title: Functional connectivity in BOLD and CBF data: similarity and reliability of resting brain networks.
abstract: Resting-state functional connectivity (FC) fMRI (rs-fcMRI) offers an appealing approach to mapping the brain's intrinsic functional organization. Blood oxygen level dependent (BOLD) and arterial spin labeling (ASL) are the two main rs-fcMRI approaches to assess alterations in brain networks associated with individual differences, behavior and psychopathology. While the BOLD signal is stronger with a higher temporal resolution, ASL provides quantitative, direct measures of the physiology and metabolism of specific networks. This study systematically investigated the similarity and reliability of resting brain networks (RBNs) in BOLD and ASL. A 2 × 2 × 2 factorial design was employed where each subject underwent repeated BOLD and ASL rs-fcMRI scans on two occasions on two MRI scanners respectively. Both independent and joint FC analyses revealed common RBNs in ASL and BOLD rs-fcMRI with a moderate to high level of spatial overlap, verified by Dice Similarity Coefficients. Test-retest analyses indicated more reliable spatial network patterns in BOLD (average modal Intraclass Correlation Coefficients: 0.905 ± 0.033 between-sessions; 0.885 ± 0.052 between-scanners) than ASL (0.545 ± 0.048; 0.575 ± 0.059). Nevertheless, ASL provided highly reproducible (0.955 ± 0.021; 0.970 ± 0.011) network-specific CBF measurements. Moreover, we observed positive correlations between regional CBF and FC in core areas of all RBNs indicating a relationship between network connectivity and its baseline metabolism. Taken together, the combination of ASL and BOLD rs-fcMRI provides a powerful tool for characterizing the spatiotemporal and quantitative properties of RBNs. These findings pave the way for future BOLD and ASL rs-fcMRI studies in clinical populations that are carried out across time and scanners.
authors.affiliation: Department of Neurology, UCLA, 90025 Los Angeles, USA. Electronic address: kayjann@ucla.edu.
authors.forename: Kay
authors.initials: K
authors.lastname: Jann
authors.affiliation: Department of Psychology, UCLA, 90025 Los Angeles, USA.
authors.forename: Dylan G
authors.initials: DG
authors.lastname: Gee
authors.affiliation: Department of Neurology, UCLA, 90025 Los Angeles, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Kilroy
authors.affiliation: Department of Psychiatric Neurophysiology, University Hospital of Psychiatry, University Bern, 3000 Bern 60, Switzerland.
authors.forename: Simon
authors.initials: S
authors.lastname: Schwab
authors.affiliation: Department of Neurology, UCLA, 90025 Los Angeles, USA.
authors.forename: Robert X
authors.initials: RX
authors.lastname: Smith
authors.affiliation: Department of Psychology, Yale University, 06520 New Haven, USA.
authors.forename: Tyrone D
authors.initials: TD
authors.lastname: Cannon
authors.affiliation: Department of Neurology, UCLA, 90025 Los Angeles, USA.
authors.forename: Danny J J
authors.initials: DJ
authors.lastname: Wang
mesh_terms: D000328:Adult; D000465:Algorithms; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D063132:Connectome / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D015203:Reproducibility of Results; D012146:Rest / Q000502:physiology; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen
keywords: Arterial spin labeling; Default mode network; Functional connectivity; Resting-state; Test–retest repeatability