The Efficacy of 18F-Flutemetamol in Discrimination of Cognitive Impairment and Dementia by PET-CT

Abstract

Background: Amyloid imaging with newly developed tracer 18F‐flutemetamol has high sensitivity to detect Ab deposition and is characteristic as a noninvasive method. The objective of our study was to discriminate cognitive impairment and different types of dementia including subjective cognitive decline (SCD), Alzheimer's disease (AD), vascular dementia (VaD) and mixed dementia (MIX) through 18F‐flutemetamol and PET‐CT scan. Methods: Fifty‐two subjects with dementia or cognitive impairment were recruited with similar age and gender. The final diagnosis (gold standard) was made by a panel consisting of 1 neuroradiologist and 2 neurogeriatricians based on clinical, neuropsychological testing, MRI and Flutametamol PET‐CT findings, which included 9 SCD subjects, 19 AD/aMCI subjects, 16 VaD/VCI subjects and 8 MIX subjects Standardized uptake value ratios (SUVR) using the pons as a reference region were calculated between 90 and 110 min after injection. Results: There was no significant difference among four groups in age, sex and education. Using global binding SUVR, AD group had significantly higher composite SUVR than VaD (p<0.0001) and SCD group (p<0.001), while MIX group had significantly higher SUVR than VaD group (p<0.001). Considering the specific regions of interest, there were 16 out of 16 regions presented with significant differences between AD and VaD; and 12 regions indicated significant differences between SCD and AD. VaD could be differentiated from MIX group by 10 regions. In particular, right Prefrontal cortical region could be considered as a most typical region for discrimination of AD from SCD/VaD, and VaD from MIX. The specific cutoff values of prefrontal R were calculated by Youden index in three pairwise comparisons. There was inverse correlation between Montreal Cognitive Assessment (MoCA) and global binding of Ab among the entire cohort (p<0.05). Conclusions: 18F‐flutemetamol PET‐CT had high sensitivity to discriminate AD from VaD, AD from SCD and VaD from MIX based on the global Ab burden and specific regional binding. The cutoff values of prefrontal R can be used for discrimination further. The results of Ab binding using 18F‐flutemetamol are comparable for those using 11C‐PiB or 11F‐florbetaben as a tracer.