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AJNR - American Journal of Neuroradiology

Publication Preview: Published October 2, 2008

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American Journal of Neuroradiology
DOI 10.3174/ajnr.A1304

PEDIATRICS

Quantitative Fiber Tracking Analysis of the Optic Radiation Correlated with Visual Performance in Premature Newborns

J.I. Berman, H.C. Glass, S.P. Miller, P. Mukherjee, D.M. Ferriero, A.J. Barkovich, D.B. Vigneron and R.G. Henry

From the Departments of Radiology (J.I.B., P.M., D.B.V., R.G.H., A.J.B.), Neurology (H.C.G., S.P.M., D.M.F., A.J.B.), and Pediatrics (H.C.G., D.M.F., A.J.B.), University of California-San Francisco, San Francisco, Calif.

Please address correspondence to Jeffrey Berman, PhD, 185 Berry St, Suite 350, San Francisco, CA 94107; e-mail: jberman{at}radiology.ucsf.edu

BACKGROUND AND PURPOSE: Many prematurely born neonates have abnormalities of vision or visual processing. This study tests the hypothesis that a correlation exists between the microstructure of the optic radiation and visual performance in premature neonates.

MATERIALS AND METHODS: Diffusion tensor imaging (DTI) was performed on 36 premature neonates ranging in age from 29 to 41 weeks of gestational age (GA) at time of MR imaging. DTI fiber tracking methods were developed to delineate the optic radiations and segment the tract into anterior, middle, and posterior regions. Structural development and spatial heterogeneity in the delineated optic radiations were quantitatively assessed with diffusion tensor parameters including fractional anisotropy (FA), directionally averaged diffusivity (D_av), parallel diffusivity (₁), and transverse diffusivity (). Visual maturity of the preterm neonates at the time of MR imaging was assessed with a visual fixation task. Regression analysis was used to examine the relationship between neonatal visual performance and the microstructure of the optic radiation.

RESULTS: Fractional anisotropy within the optic radiation was observed to increase with GA (P < .0001). D_av, parallel diffusivity, and transverse diffusivity within the optic radiation each decreased with GA (P < .0003, P < .02, and P < .0001, respectively). The anterior segment of the optic radiation exhibited higher FA and lower D_av, parallel diffusivity, and transverse diffusivity (P < .005 each) than within the middle and posterior segments. Optic radiation fractional anisotropy correlated significantly with scores from the visual fixation tracking assessment, independent of GA (P < .006).

CONCLUSIONS: This study detected a significant link between the tissue architecture of the optic radiation and visual function in premature neonates.