Vandenberghe R, Van Laere K, Ivanoiu A, Salmon E, Triau E, Hasselbalch S, Law I, Andersen A, Korner A, Brooks DJ.
Primary outcome analysis of the multicentre phase II trial of 18F-flutemetamol, a Pittsburgh Compound B derivative for in vivo beta amyloid imaging.
Human Amyloid Imaging 2010 Meeting Abstracts. 2010 April 9;
Objective: 1. Primary: To determine the efficacy of visual assessment of 18F-flutemetamol scans in assigning
patients with clinically probable Alzheimer’s disease (AD) and cognitively intact healthy volunteers (HV) to a 'raised'
versus 'normal' uptake category, with the clinical diagnosis as standard of truth (SOT). 2. To compare visual
assignment of 18F-flutemetamol scans in AD and amnestic mild cognitive impairment (MCI) with visual assignment
based on 11C-PIB scans. 3. To compare the visual reads with categorization based on quantitative measures.
Methods: 27 patients with early-stage AD, 20 with MCI, 15 HV above and 10 HV below 55 years, underwent an
18F-flutemetamol PET scan (max target activity 185 MBq, acquisition window 85-115 min post-injection). 20 of
the AD and 20 of the MCI cases also underwent a 11C-PIB PET (max target activity 370 MBq, acquisition window
40-70 min post-injection). Five independent readers assigned the 18F-flutemetamol scans to either ‘raised’ or
‘normal’ uptake category in a binary way. Inter-rater agreement was expressed by Fleis’ kappa coefficient. In
a separate session 3 months later, the same readers classified the 40 11C-PIB scans. Quantitative analysis was
based on Standardized Uptake Value Ratios (SUVR) in a composite cortical region with cerebellum as reference
Results: 25/27 18F-flutemetamol scans from the AD subjects and 1 scan from the 15 elderly HVs were visually
assigned to the raised uptake category (sensitivity and specificity of 93.1% and 93.3%, respectively). Nine MCI
cases were assigned to the raised uptake category. Across all groups, kappa was 0.96. Visual assignment based
on 18F-flutemetamol strictly matched that based on 11C-PIB. In AD and HV, visual and SUVR-based classifications
were strictly concordant. In 2 MCI subjects, SUVR values were just above threshold while they were read as
negative by all 5 readers.
Conclusion: This phase II study met its primary objective.