title: Evolution of subarachnoid space in normal fetuses using magnetic resonance imaging.
abstract: OBJECTIVE
  The purpose of this study was to measure the fetal subarachnoid spaces at different sites of the brain using magnetic resonance (MR) images and analyze them in relation to gestational age.
  
  
  METHODS
  Fetal MR images were obtained from 158 fetuses between 18 and 39 weeks of gestation who later showed no neurological problems. We bilaterally measured the distance between the superoanterior gyrus and the cranium as the frontal subarachnoid space (FSS) and the distance between the cortex in the parieto-occipital sulcus and the cranium as the parietal subarachnoid space (PSS). We also measured the cisterna magna between the cerebellar vermis and the cranium. Each of these was analyzed in relation to gestational age.
  
  
  RESULTS
  The width of the FSS began to decrease significantly at 32 weeks of gestation (P < 0.05). The width of the PSS started to decrease significantly at 34 weeks of gestation (P < 0.05). There was no difference between the right and left sides (P < 0.05). The size of the cisterna magna showed a positive correlation with gestational age (P < 0.05).
  
  
  CONCLUSIONS
  Measurement of the subarachnoid space is potentially useful for evaluating fetal development.
authors.affiliation: Department of Obstetrics and Gynecology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamimachi, Itabashi-ku, Tokyo, Japan. yu-hi@nyc.odn.ne.jp
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Seiji
authors.initials: S
authors.lastname: Abe
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Takagi
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Toshinori
authors.initials: T
authors.lastname: Kato
mesh_terms: D002946:Cisterna Magna / Q000196:embryology; D005260:Female; D005865:Gestational Age; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011247:Pregnancy; D012189:Retrospective Studies; D013346:Subarachnoid Space / Q000196:embryology*