Application of [¹⁸F]NaF and [¹⁸F]FDG PET/CT to Assess Molecular Calcification and Glucose Metabolism in Thyroid Cartilage

Objective: Thyroid cartilage calcification and glucose metabolism may vary with age and gender. This study aimed to investigate the role of [18F]-sodium fluoride ([18F]NaF) and 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) PET/CT for the evaluation of physiological molecular calcification and glucose metabolism of thyroid cartilage with age. Methods: This retrospective study analyzed [18F]NaF and [¹⁸F]FDG PET/CT images from the CAMONA study (NCT01724749). Regions of interest were placed around the thyroid cartilage on CT images using OsiriX software. The mean standardized uptake value (SUVmean) was measured for [¹⁸F]NaF and [¹⁸F]FDG PET/CT images. Pearson correlation coefficients were calculated to evaluate the effects of aging on the uptake of [¹⁸F]NaF and ^[18F]FDG in the thyroid cartilage. Results: A total of 127 healthy subjects (65 females and 62 males) with a mean age of 48.46±14.13 (range 21–75) years for [¹⁸F]NaF PET/CT and a total of 114 healthy subjects (52 females and 63 males) with a mean age of 49.05±14.29 (range 21–75) years for [¹⁸F]FDG PET/CT were included. A significant positive correlation was observed between age and SUVmean of [¹⁸F]NaF in the thyroid cartilage (r=0.18, p=0.04). This result indicates that molecular calcification of this cartilage increases with aging. However, the correlation between age and SUVmean of [¹⁸F]FDG in the thyroid cartilage was not statistically significant (r=-0.09 p=0.31). Conclusion: This study presents a novel methodology for the determination of molecular calcification and glucose metabolism of laryngeal cartilage using [¹⁸F]NaF and [¹⁸F]FDG PET/CT. Molecular calcification of thyroid cartilage was found to increase with age, whereas glucose metabolism did not show a statistically significant correlation with age.