Background: 18F-FDG-PET is defined as a biomarker of neuronal injury according to the revised National Institute on Aging-Alzheimer's Association criteria. Objective: The objective of this multicenter prospective cohort study was to examine the value of 18F-FDG-PET in predicting the development of Alzheimer's disease (AD) in patients with mild cognitive impairment (MCI). Methods: In total, 114 patients with MCI at 9 participating institutions underwent clinical and neuropsychological examinations, MRI, and 18F-FDG-PET at baseline. The cases were visually classified into predefined dementia patterns by three experts. An automated analysis for 18F-FDG-PET was also performed to calculate the PET score. Subjects were followed periodically for 3 years, and progression to dementia was evaluated. Results: In 47% of the patients with MCI, progression of symptoms justified the clinical diagnosis of «probable AD». The PET visual interpretation predicted conversion to AD during 3-year follow-up with an overall diagnostic accuracy of 68%. Overall diagnostic accuracy of the PET score was better than that of PET visual interpretation at all follow-up intervals, and the optimized PET score threshold revealed the best performance at the 2-year follow-up interval with an overall diagnostic accuracy of 83%, a sensitivity of 70%, and a specificity of 90%. Multivariate logistic regression analysis identified the PET score as the most significant predictive factor distinguishing AD converters from non-converters. Conclusion: The PET score is the most statistically significant predictive factor for conversion from MCI to AD, and the diagnostic performance of the PET score is more promising for rapid converters over 2 years.
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