title: Normal range of intracranial translucency (IT) assessed by three-dimensional ultrasound at 11 + 0 to 13 + 6 weeks in a Chinese population.
abstract: OBJECTIVE
  To establish the reference range of intracranial translucency (IT) in the first trimester in a Chinese population.
  
  
  METHODS
  In a prospective study from March 2007 to June 2007, three-dimensional (3D) volumes of the fetal profile in the mid-sagittal plane were recorded from 102 normal pregnancies screened for trisomy 21 by the combination of fetal nuchal translucency (NT) thickness, maternal serum free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) at 11 + 0 to 13 + 6 weeks. 3D volumes were examined using multiplanar techniques. In the mid-sagittal plane the fourth ventricle presents as an (IT between the brain stem and choroid plexus. The anteroposterior diameter of IT in each case was measured. The relationship between IT with the other parameter was also examined.
  
  
  RESULTS
  The IT at first trimester ranged from 1.35 to 2.6 mm. There was no significant association between IT with NT, and serum biochemistry. The intraobserver and interobserver agreement was assessed in 20 (19.6%) normal cases. Mean (SD) differences of two observers was -0.015 (0.132) mm (p > 0.05). For each observer, mean (SD) between the 2 paired measurements were -0.001 (0.097) mm, and 0.010 (0.085) mm, respectively (p > 0.05).
  
  
  CONCLUSIONS
  In the first trimester, the reference range of IT in Chinese fetuses has been established. The assessment of IT is feasible and reproducible.
authors.affiliation: Department of Diagnostic Imaging, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, China. drchenmin2003@yahoo.com.hk
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.forename: Hui Fang
authors.initials: HF
authors.lastname: Wang
authors.forename: Tak
authors.initials: T
authors.lastname: Yeung Leung
authors.forename: Daljit
authors.initials: D
authors.lastname: Singh Sahota
authors.forename: Terence Tzu-Hsi
authors.initials: TT
authors.lastname: Lao
authors.forename: Tze Kin
authors.initials: TK
authors.lastname: Lau
mesh_terms: D000328:Adult; D044466:Asian People; D002681:China; D005260:Female; D020546:Fourth Ventricle / Q000000981:diagnostic imaging*; D005865:Gestational Age; D006801:Humans; D021621:Imaging, Three-Dimensional; D048208:Nuchal Translucency Measurement; D015588:Observer Variation; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D012016:Reference Values; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal