title: Differential vulnerability of white matter structures to experimental infantile hydrocephalus detected by diffusion tensor imaging.
abstract: OBJECTIVE
  The differential vulnerability of white matter (WM) to acute and chronic infantile hydrocephalus and the related effects of early and late reservoir treatment are unknown, but diffusion tensor imaging (DTI) could provide this information. Thus, we characterized WM integrity using DTI in a clinically relevant model.
  
  
  METHODS
  Obstructive hydrocephalus was induced in 2-week-old felines by intracisternal kaolin injection. Ventricular reservoirs were placed 1 (early) or 2 (late) weeks post-kaolin and tapped frequently based solely on neurological deficit. Hydrocephalic and age-matched control animals were sacrificed 12 weeks postreservoir. WM integrity was evaluated in the optic system, corpus callosum, and internal capsule prereservoir and every 3 weeks using DTI. Analyses were grouped as acute (<6 weeks) or chronic (≥6 weeks).
  
  
  RESULTS
  In the corpus callosum during acute stages, fractional anisotropy (FA) decreased significantly with early and late reservoir placement (p = 0.0008 and 0.0008, respectively), and diffusivity increased significantly in early (axial, radial, and mean diffusivity, p = 0.0026, 0.0012, and 0.0002, respectively) and late (radial and mean diffusivity, p = 0.01 and 0.0038, respectively) groups. Chronically, the corpus callosum was thinned and not detectable by DTI. FA was significantly lower in the optic chiasm and tracts (p = 0.0496 and 0.0052, respectively) with late but not early reservoir placement. In the internal capsule, FA in both reservoir groups increased significantly with age (p < 0.05) but diffusivity remained unchanged.
  
  
  CONCLUSIONS
  All hydrocephalic animals treated with intermittent ventricular reservoir tapping demonstrated progressive ventriculomegaly. Both reservoir groups demonstrated WM integrity loss, with the CC the most vulnerable and the optic system the most resilient.
authors: Stanford Children's Health, Lucile Packard Children's Hospital, 725 Welch Road, Palo Alto, CA, USA, eskandar@musc.edu.
authors: Ramin
authors: R
authors: Eskandari
authors: Osama
authors: O
authors: Abdullah
authors: Cameron
authors: C
authors: Mason
authors: Kelley E
authors: KE
authors: Lloyd
authors: Amanda N
authors: AN
authors: Oeschle
authors: James P
authors: JP
authors: McAllister
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D002415:Cats; D003337:Corpus Callosum / Q000473:pathology; D056324:Diffusion Tensor Imaging; D004195:Disease Models, Animal; D006849:Hydrocephalus / Q000175:diagnosis*; D007091:Image Processing, Computer-Assisted; D020772:Internal Capsule / Q000473:pathology; D008279:Magnetic Resonance Imaging; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D009897:Optic Chiasm / Q000473:pathology; D065866:Optic Tract / Q000473:pathology; D018709:Statistics, Nonparametric; D013997:Time Factors; D066127:White Matter / Q000473:pathology*