Centiloid scale evaluation for β‐amyloid PET of cognitively normal elderly and SuperAgers

Abstract

AbstractBackgroundThe Centiloid scale (CL) represents an attempt to standardize amyloid imaging to create a measure of global cortical β‐amyloid deposition using positron emission tomography (PET). The CL approach transforms standard uptake value ratio (SUVR) into values ranging from 0 to 100. This study aims to investigate the brain amyloid load in SuperAgers (SA), healthy age‐matched controls (ACs), and healthy middle‐aged controls (MCs).MethodThirty cognitively healthy individuals were evaluated with a cognitive screening and the Rey Auditory‐Verbal Learning Test (A7 list). They underwent an amyloid PET image with PIB were acquired in 3D mode from 40 to 60 minutes after injection using a PET/CT scanner (Discovery 600, GE Healthcare). Image analysis was performed using the PMOD software ‐ PNEURO tool (PMOD Technologies). SUVR was transformed to CTX (Global Cortical Target region) using the whole cerebellum (WC) as reference. The equation used to convert SUVR to CL is CL=100 (SUVR‐0.987)/1.019 and fits the parameters described previously.ResultTotal sample included 10 MCs (58.7±5.52 years‐old; A7 = 10.7±3.4), 10 ACs (83.5±4.2 years‐old; A7 = 6.9±1.7) and 10 SA (83.3±2.63 years‐old; A7 = 11.4±2.01). No significant difference was observed in the group analysis between amyloid SUVR between MC, SA, and AC groups (p=0.084). However, the mean CL values were for MCs: 0.65±6.5 CL; ACs: 31.20±34.5 CL; SA: 21.2±33.7 CL. The SuperAgers group exhibited a similar amyloid‐β burden compared with AC, even though A7‐RAVLT test results were significantly different (p=0.001).ConclusionThe CL approach was successfully implemented in various cognitive aging trajectories using the [11C]PiB PET. SuperAgers exhibited a similar amyloid‐β load to that of age‐matched healthy controls in both SUVR and CL analyses. Tau studies could help to find a better relationship between biomarker load and cognitive behavior.