The association of 11C-PIB uptake and cerebral glucose metabolism on 18F-FDG PET in Alzheimer's disease

Objectives The aim of this study was to evaluate the association between beta-amyloid deposits measured by ¹¹C-PIB PET and cerebral glucose metabolism measured by ¹⁸F-FDG PET.

Methods 23 patients with Alzheimer’s disease, 20 with mild cognitive impairment and 24 normal elderly underwent 90-min dynamic PIB PET and static FDG PET. First, z transformations of all images were performed with respect to normal average and SD, and the association of the number and mean z-value of abnormal voxels between corresponding images was evaluated. Further, the correlation of regional PIB uptake and glucose metabolism was evaluated in the entire brain.

Results The number of abnormal voxels (r=0.71,p<0.0001) across the entire brain and the mean z-values of abnormal voxles (r=0.53,p<0.0001) between corresponding PIB and FDG PET were significantly associated (z threshold of 2.97 for PIB, -2.97 for FDG). In SPM analysis, the regional PIB uptake in the frontal, parietal,temporal and precuneus cortices was negatively correlated with the metabolism in bilateral parietal, mesial temporal cortices and posterior cingulate gyrus on FDG PET. The regional metabolism on FDG PET in parietal, temporal and precuneus cortices was correlated with PIB uptake in right frontal cortex.

Conclusions This data demonstrated that extent and severity of amyloid deposits was correlated with those of metabolic abnormality in the entire brain, and regional patterns of correlation may reflect the distribution of pathologic and metabolic abnormalities in disease progression.