目的:用一体化PET/MR研究健康年轻男性脑默认网络(DMN)的功能连接(FC)和代谢有效连接(MEC)特征。方法:于2019年1月至2019年5月在西安招募15名健康男性受试者(中位年龄29岁)，使用PET/MR采集所有受试者全脑的n 18F-脱氧葡萄糖(FDG) PET、静息功能MRI(fMRI)以及磁化准备快速梯度回波序列(MPRAGE)Tn 1加权数据。使用CONN18b软件和统计参数图(SPM)12进行分析，基于体素提取DMN 4个子网络：内侧前额叶皮质(MPFC)、后扣带回皮质(PCC)及左右两侧的外侧顶叶(LP)的FC及FDG代谢数据，计算FC和MEC并分别进行单样本n t检验，统计结果经Bonferroni校正。n 结果:DMN的4个子网络两两之间存在有统计学意义的FC(n t值：6.00～7.71，均n P<0.008，Bonferroni校正)；MPFC与PCC之间(MPFC到PCC:n t＝10.03, PCC到MPFC: n t＝3.73，均n P<0.004，Bonferroni校正)、双侧LP相互之间(左LP到右LP:n t＝5.28，右LP到左LP: n t＝4.76，均n P<0.004，Bonferroni校正)存在有统计学意义的双向MEC；MPFC、PCC分别和双侧LP之间存在有统计学意义的单向MEC(n t值：3.44～6.93，均n P<0.004，Bonferroni校正)。n 结论:DMN内部存在特殊的FC和MEC模式，MPFC和PCC在DMN中较为关键，存在紧密联系且共同调节LP。一体化PET/MR提供了认识脑网络组织形式的新角度，深化了对DMN的全面了解。“,”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 n 18F-fluorodeoxyglucose (FDG) PET, resting-state functional MRI (fMRI) and magnetization prepared rapid gradient echo (MPRAGE) Tn 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 n t test separately, with Bonferroni correction.n Results:FC pathways were all significant within 4 sub-networks of DMN (n t values: 6.00-7.71, all n P<0.008, Bonferroni corrected). Meanwhile, there were significant bi-directional MEC between MPFC and PCC(MPFC to PCC:n t=10.03; PCC to MPFC: n t=3.73, both n P<0.004, Bonferroni corrected), as well as between bilateral LP (LP_L to LP_R:n t=5.28; LP_R to LP_L: n t=4.76, both n P<0.004, Bonferroni corrected). There were significant uni-directional MEC from both MPFC and PCC to bilateral LP (n t values: 3.44-6.93, all n P<0.004, Bonferroni corrected).n 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.