Additional role of 18F-NaF PET/CT for assessment of bone mineral density change in DTC patients with TSH suppression

Objective To explore the additional functionalities of 18 F-sodium fluoride-positron emission tomography/computed tomography ( 18 F-NaF PET/CT) for evaluation and prediction of bone mineral density (BMD) levels in differentiated thyroid cancer (DTC) under thyrotropin suppression. Methods This study analyzed retrospectively 231 DTC patients who was receiving thyrotropin suppression, and received dual emission X-ray absorptiometry (DXA) and 18 F-NaF PET/CT scans within one week. According to the BMD of DXA, they were divided into normal, osteopenia, and osteoporosis group, as well as the incidence of each group was recorded. The 18 F-NaF uptake value of 1st-4th lumbar vertebrae and femoral neck of each patient was measured and compared based on the different BMD, gender and duration of TSH suppression by one-way ANOVA or Mann Whitney U test. The correlation was calculated between age and 18 F-NaF uptake value and BMD of the lumbar spine by Pearson or Spearman regression analysis. In addition, using the receiver operating characteristic (ROC) curves established a model to predict the BMD level based on the 18 F-NaF uptake value. Results The incidence rate of osteopenia and osteoporosis was 30.3% and 11.6%, and postmenopausal women are the most susceptible group to osteopenia (37%) and osteoporosis (29%). The SUV max , SUV mean of the lumbar spine were statistically significantly different among the normal, osteopenia, and osteoporosis groups (all p < 0.05), but no significant difference was observed in 18 F-NaF uptake of femoral neck. Additionally, SUV max , SUV mean of the lumbar spine were also observed significant difference among different gender (all p < 0.05) and duration of TSH suppression (all p < 0.05). Lumbar SUV max , SUV mean , and BMD were significantly negatively correlated with age (r = − 0.426 to − 0.511, all p < 0.05). The C-index of the combined model was 0.70(95% CI 0.64–0.76), suggesting reasonably good model performance for distinguishing normal to abnormal BMD. Conclusion 18 F-NaF PET/CT can be a valuable adjunct to DXA to provide insight into bone metabolism in DTC patients with TSH suppression, apart from detection of metastatic bones.