title: Size of the intracranial optic nerve and optic tract in neonates at term-equivalent age at magnetic resonance imaging.
abstract: BACKGROUND
  The expected MRI-based dimensions of the intracranial optic nerve and optic tract in neonates are unknown.
  
  
  OBJECTIVE
  To evaluate the sizes of the intracranial optic nerve and optic tract in neonates at term-equivalent age using MRI.
  
  
  METHODS
  We retrospectively analyzed brain MRI examinations in 62 infants (28 boys) without intracranial abnormalities. The images were obtained in infants at term-equivalent age with a 1.5-tesla MRI scanner. We measured the widths and heights of the intracranial optic nerve and optic tract and calculated the cross-sectional areas using the formula for an ellipse.
  
  
  RESULTS
  The means ± standard deviation of the width, height and cross-sectional area of the intracranial optic nerve were 2.7 ± 0.2 mm, 1.7 ± 0.2 mm and 3.5 ± 0.5 mm(2), respectively. The width, height and cross-sectional area of the optic tract were 1.5 ± 0.1 mm, 1.6 ± 0.1 mm and 2.0 ± 0.2 mm(2), respectively. Using univariate and multivariate analyses, we found that postmenstrual age showed independent intermediate positive correlations with the width (r = 0.48, P < 0.01) and cross-sectional area (r = 0.40, P < 0.01) of the intracranial optic nerve. The lower bounds of the 95% prediction intervals for the width and cross-sectional area of the intracranial optic nerve were 0.07 × (postmenstrual age in weeks) - 0.46 mm, and 0.17 × (postmenstrual age in weeks) - 4.0 mm(2), respectively.
  
  
  CONCLUSIONS
  We identified the sizes of the intracranial optic nerve and optic tract in neonates at term-equivalent age. The postmenstrual age at MRI independently positively correlated with the sizes.
authors.affiliation: Department of Radiology, Tsuchiura Kyodo General Hospital, 11-7 Manabeshinmachi, Tsuchiura, Ibaraki, 300-0053, Japan. junoym@gmail.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Oyama
authors.affiliation: Department of Radiology, Tsuchiura Kyodo General Hospital, 11-7 Manabeshinmachi, Tsuchiura, Ibaraki, 300-0053, Japan.
authors.forename: Kouichi
authors.initials: K
authors.lastname: Mori
authors.affiliation: Department of Neonatology, Tsuchiura Kyodo General Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Imamura
authors.affiliation: Department of Ophthalmology, Tsuchiura Kyodo General Hospital, Tsuchiura, Ibaraki, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Mizushima
authors.affiliation: Departments of Diagnostic Radiology and Nuclear Medicine, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Ukihide
authors.initials: U
authors.lastname: Tateishi
mesh_terms: D000465:Algorithms; D059925:Anatomic Landmarks / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards*; D008297:Male; D009900:Optic Nerve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D065866:Optic Tract / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D009929:Organ Size; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Magnetic resonance imaging; Neonate; Optic nerve; Optic tract; Size