The value of FDG combined with PiB PET in the diagnosis of patients with cognitive impairment in a memory clinic

Abstract Aims To analyze the value of 18 F‐fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with amyloid PET in cognitive impairment diagnosis. Methods A total of 187 patients with dementia or mild cognitive impairment (MCI) who underwent 11 C‐Pittsburgh compound B (PiB) and FDG PET scans in a memory clinic were included in the final analysis. Results Amyloid‐positive and amyloid‐negative dementia patient groups showed a significant difference in the proportion of individuals presenting temporoparietal cortex ( p < 0.001) and posterior cingulate/precuneus cortex ( p < 0.001) hypometabolism. The sensitivity and specificity of this hypometabolic pattern for identifying amyloid pathology were 72.61% and 77.97%, respectively, in patients clinically diagnosed with AD and 60.87% and 76.19%, respectively, in patients with MCI. The initial diagnosis was changed in 32.17% of patients with dementia after considering both PiB and FDG results. There was a significant difference in both the proportion of patients showing the hypometabolic pattern and PiB positivity between dementia conversion patients and patients with a stable diagnosis of MCI ( p < 0.05). Conclusion Temporoparietal and posterior cingulate/precuneus cortex hypometabolism on FDG PET suggested amyloid pathology in patients with cognitive impairment and is helpful in diagnostic decision‐making and predicting AD dementia conversion from MCI, particularly when combined with amyloid PET.