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AJNR - American Journal of Neuroradiology

Publication Preview: Published September 10, 2008

American Journal of Neuroradiology 2008;29:1883.

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American Journal of Neuroradiology
DOI 10.3174/ajnr.A1256

FUNCTIONAL

Functional Connectivity MR Imaging Reveals Cortical Functional Connectivity in the Developing Brain

W. Lin, Q. Zhu, W. Gao, Y. Chen, C.-H. Toh, M. Styner, G. Gerig, J.K. Smith, B. Biswal and J.H. Gilmore

From the Departments of Radiology (W.L., Y.C., J.K.S.), Biomedical Engineering (W.G.), and Psychiatry (J.H.G., M.S.), University of North Carolina at Chapel Hill, Chapel Hill, NC; Department of Electrical and Computer Engineering (Q.Z.), Duke University, Durham, NC; Department of Medical Imaging and Intervention (C.-H.T.), Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Tao-Yuan, Taiwan; Scientific Computing and Imaging Institute (G.G.), Utah University, Salt Lake City, Utah; and Department of Radiology (B.B.), University of Medicine and Dentistry of New Jersey, Newark, NJ.

Please address correspondence to Weili Lin, PhD, University of North Carolina at Chapel Hill, Department of Radiology, CB #7515, Chapel Hill, NC 27599; e-mail: weili_lin{at}med.unc.edu

BACKGROUND AND PURPOSE: Unlike conventional functional MR imaging where external sensory/cognitive paradigms are needed to specifically activate different regions of the brain, resting functional connectivity MR imaging acquires images in the absence of cognitive demands (a resting condition) and detects brain regions, which are highly temporally correlated. Therefore, resting functional MR imaging is highly suited for the study of brain functional development in pediatric subjects. This study aimed to determine the temporal and spatial patterns of rfc in healthy pediatric subjects between 2 weeks and 2 years of age.

MATERIALS AND METHODS: Rfc studies were performed on 85 children: 38 neonates (2–4 weeks of age), 26 one-year-olds, and 21 two-year-olds. All subjects were imaged while asleep; no sedation was used. Six regions of interest were chosen, including the primary motor, sensory, and visual cortices in each hemisphere. Mean signal intensity of each region of interest was used to perform correlation analysis pixel by pixel throughout the entire brain, identifying regions with high temporal correlation.

RESULTS: Functional connectivity was observed in all subjects in the sensorimotor and visual areas. The percent brain volume exhibiting rfc and the strength of rfc continued to increase from 2 weeks to 2 years. The growth trajectories of the percent brain volume of rfc appeared to differ between the sensorimotor and visual areas, whereas the z-score was similar. The percent brain volume of rfc in the sensorimotor area was significantly larger than that in the visual area for subjects 2 weeks of age (P = .008) and 1-year-olds (P = .017) but not for the 2-year-olds.

CONCLUSIONS: These findings suggest that rfc in the sensorimotor precedes that in the visual area from 2 weeks to 1 year but becomes comparable at 2 years. In contrast, the comparable z-score values between the sensorimotor and visual areas for all age groups suggest a disassociation between percent brain volume and the strength of cortical rfc.