Toward reliable characterization of functional homogeneity in the human brain: Preprocessing, scan duration, imaging resolution and computational space

• Published in: NeuroImage (Orlando, Fla.) Vol. 65; pp. 374 - 386
• Main Authors: Zuo, Xi-Nian, Xu, Ting, Jiang, Lili, Yang, Zhi, Cao, Xiao-Yan, He, Yong, Zang, Yu-Feng, Castellanos, F. Xavier, Milham, Michael P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 15.01.2013; Elsevier; Elsevier Limited
• Subjects: Advantages; Alzheimer's disease; Attention deficit hyperactivity disorder; Autism; Biological and medical sciences; Brain - anatomy & histology; Brain - physiology; Brain Mapping - methods; Connectome; Data processing; Default network; Functional homogeneity; Fundamental and applied biological sciences. Psychology; Humans; Image Interpretation, Computer-Assisted - methods; Magnetic Resonance Imaging; Neural Pathways - anatomy & histology; Neural Pathways - physiology; Reliability; Reproducibility of Results; Test–retest; Vertebrates: nervous system and sense organs; Default network; Test–retest; Connectome; Functional homogeneity; Reliability; Characterization; Human; Imaging; Central nervous system; Duration; Test―retest; Encephalon
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2012.10.017

While researchers have extensively characterized functional connectivity between brain regions, the characterization of functional homogeneity within a region of the brain connectome is in early stages of development. Several functional homogeneity measures were proposed previously, among which regional homogeneity (ReHo) was most widely used as a measure to characterize functional homogeneity of resting state fMRI (R-fMRI) signals within a small region (Zang et al., 2004). Despite a burgeoning literature on ReHo in the field of neuroimaging brain disorders, its test–retest (TRT) reliability remains unestablished. Using two sets of public R-fMRI TRT data, we systematically evaluated the ReHo's TRT reliability and further investigated the various factors influencing its reliability and found: 1) nuisance (head motion, white matter, and cerebrospinal fluid) correction of R-fMRI time series can significantly improve the TRT reliability of ReHo while additional removal of global brain signal reduces its reliability, 2) spatial smoothing of R-fMRI time series artificially enhances ReHo intensity and influences its reliability, 3) surface-based R-fMRI computation largely improves the TRT reliability of ReHo, 4) a scan duration of 5min can achieve reliable estimates of ReHo, and 5) fast sampling rates of R-fMRI dramatically increase the reliability of ReHo. Inspired by these findings and seeking a highly reliable approach to exploratory analysis of the human functional connectome, we established an R-fMRI pipeline to conduct ReHo computations in both 3-dimensions (volume) and 2-dimensions (surface). [Display omitted] ► Motion and non-brain tissue correction significantly improve the ReHo's reliability. ► Global brain signal regression significantly reduces the ReHo's reliability. ► 5min scan duration is enough to achieve reliable ReHo estimates. ► Surface-based analysis produces highly reliable ReHo measures. ► Multi-band EPI resting-state brain dramatically increases the reliability of ReHo.