel size=1.56mm, gaussian filter=3mm). The CortexID (GE Healthcare) was used to register the brain to the standard brain in Talairach space and extract the SUV in each cerebral cortex with a 26-region atlas. The SUV(mean) and SUV(mean) ratio of each cortex region relative to pons, cerebellum and global cerebral cortex average were plotted and compared. Results: The 18F-FDG uptakes and the SUV ratios in each age group for anterior cingulate right (R, ID = 7), anterior cingulate left (L, ID = 8), temporal lateral R (21), temporal lateral L (22), temporal mesial R (23), temporal mesial L (24) and pons (26) are relative lower than other regions while the primary visual R (19) and primary visual L (20) showed the greatest uptake in all the 26 regions. In compare with imaging at ~30min, the uptake pattern at ~60min seems more prominent and there are less variances of average uptake among groups. The absolute average SUV decreases with age except the 50~59years old group with unknown reason. Yet there are no significant differences (P>0.05) in the regions between adjacent groups, which may be caused by large SUV variance intragroup. For SUV ratios, the greatest variance among groups are demonstrated among averages of SUV ratio in regions relative to pons while the least variance showed for that of SUV ratios relative to global average. Less relative variances among groups and imaging time point were found for SUV ratios in compare with SUV. Significant differences (P<0.05) can be found between adjacent groups for SUV to pons ratio of temporal mesial, to global average ratio of prefrontal medial and primary visual at 30min, and SUV to pons ratio of sensorimotor and primary visual, prefrontal mesial, prefrontal lateral, parietal superior and parietal inferior, to cerebellum ratio of parietal superior and parietal inferior, and SUV to global average ratio of primary visual and parietal inferior at 60min. Conclusions: The 18F-FDG SUV uptake decreases with age, but the uptake patterns are similar with a more obvious contrast among cortex regions at 60min imaging time point. The SUV uptake ratios are more stable quantitative index than SUV absolute value especially the SUV ratio relative to global average value. Key Words:18F-FDG; normal uptake pattern; cerebral; PET/MR Fig. 1 SUV (A, B) and SUV ratio relative to pons (C, D), cerebellum (E, F) and global brain average uptake (G, H). SUV and SUV ration at ~30min (A, C, E, G) and ~60min(B, D, F, H) after tracer injection in various ages are plotted in each sub-figure. The cortex ID from 1 to 26 in represent respectively 1-Prefrontal Lateral R (right), 2-Prefrontal Lateral L(left), 3-Prefrontal Medial R, 4-Prefrontal Medial L, 5-Sensorimotor R, 6-Sensorimotor L, 7-Anterior Cingulate R, 8-Anterior Cingulate, 9-Posterior Cingulate R, 10-Posterior Cingulate L, 11-Precuneus R, 12-Precuneus L, 13-Parietal Superior R, 14-Parietal Superior L, 15-Parietal Inferior R, 16-Parietal Inferior L, 17-Occipital Lateral R, 18-Occipital Lateral L, 19-Primary Visual R, 20-Primary Visual L, 21-Temporal Lateral R, 22-Temporal Lateral L, 23-Temporal Mesial R, 24-Temporal Mesial L, 25-Cerebellum, 26-Pons.