RESUMEN
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 (Ki) from Patlak analyses correlated well with nonlinear regression analysis, but Ki results using Patlak analysis were lower than Ki results using nonlinear regression analysis. However, no significant difference was found between Ki obtained by static WB scans and Ki 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 Ki in patients with CKD-MBD, but the results should not be compared uncritically with results obtained by dynamic scan analysis.
RESUMEN
The modified International Knee Documentation Committee Subjective Knee Form (Pedi-IKDC) is a widely used patient-reported tool ranging on a scale from 0 to 100. We aimed to translate Pedi-IKDC into Danish and assess its reproducibility and responsiveness in children with knee disorders. The translation complied with the international guidelines. Reproducibility was assessed in 53 children (15 years) responding Pedi-IKDC at baseline and after 3-14 days. For analysis of responsiveness, 94 children (15 years) responded Pedi-IKDC again after 3 months. Test-retest reliability was excellent. Intraclass correlation coefficient was 0.9, standard error of measurement was 4.1 points, and smallest detectable change (SDC) was 11.3 points. Evaluating responsiveness as a large effect was found in children reporting improvement compared with children reporting deterioration. The change score was correlated to the external anchor Global Rating Scale consisting of 15 answers from -7 "A very great deal worse" to +7 "A very great deal better," with a Spearmen's rho of 0.45 (P > 0.001). The minimal clinically important changes was 12.0. In conclusion, excellent test-retest reproducibility was found at group level, but at individual level the SDC was high. The Pedi-IKDC showed adequate responsiveness and is suitable for assessing improvement or deterioration in children with knee disorders.
