. 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;

Abstract:

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 region.

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.

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  1. Toronto: HAI Amyloid Imaging Conference Abstracts