title: Diffusion-weighted imaging of the cerebellum in the fetus with Chiari II malformation.
abstract: OBJECTIVE
  Diffusion-weighted imaging can be used to characterize brain maturation. MR imaging of the fetus is used in cases of suspected Chiari II malformation when further evaluation of the posterior fossa is required. We sought to investigate whether there were any quantitative ADC abnormalities of the cerebellum in fetuses with this malformation.
  
  
  METHODS
  Measurements from ROIs acquired in each cerebellar hemisphere and the pons were obtained from calculated ADC maps performed on our Avanto 1.5T imaging system. Values in groups of patients with Chiari II malformations were compared with those from fetuses with structurally normal brains, allowing for the dependent variable of GA by using linear regression analysis.
  
  
  RESULTS
  There were 8 fetuses with Chiari II malformations and 23 healthy fetuses, ranging from 20 to 31 GW. There was a significant linear decline in the cerebellar ADC values with advancing gestation in our healthy fetus group, as expected. The ADC values of the cerebellum of fetuses with Chiari II malformation were higher [1820 (±100) × 10⁻⁶ mm²/s] than ADC values in the healthy fetuses (1370 ± 70) × 10⁻⁶ mm²/s. This was statistically significant, even when allowing for the dependent variable of GA (P = .0126). There was no significant difference between the pons ADC values in these groups (P = .645).
  
  
  CONCLUSIONS
  While abnormal white matter organization or early cerebellar degeneration could potentially contribute to our findings, the most plausible explanation pertains to abnormalities of CSF drainage in the posterior fossa, with increased extracellular water possibly accounting for this phenomenon.
authors.affiliation: Division of Neuroradiology, Department of Diagnostic Imaging, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada. cristina.philpott@sickkids.ca
authors.forename: C
authors.initials: C
authors.lastname: Mignone Philpott
authors.forename: P
authors.initials: P
authors.lastname: Shannon
authors.forename: D
authors.initials: D
authors.lastname: Chitayat
authors.forename: G
authors.initials: G
authors.lastname: Ryan
authors.forename: C A
authors.initials: CA
authors.lastname: Raybaud
authors.forename: S I
authors.initials: SI
authors.lastname: Blaser
mesh_terms: D001139:Arnold-Chiari Malformation / Q000196:embryology* / Q000473:pathology*; D002531:Cerebellum / Q000002:abnormalities* / Q000196:embryology / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011296:Prenatal Diagnosis / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity