Evaluation of Bone Metabolic Activity in the Spine with 18 F-FDG and 18 F-NaF PET/CT Imaging: Associations with Degenerative Risk Factors

Purpose: Imaging vertebral molecular activity with positron emission tomography (PET)/computed tomography (CT) may enable earlier detection of degenerative diseases of the spine. This study aimed to evaluate patterns of vertebral molecular activity and their association with degeneration with ¹⁸ F-fluorodeoxyglucose ( ¹⁸ F-FDG) and ¹⁸ F-sodium fluoride ( ¹⁸ F-NaF) PET/CT. Methods: 120 subjects (mean age 48.8 ± 14.1 years, 51% male) underwent ¹⁸ F-FDG and ¹⁸ F-NaF PET/CT imaging. The TotalSegmentator software was used to automatically generate regions of interest (ROIs) surrounding each vertebral body (VB) to quantify mean standardized uptake value (SUVmean) for each radiotracer, average Hounsfield Units (HU), and volume. Results: Cervical and lumbar ¹⁸ F-FDG SUVmean exceeded thoracic uptake (p < 0.01). ¹⁸ F-NaF activity was greatest in the lumbar spine, followed by the thoracic and the cervical regions (p < 0.01). ¹⁸ F-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). ¹⁸ F-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 ¹⁸ F-FDG ^{and 18 F-NaF SUVmean were higher in females than males. Conclusion: 18 F-FDG and 18 F-NaF PET/CT reveal molecular alterations in the spine associated with degenerative risk factors, which may improve screening and prognostic methods for vertebral pathology.}