Comparison Between ¹⁸F-Florapronol and ¹⁸F-Florbetaben Imaging in Patients With Cognitive Impairment

Background and purpose: To determine the imaging characteristics and cutoff value of ¹⁸F-florapronol (FC119S) quantitative analysis for detecting β-amyloid positivity and Alzheimer's disease (AD), we compared the findings of FC119S and ¹⁸F-florbetaben (FBB) positron-emission tomography (PET) in patients with cognitive impairment.

Methods: We prospectively enrolled 35 patients with cognitive impairment who underwent FBB-PET, FC119S-PET, and brain magnetic resonance imaging. We measured global and vertex-wise standardized uptake value ratios (SUVRs) using a surface-based method with the cerebellar gray matter as reference. Optimal global FC119S SUVR cutoffs were determined using receiver operating characteristic curves for β-amyloid positivity based on the global FBB SUVR of 1.478 and presence of AD, respectively. We evaluated the global and vertex-wise SUVR correlations between the two tracers. In addition, we performed correlation analysis for global or vertex-wise SUVR of each tracer with the vertex-wise cortical thicknesses.

Results: The optimal global FC119S SUVR cutoff value was 1.385 both for detecting β-amyloid positivity and for detecting AD. Based on the global SUVR cutoff value of each tracer, 32 (91.4%) patients had concordant β-amyloid positivity. The SUVRs of FC119S and FBB had strong global (r=0.72) and vertex-wise (r>0.7) correlations in the overall cortices, except for the parietal and temporal cortices (0.4<r<0.7). The FC119S SUVR had significant negative vertex-wise correlations with cortical thicknesses in the posterior cingulate, anterior cingulate, parietal, posterior temporal, and occipital cortices.

Conclusions: Quantitative FC119S-PET analysis provided reliable information for detecting β-amyloid deposition and the presence of AD.