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WHITE MATTER CHANGES IN LIPOPOLYSACCHARIDE-TREATED FETAL SHEEP MEASURED BY HIGH FIELD DIFFUSION TENSOR IMAGING
  1. Y Van de Looij1,2,
  2. J M Dean3,
  3. G Lodygensky4,
  4. F Lazeyras5,
  5. I Kjellmer6,
  6. R Gruetter2,5,7,
  7. C Mallard3,
  8. P S Huppi1,
  9. S V Sizonenko1
  1. 1Division of Development and Growth, Department of Pediatrics, Geneva University Hospital, Geneva, Switzerland,
  2. 2Laboratory of Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland,
  3. 3Perinatal Center, Department of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden,
  4. 4Department of Pediatrics, Washington University, St Louis, Missouri, USA,
  5. 5Department of Radiology, University of Geneva, Geneva, Switzerland,
  6. 6Department of Pediatrics, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden,
  7. 7Department of Radiology, University of Lausanne, Lausanne, Switzerland

Abstract

Lipopolysaccharide induces an inflammatory response and white matter injury in the developing brain. Diffusion tensor imaging measures the translational movement of water among the tissue in three-dimensional spatial directions. Fractional anisotropy (FA) a measure of the degree of preferential direction of water diffusivity is considered to reflect tissue microstructure organisation.

The aim of this study was to measure changes in white matter FA after fetal lipopolysaccharide exposure.

Fetal sheep received vehicle (control, n  =  7) or lipopolysaccharide (200 ng; n  =  7) at 103 days gestation (term 145 days). Fetal brains were collected after 10 days recovery and formalin-fixed for subsequent magnetic resonance imaging (9.4 T magnet). FA was measured in the corpus callosum (CC) and periventricular white matter (PVWM) in the anterior, median and posterior brain levels.

FA values in the lipopolysaccharide group were significantly lower than controls in the CC and PVWM: CC: anterior 0.67 ± 0.08 and 0.86 ± 0.06 p = 0.0023, middle 0.55 ± 0.08 and 0.66 ± 0.04 p = 0.0006 and posterior 0.76 ± 0.05 and 0.85 ± 0.04 p = 0.0012, respectively; PVWM: posterior 0.61 ± 0.11 and 0.78 ± 0.08 p = 0.01, respectively (Mann–Whitney test). FA levels in the PVWM anterior and middle slices showed a tendency to be lower in the lipopolysaccharide group (p = 0.053).

These lower FA levels reveal alteration in the developing white matter tracts after fetal exposure to lipopolysaccharide before the onset of myelination.

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