[18F]Flutemetamol amyloid-beta PET imaging compared with [11C]PIB across the spectrum of Alzheimer's disease

Abstract

Purpose: The aim was to identify the amyloid beta (Aβ) deposition by positron emission tomography (PET) imaging with the (18)F-labeled Pittsburgh compound B (PIB) derivative [(18)F]flutemetamol (FMM) across a spectrum of Alzheimer's disease (AD) and to compare Aβ deposition between [(18)F]FMM and [(11)C]PIB PET imaging.

Methods: The study included 36 patients with AD, 68 subjects with mild cognitive impairment (MCI), 41 older healthy controls (HC) (aged ≥56), 11 young HC (aged ≤45), and 10 transitional HC (aged 46-55). All 166 subjects underwent 30-min static [(18)F]FMM PET 85 min after injection, 60-min dynamic [(11)C]PIB PET, and cognitive testing. [(18)F]FMM scans were assessed visually, and standardized uptake value ratios (SUVR) were defined quantitatively in regions of interest identified on coregistered MRI (cerebellar cortex as a reference region). The PIB distribution volume ratios (DVR) were determined in the same regions.

Results: Of 36 AD patients, 35 had positive scans, while 36 of 41 older HC subjects had negative scans. [(18)F]FMM scans had a sensitivity of 97.2% and specificity of 85.3% in distinguishing AD patients from older HC subjects, and a specificity of 100% for young and transitional HC subjects. The [(11)C]PIB scan had the same results. Interreader agreement was excellent (kappa score = 0.81). The cortical FMM SUVR in AD patients was significantly greater than in older HC subjects (1.76 ± 0.23 vs 1.30 ± 0.26, p < 0.01). Of the MCI patients, 68 had a bimodal distribution of SUVR, and 29 of them (42.6%) had positive scans. Cortical FMM SUVR values were strongly correlated with PIB DVR (r = 0.94, n = 145, p < 0.001).

Conclusion: [(18)F]FMM PET imaging detects Aβ deposition in patients along the continuum from normal cognitive status to dementia of AD and discriminates AD patients from HC subjects, similar to [(11)C]PIB PET.