Abstract:

[Abstract] Objective   To investigate the value of N-[11C] methyl-2 - methylamino-phenyl-6 - hydroxy - benzo-thiazole (11C-PIB) and 18F-deoxyglucose (FDG) positron emission tomography (PET) in the differential diagnosis of Al-zheimer's disease (AD) and frontotemporal dementia (FTD). Methods   Ten patients who were difficult to diagnose for AD and FTD underwent 11C-PIB and 18F-FDG PET combined brain imaging. Eighteen age-matched healthy elderly controls un-derwent 18F-FDG PET. SPM8 software was used for FDG scan image data analysis. The 2-sample t-test was used in the study and P < 0.001 was considered statistically significant. The 55~60 min PIB scans were classified as positive or negative by visual analysis. PIB scans were rated as“PIB-positive”if tracer binding was deemed greater in cortical gray matter than in white matter, and as“PIB-negative”if only nonspecific white matter binding was observed. Results   After undergoing amy-loid and FDG PET scans, 5 typical AD images were distinguished. FDG imaging pattern presented as focal cortical hypome tabolism in bilateral parietotemporal association cortexes and the posterior cingulated gyrus, the precuneus. PIB was positive. There were two typical FTD images, showing the significant regional reductions in rCMRglc in bilateral frontal, the cingualte gyri, insulae and the subcortical structures. PIB was negative. Three patients, who underwent 18F-FDG brain imaging, were still difficult to identify. 11C-PIB brain imaging prompted 2 AD patients and 1 FTD patient, which were confirmed after 5 to 6-month follow-up. Conclusion   PIB and FDG PET could provide dual functional information in the differential diagnosis of AD and FTD, especially the lower specificity in rCMRglc in some cases, PIB imaging was helpful.

Key words: Alzheimer's disease, amyloid, positron-emission tomography, Fluorodeoxyglucose F18, diagnosis, differential, frontotemporal lobar degeneration