title: Relationship between simultaneously acquired resting-state regional cerebral glucose metabolism and functional MRI: a PET/MR hybrid scanner study.
abstract: Recently introduced hybrid PET/MR scanners provide the opportunity to measure simultaneously, and in direct spatial correspondence, both metabolic demand and functional activity of the brain, hence capturing complementary information on the brain's physiological state. Here we exploited PET/MR simultaneous imaging to explore the relationship between the metabolic information provided by resting-state fluorodeoxyglucose-PET (FDG-PET) and fMRI (rs-fMRI) in neurologically healthy subjects. Regional homogeneity (ReHo), fractional amplitude of low frequency fluctuations (fALFF), and degree of centrality (DC) maps were generated from the rs-fMRI data in 23 subjects, and voxel-wise comparison to glucose uptake distribution provided by simultaneously acquired FDG-PET was performed. The mutual relationships among each couple of these four metrics were explored in terms of similarity, both of spatial distribution across the brain and the whole group, and voxel-wise across subjects, taking into account partial volume effects by adjusting for grey matter (GM) volume. Although a significant correlation between the spatial distribution of glucose uptake and rs-fMRI derived metrics was present, only a limited percentage of GM voxels correlated with PET across subjects. Moreover, the correlation between the spatial distributions of PET and rs-fMRI-derived metrics is spatially heterogeneous across both anatomic regions and functional networks, with lowest correlation strength in the limbic network (Spearman rho around -0.11 for DC), and strongest correlation for the default-mode network (up to 0.89 for ReHo and 0.86 for fALFF). Overall, ReHo and fALFF provided significantly higher correlation coefficients with PET (p=10(-8) and 10(-7), respectively) as compared to DC, while no significant differences were present between ReHo and fALFF. Local GM volume variations introduced a limited overestimation of the rs-fMRI to FDG correlation between the modalities under investigation through partial volume effects. These novel results provide the basis for future studies of alterations of the coupling between brain metabolism and functional connectivity in pathologic conditions.
authors: IRCCS SDN, Istituto di Ricerca Diagnostica e Nucleare, Via E. Gianturco 113, 80143 Naples, Italy. Electronic address: maiello@sdn-napoli.it.
authors: Marco
authors: M
authors: Aiello
authors: Department of Neurosciences, Reproductive Sciences and Odontostomatology, Federico II University, via S. Pansini 5-ed. 17, I-80131 Naples, Italy.
authors: Elena
authors: E
authors: Salvatore
authors: INSERM U894, Université Paris Descartes, Centre Hospitalier Sainte-Anne, Sorbonne Paris Cité, Paris, France; CNRS U8240, Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Institut Universitaire de France, Paris, France.
authors: Arnaud
authors: A
authors: Cachia
authors: Biostructure and Bioimaging Institute, National Research Council, Via T. De Amicis 95, 80145 Naples, Italy.
authors: Sabina
authors: S
authors: Pappatà
authors: IRCCS SDN, Istituto di Ricerca Diagnostica e Nucleare, Via E. Gianturco 113, 80143 Naples, Italy.
authors: Carlo
authors: C
authors: Cavaliere
authors: Biostructure and Bioimaging Institute, National Research Council, Via T. De Amicis 95, 80145 Naples, Italy.
authors: Anna
authors: A
authors: Prinster
authors: IRCCS SDN, Istituto di Ricerca Diagnostica e Nucleare, Via E. Gianturco 113, 80143 Naples, Italy.
authors: Emanuele
authors: E
authors: Nicolai
authors: IRCCS SDN, Istituto di Ricerca Diagnostica e Nucleare, Via E. Gianturco 113, 80143 Naples, Italy.
authors: Marco
authors: M
authors: Salvatore
authors: INSERM U894, Université Paris Descartes, Centre Hospitalier Sainte-Anne, Sorbonne Paris Cité, Paris, France.
authors: Jean-Claude
authors: JC
authors: Baron
authors: Biostructure and Bioimaging Institute, National Research Council, Via T. De Amicis 95, 80145 Naples, Italy.
authors: Mario
authors: M
authors: Quarantelli
mesh_terms: D000328:Adult; D001923:Brain Chemistry / Q000502:physiology*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D064847:Multimodal Imaging; D009415:Nerve Net / Q000502:physiology; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012146:Rest / Q000502:physiology*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose
keywords: Functional connectivity; Networks; PET/MRI; Resting-state fMRI; [(18)F]FDG