Functional connectivity and metabolic effective connectivity patterns within default-mode network in healthy male adults revealed by hybrid PET/MR / 中华核医学与分子影像杂志

ABSTRACT

Objective:To study the functional connectivity (FC) and metabolic effective connectivity (MEC) patterns of the default mode network (DMN) in healthy male adults based on a novel hybrid PET/MR system.Methods:Fifteen healthy male adults with median age of 29 years were recruited locally in Xi′an from January to May 2019. All subjects went through PET/MR scan to get the whole brain 18F-fluorodeoxyglucose (FDG) PET, resting-state functional MRI (fMRI) and magnetization prepared rapid gradient echo (MPRAGE) T 1 weighted imaging data. CONN18b and statistical parametric mapping (SPM) 12 softwares were used to analyze data. The voxel-wise FC and FDG metabolic data were extracted within 4 sub-networks of DMN, which included medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC) and bilateral lateral parietal (LP). The FC and MEC between 4 sub-networks were calculated based on merged resting-state fMRI and metabolic data, and analyzed by one-sample t test separately, with Bonferroni correction. Results:FC pathways were all significant within 4 sub-networks of DMN ( t values 6.00-7.71, all P<0.008, Bonferroni corrected). Meanwhile, there were significant bi-directional MEC between MPFC and PCC(MPFC to PCC t=10.03; PCC to MPFC t=3.73, both P<0.004, Bonferroni corrected), as well as between bilateral LP (LP_L to LP_R t=5.28; LP_R to LP_L t=4.76, both P<0.004, Bonferroni corrected). There were significant uni-directional MEC from both MPFC and PCC to bilateral LP ( t values 3.44-6.93, all P<0.004, Bonferroni corrected). Conclusions:Special FC and MEC patterns exist within DMN. The closely interrelated MPFC and PCC play more important roles in DMN, and they may mediate LP jointly. The novel integrated PET/MR system will bring new perspective on the organization of brain networks, which may deepen the comprehensive understanding of DMN.