Comparison of [18F] NaF PET/CT dynamic analysis methods and a static analysis method including derivation of a semi-population input function for site-specific measurements of bone formation in a population with chronic kidney disease-mineral and bone disorder

PURPOSE: The purpose of this study is to compare dynamic and static whole-body (WB) [(18)F]NaF PET/CT scan methods used for analysis of bone plasma clearance in patients with chronic kidney disease-mineral and bone disorder (CKD-MBD). METHODS: Seventeen patients with CKD-MBD underwent a 60-min dynamic scan followed by a 30-min static WB scan. Tracer kinetics in four thoracic vertebrae were analysed using nonlinear regression and Patlak analysis using image-derived arterial input functions. The static WB scan was analysed using a simplified Patlak method requiring only a single data point in combination with a fixed y-intercept value (V(0)), both obtained using a semi-population function. The semi-population function was constructed by combining a previously derived population input function in combination with data from venous blood samples. Static WB scan analysis data, obtained from the semi-population input functions, was compared with paired data obtained using dynamic input functions. RESULTS: Bone plasma clearance (K(i)) from Patlak analyses correlated well with nonlinear regression analysis, but K(i) results using Patlak analysis were lower than K(i) results using nonlinear regression analysis. However, no significant difference was found between K(i) obtained by static WB scans and K(i) obtained by dynamic scans using nonlinear regression analysis (p = 0.29). CONCLUSION: Bone plasma clearance measured from static WB scans correlates with clearance data measured by dynamic analysis. Static [18F]NaF PET/CT scans can be applied in future studies to measure K(i) in patients with CKD-MBD, but the results should not be compared uncritically with results obtained by dynamic scan analysis.