title: Periventricular hyperintensity in children with hydrocephalus.
abstract: BACKGROUND
  Magnetic resonance images of children with hydrocephalus often include a rim of hyperintensity in the periventricular white matter (halo).
  
  
  OBJECTIVE
  The purpose of this study was to decide between the hypothesis that the halo is caused by cerebrospinal fluid (CSF) flow during the cardiac cycle, and the alternate hypothesis that the halo is caused by anatomical changes (stretching and compression of white matter).
  
  
  METHODS
  Participants were selected from a multicenter imaging study of pediatric hydrocephalus. We compared 19 children with hydrocephalus to a group of 52 controls. We quantified ventricle enlargement using the frontal-occipital horn ratio. We conducted qualitative and quantitative analysis of diffusion tensor imaging in the corpus callosum and posterior limb of the internal capsule. Parameters included the fractional anisotropy (FA), mean diffusivity, axial diffusivity and radial diffusivity.
  
  
  RESULTS
  The halo was seen in 16 of the 19 children with hydrocephalus but not in the controls. The corpus callosum of the hydrocephalus group demonstrated FA values that were significantly decreased from those in the control group (P = 4 · 10(-6)), and highly significant increases were seen in the mean diffusivity and radial diffusivity in the hydrocephalus group. In the posterior limb of the internal capsule the FA values of the hydrocephalus group were higher than those for the control group (P = 0.002), and higher values in the hydrocephalus group were also noted in the axial diffusivity. We noted correlations between the diffusion parameters and the frontal-occipital horn ratio.
  
  
  CONCLUSIONS
  Our results strongly support the hypothesis that the halo finding in hydrocephalus is caused by structural changes rather than pulsatile CSF flow.
authors.affiliation: Department of Neurological Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO, USA.
authors.forename: S Hassan A
authors.initials: SH
authors.lastname: Akbari
authors.forename: David D
authors.initials: DD
authors.lastname: Limbrick
authors.forename: Robert C
authors.initials: RC
authors.lastname: McKinstry
authors.forename: Mekibib
authors.initials: M
authors.lastname: Altaye
authors.forename: Dustin K
authors.initials: DK
authors.lastname: Ragan
authors.forename: Weihong
authors.initials: W
authors.lastname: Yuan
authors.forename: Francesco T
authors.initials: FT
authors.lastname: Mangano
authors.forename: Scott K
authors.initials: SK
authors.lastname: Holland
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Shimony
mesh_terms: D000293:Adolescent; D016880:Anisotropy; D002648:Child; D002675:Child, Preschool; D003337:Corpus Callosum / Q000473:pathology*; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000473:pathology*; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D066127:White Matter / Q000473:pathology*