Impact of (18)FDG PET and (11)C-PIB PET brain imaging on the diagnosis of Alzheimer's disease and other dementias in a regional memory clinic in Hong Kong.

OBJECTIVE: This study investigated the improvement in the accuracy of diagnosis of dementia subtypes among Chinese dementia patients who underwent [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography ((18)FDG PET) with or without carbon 11-labelled Pittsburgh compound B ((11)C-PIB).

METHODS: This case series was performed in the Memory Clinic at Queen Mary Hospital, Hong Kong. We reviewed 109 subjects (56.9% were female) who received PET with or without (11)C-PIB between January 2007 and December 2014. Data including age, sex, education level, Mini-Mental State Examination score, Clinical Dementia Rating scale score, neuroimaging report, and pre-/post-imaging clinical diagnoses were collected from medical records. The agreement between the initial and post-PET with or without (11)C-PIB dementia diagnosis was analysed by the Cohen's kappa statistics.

RESULTS: The overall accuracy of initial clinical diagnosis of dementia subtype was 63.7%, and diagnosis was subsequently changed in 36.3% of subjects following PET with or without (11)C-PIB. The rate of accurate initial clinical diagnosis (compared with the final post-imaging diagnosis) was 81.5%, 44.4%, 14.3%, 28.6%, 55.6% and 0% for Alzheimer's disease, dementia with Lewy bodies, frontotemporal dementia, vascular dementia, other dementia, and mixed dementia, respectively. The agreement between the initial and final post-imaging dementia subtype diagnosis was only fair, with a Cohen's kappa of 0.25 (95% confidence interval, 0.05-0.45). For the 21 subjects who underwent (11)C-PIB PET imaging, 19% (n=4) of those with Alzheimer's disease (PIB positive) were initially diagnosed with non-Alzheimer's disease dementia.

CONCLUSIONS: In this study, PET with or without (11)C-PIB brain imaging helped improve the accuracy of diagnosis of dementia subtype in 36% of our patients with underlying Alzheimer's disease, dementia with Lewy bodies, vascular dementia, and frontotemporal dementia.