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

Abstract

Purpose

The purpose of this study is to compare dynamic and static whole-body (WB) [¹⁸F]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 (V₀), 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.