Evaluation of Visible Physiological F-18 FDG Uptake Patterns in Spinal Cord on PET/CT

Abstract

Background: The accurate interpretation of 18-F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) images requires knowledge of the normal patterns, intensities, and frequencies of FDG distribution in the whole body. Aims: In this study, we aimed to evaluate distribution patterns, frequencies, and intensities of visible physiological FDG cord uptake in patients with no known abnormality in this region on PET/CT. Methods: A total of 113 patients (71 men, 42 women; mean age 57.2±14.2 y; range 24 to 88 y) who had been investigated by FDG PET/CT were studied retrospectively. For each scan, spinal cord was visually assessed for FDG uptake, and its intensity was semiquantitatively graded on a 3-point scale as grade 0 (no visible uptake), grade 1 (mild uptake), or grade 2 (moderate uptake). Results: Mild or moderate FDG cord uptake was observed in 82 patients (82/113; 72.6%). In most of the cases uptake was observed in all cervical (72/113; 63.7%), thoracic 11-12 (66/113; 58.4%), and lumbar 1 (24/113; 21.2%) vertebral levels of the cord. Conclusions: Visible mild FDG uptake in the spinal cord is a common finding in PET/CT imaging. No significant association with age or sex was observed. Such physiological uptake can appear mostly at the cervical and T11-L1 vertebral levels. At these levels, moderate uptake is also frequently encountered. However, in the upper thoracic regions, only mild uptake is observed.