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CONVERSION TO AMYLOID POSITIVITY: PREDICTIVE VALUE OF GLOBAL AND REGIONAL CENTILOID QUANTIFICATION
Abstract
Aims
Identification of early amyloid pathology can be of value for preventive trials. We assessed whether global and regional Centiloid (CL) predicted conversion to amyloid-positivity based on PET visual read (VR) in a cognitively unimpaired (CU) population.
Methods
Longitudinal [18F]flutemetamol amyloid-PET scans were performed on a Philips PET-MRI system in 140 CU participants from the EMIF-AD Twin60++ study (Table 1), with an average follow-up (FU) time of 4.34y (3.7–6.2). All scans were visually assessed as negative or positive (VR-/VR+) and subjects were classified as Stable VR-, Converter or Stable VR+. Global and regional quantitative values were obtained using the CL method. Generalized Estimating Equation (GEE) was used to assess differences between VR-groups in global and regional CL baseline burden and yearly rate of change (ΔCL). Analyses were corrected for age, sex, and, APOE-ε4 carriership.
Results
At baseline, 14.3% of subjects were considered VR+ and displayed higher CL burden compared to VR- cases (β=39.6, p<.001). At FU, 17 (14.2%) subjects converted to VR+. Converters did not have higher baseline global CL burden, but did show a higher global ΔCL compared to stable VR- cases (β=3.3, p<.001), Figure 1A). In contrast, the PC/PCC ROI of converters had both a higher baseline CL (β=20.9, p<0.001 ) and ΔCL compared to Stable VR- subjects (β=5.0, p<.001, Figure 1B, Table 2).
Conclusions
Baseline regional CL quantification in the PC/PCC, rather than global, could predict conversion to amyloid-positivity based on visual assessment in a CU population. This could support selection of participants for future primary prevention trials.