%0 Journal Article %A Teng Xie %A Xiaojun Zhang %A Luning Wang %A Hengge Xie %A Jinming Zhang %A Baixuan Xu %A Huali Wang %A Liping Fu %T Relationships between tau, atrophy, regional brain activity and connectivity in Alzheimer's disease: a PET/MRI multimodal study %D 2020 %J Journal of Nuclear Medicine %P 599-599 %V 61 %N supplement 1 %X 599Objectives: To investigate the multimodal neuroimaging relationship between Tau, structural and functional brain parameters in healthy elders (HEs) and patients with Alzheimer’s Disease (AD). Methods: 29 AD and 17 HE subjects enrolled in the study. All subjects received 18F-THK5317 injection intravenously (4.44-5.55MBq/kg) 40-min prior to data acquisition at a PET/MRI scanner (Biograph mMR, SIEMENS, Germany). The PET data were acquired with the duration of 20 minutes and the MRI scanning was performed simultaneously with PET imaging with the following sequence protocol: Sagital 3D T1WI magnetization prepared rapid gradient echo (MPRAGE); transverse T2-FLAIR and BOLD-ep2d-RESTING STATE. All subjects had THK5317-PET and T1 MRI scanning, in which 22 AD and 12 HE subjects had resting-state BOLD data. T1 images were segmented and normalized to MNI space using CAT12 toolbox with DARTEL normalization. The fMRI images and PET images were coregistered to T1 images and normalized using deformation fields derived from structural analysis. Other preprocessing procedures were conducted using SPM12. 3 AD and 1 HE were excluded from fMRI analysis because of large head motion. We calculated PET SUVR, gray matter volume (GMV), amplitude of low frequency fluctuations (ALFF), fractional ALFF (fALFF) and functional connectivity strength (FCS). We compared each parameter between the 2 groups and investigated the association between SUVR and MRI characteristics, with age and gender as covariates. The group difference of SUVR and gray matter volume were corrected for multiple comparison using false discover rate correction with q=0.05. Other comparisons were corrected using Gaussian random field correction. Results: Figure 1 shows the voxelwised comparisons of multiple imaging parameters between the two groups. The AD patients were with higher SUVR than HE in the posterior default mode network areas and bilateral temporal regions (peak t=7.05, p<0.0001), as well as dorsal frontal areas (peak t=6.57, p<0.0001). The GMV in AD patients was significantly smaller than that of HEs, with the most serious atrophy in the medial parietal, medial temporal lobes and orbital frontal areas (peak t=8.85, p<0.0001). fALFF were lower in the right inferior frontal areas (peak t=-4.47, p<0.0001). Compared to HEs, AD patients showed lower short-range FCS in the medial pre- and post-central gyrus (peak t=-5.37, p<0.0001), while weaker long-range FCS in lateral frontal and temporal areas (peak t=-5.20, p<0.0001). The association between SUVR and metrics derived from structural and functional MRI images in the AD group were demonstrated in Figure 2. Higher SUVR was associated with lower GMV in bilateral temporal lobe (peak t=-6.10, p<0.0001) and medial prefrontal cortices (peak t=-5.73, p<0.0001). SUVR was also positively correlated with FCS in the left middle occipital and angular gyrus (peak t=6.23, p<0.0001), which was mainly involved short-range connections (peak t=6.08, p<0.0001). We also find negative correlations in the HE group between SUVR and GMV (peak p=-6.70, p<0.0001) in a smaller cluster in the right insular. Conclusions: In the current study, Tau showed strong negative correlated with both focal structural and functional characteristics and functional connectivity strength,which support the view that tau is the driving force behind the neurodegeneration in AD. %U