Long-term Changes in 18F-Flutemetamol Uptake in Nondemented Older Adults.

Purpose: Longitudinal studies into the variability of F-18-Flutemetamol uptake are lacking. Methods/Patients: Therefore, the current study examined change in F-18-Flutemetamol uptake in 19 nondemented older adults (65 to 82 y old) who were either cognitively intact or had Mild Cognitive Impairment (MCI) who were scanned twice across 3.6 years. Results: Baseline and follow-up composite SUVRs were significantly correlated (0.96, P<0.001). Significant increases in the composite SUVR from baseline to follow-up were observed (P=0.002). For the total sample, the average difference over this time period when using the composite SUVR was 6.8%. Similar results were seen in subsets of the total sample (MCI vs. cognitively intact, amyloid positive vs. negative). Finally, a Reliable Change Index that exceeded +/- 0.046 SUVR units would indicate a significant change of F-18-Flutemetamol. Conclusions: The current results extend the limited literature on longitudinal variability of F-18-Flutemetamol uptake across 3.6 years, which should give clinicians and researchers more confidence in the stability of this amyloid imaging agent in longer therapeutic and prevention trials in cognitive decline in MCI and Alzheimer disease.