| IntroductionSex differences of brain metabolic networks are attracting increasing,well-deserved attention from neuroscientists.A vast variety of studies showed that brain metabolic networks differ between males and females for almost all neuropsychiatric ailments.However,gender differences in some specific nodes and functional connectivities of brain functional networks are still controversial.Therefore,it is necessary to identify more available and scientific methods to explore the gender differences in brain metabolic networks at resting state.Increased synaptic activity can cause elevated glucose use,which can be reliably imaged by positron emission tomography(PET).So regional cerebral glucose metabolism(rCMglc)measured by resting 18F-fluorodeoxyglucose PET(RS 18F-FDG PET)can be viwed as an efficient tool for assessing synaptic function.Furthermore,there is no RS 18F-FDG PET study on gender differences in cerebral metabolic pathways employing graph-based approaches in resting state so far.So at present study(part ?),we try to use 18F-FDG-PET mapping the brain Hub regions and functional connectome in healthy people and revealing their gender differences of FDG-PET metabolic brain networks.Cancer is a high motality disease accompanied with an increased risk of depression and altered functional brain network topology.Some studies demon-strate functional and structural imbalance or disruption of brain networks frequently occur following chemotherapy in cancer patients.Other studies reveal depression and similar symptoms frequently occur in cancer patients following diagnosis,seriously influence the cognitive function,and cause memory impairment,and suggest depression-related factors may contribute to the less optimal network topology in the metabolic brain network of cancer patients.Therefore,there was still a controversial issure on whether it is depression or chemotherapy that causes the change of brain topological structure in patients with cancer.And so far,few studies have focused on the topological organization of the metabolic brain network in cancer with depression,especially those without chemotherapy.So,investigating the metabolic brain network in pre-chemotherapy cancer with depression could bring new insights into the information regarding the neurophysiological mechanisms.AT present study(part II),we aimed to investigate the metabolic brain network and its relation-ship with depression symptoms using 18F-fluorodeoxyglucose positron emission tomography,and expected that investigating the metabolic brain network in cancer patients could provide a new avenue for exploring the information regarding the neurophysiological mechanisms and providing scientific evidence for early mental intervention and clinical decision-making.Part I Gender Differences of FDG-PET Brain Metabolic NetworksPurposeThis study aimed to investigate gender differences of glucose metabolic network in brains of healthy adult at resting state by using 18F-fluorodeoxy-glucose positron emission tomography,and expected to provide gender-related reference for scientific research and clinical decision making.Materials and MethodsFDG-PET data of 204 right-handed,healthy individuals(100 females and 104 males)were used to construct brain metabolic networks,whose nodal and global parameters(Clustering coefficient(Cp),Characteristic path length(Lp)and Betweenness centrality(Cb)were analyzed by graph theory.ResultsOur results showed that the brain metabolic networks derived from FDG-PET data were with small-world properties in both male and female groups.The male group had higher clustering coefficient compared with females,but longer absolute path length.However,no significant between-group difference of Cpand Lp was found.Compared with females,nodal centrality in males was signify-cantly reduced(Permutation test with 1000 repetitions,P<0.05)in left postcentral gyrus(Postcentral_L),right angular gyrus(Angular_R)and left temporal pole/middle temporal gyrus(Temporal_Pole_Mid_L);and it was increased(Permutation test with 1000 repetitions,P<0.05)in left amyg-dale(Amygdala_L),left precuneus(Precuneus_L),right temporal pole/middle temporal gyrus(Temporal_Pole_Mid_R)and left inferior temporal gyrus(Temporal_Inf_L).Our results revealed gender-related differences of topological structure in whole-brain metabolic networks.ConclusionsGender must be considered as a covariate while designing experiments,accounting for cerebral metabolic data from normal control and experimental patients as well as making clinical decisions.Our results might be beneficial for further grasp of sex differences in cerebral activities.Part ? Topological Organization of Metabolic BrainNetworks in Pre-Chemotherapy Cancer with Depression:A Resting-State PET Study AbstractPurposeThis study aimed to investigate the alterations of metabolic brain networks in cancer patients with depression symptoms at resting state before chemo-therapy by using 18F-fluorodeoxyglucose positron emission tomography,and ecpected to provide a new way for exploring the neurobiological mechanism and a scientific evidence for early mental intervention and clinical decision-making.Materials and MethodsWe use 18F-fluorodeoxyglucose positron emission tomography data in 78 prechemotherapy cancer patients with depression and 80 matched healthy subjects to construct brain metabolic networks.The regional cerebral glucose metabolism(rCMglc),Beck depression inventory scores(BDIs),nodal and global parameters(Cp,Lp,and Cb)of the metabolic brain network in cancer patients with depression and normal controls(NCs)were computed,their between-group differences were alalyzed by grapy theory,The rCMglc and BDIs in cancer patients with depression were related.ResultsSignificant decreases in metabolism were found in the frontal and temporal gyri in cancer patients compared with healthy subjects(two sample t-test,P<0.05,false discovery rate,FDR,P<0.01).Negative correlations between depression and metabolism were found predominantly in the inferior frontal and cuneus regions(r=-0.3278,-0.3216,P<0.05),whereas positive correlations were observed in eight regions,primarily including the left rolandic operculum(Rolandic_Oper_L,r=0.3337,P<0.05),the left insula(Insula_L,r=0.3645,P<0.05),hippocampus(Hippocampus_L,Hippocampus_R,r=0.3609,0.3425,P<0.05),the right para-hippocampus(ParaHippocampal_R,r=0.3338,P<0.05),amygdale(Amygdala_L,Amygdala_R,r=0.3122,0.3263,P<0.05),Temporal pole:middle temporal gyrus(Temporal_Pole_Mid_R,r=0.3338,P<0.05).Furthermore,a higher clustering efficiency,longer path length were found in cancer patients compared with healthy subjects.Significant decreases in nodal betweenness centralities were found in some brain regions,such as the train-gular part of the inferior frontal gyrus,the orbital part of the middle frontal gyrus,the olfactory cortex,the Heschl gyrus,the caudate nucleus,the bilateral hippo-campus,the right para-hippocampus,the amygdale,and the anterior cingulated,in cancer patients compared with NCs,whereas significant increases in nodal betweenness centralities were found in orther regions mainly including the middle frontal gyrus,insula,superior occipital gyrus,and pallidum(Permutation test with 1000 repetitions,P<0.05).ConclusionAlthough the metabatic brain networks of cancer patients preserved the small-world properties,but the topological architecture was found with partial loss of optimal pattern.The hypo-metabolism and its relationship with BDIs may help explain the dysfunction and inefficiency of the metabolic brain network following the disease.The abnormalities in global and regional parameters were mainly observed in the frontal and temporal lobes as well as the limbic regions,which would be critical to the understanding of the neurobiological mechanism associated with depression symptoms in pre-chemotherapy cancer.The present findings may provide a new avenue for exploring the neurobiological mechanism,which plays a key role in lessening the depression effects in pre-chemotherapy cancer patients. |
PDF Full Text Request