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.

Keywords: Pittsburgh compound B; cognitive impairment; fluorodeoxyglucose; memory clinic; positron emission tomography.