As summarized in Table our primary aim was to quantify

As summarized in Table 1, our primary aim was to quantify the test–retest reliability of a range of R-fMRI metrics in school-age children with and without ADHD. Several measures of test–retest reliability are available and have been used for R-fMRI (e.g., Thomason et al., 2011; Shehzad et al., 2009; Shou et al., 2013; Zuo et al., 2010a). In recognition of evidence of regional variation in test–retest reliability of R-fMRI metrics (see review, Zuo and Xing, 2014) the regional effects of ADHD on intrinsic glycoprotein inhibitors organization (Posner et al., 2014), and of its widespread use, we selected voxelwise intraclass correlation coefficient (ICC; Shrout and Fleiss, 1979) as our primary test–retest reliability measure. In addition to ICC, we also surveyed two other test–retest performance measures as they have been used in other imaging studies (e.g., Shehzad et al., 2009; Thomason et al., 2011; Zuo et al., 2010a), and provide complementary information to ICC. These include Kendall\'s Coefficient of Concordance (KCC; Kendall and Smith, 1939) – and image intraclass correlation coefficient (I2C2; Shou et al., 2013). KCC is the non-parametric counterpart of ICC assessing voxel-wise consistency between scans; I2C2 is a global measure of reliability that generalizes ICC to volumetric imaging data. Secondarily, we aimed to directly compare voxel-wise ICC between ADHD and TDC. To ensure that any differences in reliability observed between the two groups could be attributed to diagnostic status, as opposed to commonly observed differences in scanner head-motion, we ensured that the two groups were matched on head motion (e.g., mean frame-wise displacement; Jenkinson et al., 2002).
Materials and methods
Results
Discussion
Conclusions Within the same scan session, test–retest reliability in both children with ADHD and TDC is moderate to high for a range of R-fMRI measures. Although we detected regional differences in test–retest reliability between diagnostic groups, these were relatively circumscribed and varied across measures. While our results are encouraging, current limited understanding of the contributions of inter- and intra-subject variability to test–retest reliability underscores the need for large test–retest initiatives such as the Consortium for Reliability and Repeatability (CoRR; http://fcon_1000.projects.nitrc.org/indi/CoRR/html/).
Funding sources This work was supported by grants from National Institute of Mental Health (K23MH087770 to ADM; R01MH081218 to FXC; 5U01MH099059 to MPM); from the National Institute of Child Health and Human Development (R01HD065282 to FXC), the Stavros Niarchos Foundation (FXC and MPM); the Leon Levy Foundation (MPM, ADM, and CK); as well as the Major Joint Fund for International Cooperation and Exchange of the National Natural Science Foundation (81220108014), the Natural Science Foundation of China (81171409), the Chinese Academy of Sciences Key Research Program (CAS: KSZD-EW-TZ-002) and the support of the “CAS Hundred Talents” program to XNZ. No funding sources contributed to preparing gonorrhea manuscript.
Conflict of interest
Acknowledgments The authors are grateful to the children and parents who made this research possible. The authors also wish to thank the research staff of the Phyllis Green and Randolph Cowen Institute for Pediatric Neuroscience for help in participant recruitment, assessment, data collection and data entry, as well as Ms. Hallie Brown for editorial suggestions of an earlier version of the manuscript. We also thank the staff of NYU Center for Brain Imaging, Mr. Keith Sanzenbach, Dr. Pablo Velasco and Dr. Edward Vessel for their support. Many of the datasets included in this manuscript were deposited, as fully anonymized data, in the ADHD200 database (http://fcon_1000.projects.nitrc.org/indi/adhd200), and/or the Autism Brain Imaging Data Exchange repository (ABIDE; http://fcon_1000.projects.nitrc.org/indi/abide/data) and/or the National Database for Autism Research (NDAR; http://ndar.nih.gov/).