Correlation between brain glucose metabolism (18F-FDG) and cerebral blood flow with amyloid tracers (18F-Florbetapir) in clinical routine: Preliminary evidences

Abstract

Objective: This study compared the performance of ¹⁸F-Florbetapir PET/CT early acquisitions to ¹⁸F-FDG PET/CT.

Methods: We included 12 patients who underwent ¹⁸F-FDG PET/CT and a dual-time ¹⁸F-Florbetapir PET/CT (1-6 min early-scan and 50 min late-scan). PET/CT were analyzed visually by three nuclear medicine physicians with different experience using a four-point scale (0 = no reduction, 1 = slight, 2 = moderate, 3 = severe reduction) for ¹⁸F-Florbetapir early-phase and ¹⁸F-FDG images in 10 cortical regions (bilateral frontal, temporal, parietal, occipital, posterior cingulate/precuneus), and ¹⁸F-Florbetapir late-phase in the same cortical regions using a three-point scale (0 = normal, 1 = abnormal with minor plaques, 2 = abnormal with major plaques). We used SPM12 for semiquantitative analysis applying a ROI-based correlation analysis (considering precuneus as target region and normalized for the mean global binding), a covariance-analysis taking precuneus as target and a comparison of global DMN (default mode network).

Results: Inter-reader agreement was high (Cohen's kappa 0.762 for ¹⁸F-FDG, 0.775 for ¹⁸F-Florbetapir early-phase and 0.794 for late-phase). Regional visual scores of early-phase and ¹⁸F-FDG were significantly correlated (ρ = 0.867). Also ROI-based analysis, global brain visual analysis and DMN comparison revealed concordant results, especially at parietal and precuneus (p < 0.001).

Conclusions: ¹⁸F-Florbetapir early-phase scans significantly correlate on quantitative and visual images with ¹⁸F-FDG-PET/CT scans, suggesting that amyloid tracer could be instead of ¹⁸F-FDG.

Keywords: (18)F-FDG; (18)F-Florbetapir; Amiloide; Amyloid; Dual-phase; Fase dual; PET.