Tractography-based quantitation of corticospinal tract development in premature newborns.
OBJECTIVE
To evaluate the impact of early brain injury and neonatal illness on corticospinal tract (CST) development in premature newborns serially studied with diffusion tensor tractography.


METHODS
Fifty-five premature newborns (median 27.6 weeks postmenstrual age) were scanned with magnetic resonance imaging (MRI) early in life and at term-equivalent age. Moderate-severe brain abnormalities (abnormal-MRI) were characterized by moderate-severe white matter injury or ventriculomegaly. Diffusion tensor tractography was used to measure CST diffusion parameters which reflect microstructural development: fractional anisotropy (FA) and average diffusivity (D(av)). The effect of abnormal-MRI and neonatal illness on FA and D(av) were assessed with multivariate regression for repeated measures adjusting for age at scan.


RESULTS
Twenty-one newborns (38%) had abnormal-MRI on either scan. FA increased with age significantly slower in newborns with abnormal-MRI (0.008/week) relative to newborns without these MRI abnormalities (0.011/wk) (interaction term P = .05). D(av) was higher in newborns with abnormal-MRI (1.5 x 10(-5) mm(2)/sec; P < .001) for any given age at scan. In the 23 newborns (42%) with postnatal infection, FA increased more slowly (interaction term P = .04), even when adjusting for the presence of abnormal-MRI.


CONCLUSIONS
CST microstructural development is significantly impaired in premature newborns with abnormal-MRI or postnatal infection, with a pattern of diffusion changes suggesting impaired glial cell development.
Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada.
Elysia
E
Adams
Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada.
Vann
V
Chau
Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada.
Kenneth J
KJ
Poskitt
Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada.
Ruth E
RE
Grunau
Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada.
Anne
A
Synnes
Department of Pediatrics, University of British Columbia, Vancouver, British Columbia, Canada; Department of Neurology, University of California, San Francisco, CA. Electronic address: smiller6@cw.bc.ca.
Steven P
SP
Miller
D056324:Diffusion Tensor Imaging; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000473:pathology; D007234:Infant, Premature; D007239:Infections / Q000473:pathology; D009457:Neuroglia / Q000473:pathology; D047928:Premature Birth / Q000503:physiopathology; D011446:Prospective Studies; D011712:Pyramidal Tracts / Q000473:pathology*