Evaluation of physiological bone metabolic activity in the spine with 18F-fluorodeoxyglucose and 18F-sodium fluoride PET: associations with degenerative risk factors

OBJECTIVE: Imaging vertebral molecular activity with PET/computed tomography (CT) may enable earlier detection of degenerative diseases of the spine. This study aimed to evaluate physiological patterns of vertebral molecular activity and their association with degenerative risk factors with 18F-fluorodeoxyglucose (18F-FDG) and 18F-sodium fluoride (18F-NaF) PET/CT. METHODS: 120 subjects (mean age 48.8 ± 14.1 years, 51% male) underwent 18F-FDG and 18F-NaF PET/CT imaging. The TotalSegmentator software was used to automatically generate regions of interest surrounding each vertebral body to quantify mean standardized uptake value (SUVmean) for each radiotracer, average Hounsfield Units, and volume. RESULTS: Cervical and lumbar 18F-FDG SUVmean exceeded thoracic uptake (P < 0.01). 18F-NaF activity was greatest in the lumbar spine, followed by the thoracic and the cervical regions (P < 0.01). 18F-FDG SUVmean was associated with age (ρ = 0.19, P = 0.03, cervical), BMI (ρ = 0.28-0.40, P < 0.01, all regions), bone density (ρ = -0.30, P = 0.01, cervical), and volume (ρ = -0.20, P = 0.02, cervical). 18F-NaF SUVmean correlated with age (ρ = 0.21 and -0.20, P ≤ 0.03 in cervical and lumbar regions, respectively), BMI (ρ = 0.23 and 0.26, P ≤ 0.01in thoracic and lumbar regions, respectively), bone density (ρ = 0.38, P < 0.01, lumbar), and volume (ρ = -0.30, P < 0.01, lumbar). Cervical 18F-FDG and 18F-NaF SUVmean were higher in females than males. CONCLUSION: 18F-FDG and 18F-NaF PET/CT reveal distinct physiological patterns of vertebral molecular activity associated with degenerative risk factors, which may improve screening and prognostic methods for vertebral pathology.