Abstract: Objective Amyloid imaging clinically is usually reported as
positive or negative, and the role of amyloid topography has
not been studied before. To evaluate in a clinical setting the
regional distribution patterns of 11C-Pittsburgh compound B
(11C-PIB) and the fluorine-18-fluorodeoxyglucose
(18F-FDG) uptake in patients with mild cognitive impairment
(MCI), we designed this study.
Methods We studied 81 consecutive MCI patients, 64
amnestic (A-MCI) and 17 nonamnestic (NA-MCI) by 11C-PIB
and 18F-FDG PET/computed tomography, by visual
analysis. PIB retention was classified according to the
regional distribution into the following patterns: A (frontal,
lateral temporal, basal ganglia and anterior cingulate) and B
(global retention). 18F-FDG images were considered
positive only if temporoparietal hypometabolism consistent
with Alzheimer’s disease was observed.
Results In 42 of the 64 A-MCI, 11C-PIB was positive. Twelve
of the 42 positive A-MCI showed an A-pattern, all 18F-FDG
negative, and 30 a B-pattern, 10 18F-FDG positive and 20
18F-FDG negative. Of the 17 NA-MCI, 11C-PIB was positive
in three and 18F-FDG was positive in one. The different
proportion of 11C-PIB positivity in A-MCI and NA-MCI was
highly significant (P<0.001).
Conclusion Two different 11C-PIB patterns were observed
in MCI patients and for the A-pattern, glucose
hypometabolism consistent with Alzheimer’s disease is
highly unlikely. These findings may contribute towards a
better selection of patients for future potential treatments
and also to optimize the use of 18F-FDG-PET/CT.
