P4‐056: Mild cognitive impairment: Differential atrophy in the hippocampal subfields

gional [C]PIB R1 values strongly correlate with normalized regional [F]FDG uptake (R 1⁄4 0.62 across all regions and subjects; R 1⁄4 0.73 6 0.11 across regions within subjects). A regression model including [F]FDG uptake,subject and region grouping (cortical, subcortical and limbic to allow for possible differences in flow/metabolism coupling), accounts for 86% of total [C]PIB R1 variability. Aß-load ([ 11C]PIBBPND) exhibited no significant effect on the association between [C]PIB R1 and [F]FDGuptake. Voxel-based correlation analyses with MMSE reveal very similar corefindings of positive correlation in the posterior cingulate gyrus/precuneus and negative correlations (preserved activity) in bilateral sensorimotor cortex. There was no correlation between Aß-load (BPND) and MMSE. Conclusions: These results strongly suggest that [C]PIB R1 can serve as a complementary biomarker of neuronal activity and, thus, neuronal dysfunction in addition to Aß-load given by [11C]PIBBPND. Further studies need to validate the diagnostic value of dual biomarker [C]PIBPET studies in comparison to combined [F]FDG and [C] PIB PET studies. Compared to the latter, dual biomarker [C]PIB PET imaging greatly reduces costs and burden to the patients.