Derivation and utility of an Aβ-PET pathology accumulation index to estimate Aβ load

Abstract

Objective: To evaluate a novel Aβ-PET based quantitative measure (Aβ accumulation index [Aβ-index]), including the assessment of its ability to discriminate between subjects based on Aβ-status using visual-read, CSF Aβ42/Aβ40 and post-mortem neuritic-plaque burden as standards of truth.

Methods: 1121 subjects (with and without cognitive impairment) scanned with Aβ-PET: Swedish BioFINDER, n=392, [18F]flutemetamol; ADNI, n=692, [18F]florbetapir; a phase-3 end-of-life study, n=100, [18F]flutemetamol). The relationships between Aβ-index and standardized uptake values ratios (SUVR) from Aβ-PET were assessed. The diagnostic performance of Aβ-index and SUVR were compared when using visual reads, CSF Aβ42/Aβ40 and Aβ-histopathology as reference standards.

Results: Strong associations were observed between Aβ-index and SUVR (R2, BioFINDER, 0.951; ADNI, 0.943, end-of-life, 0.916). Both measures performed equally well in differentiating Aβ-positive from Aβ-negative subjects, with...