title: Relationship between first trimester visualization of the intracranial translucency and spina bifida.
abstract: OBJECTIVE
  To establish a reference range for the intracranial translucency (IT).
  
  
  METHODS
  In this prospective study, we examined 596 singleton fetuses at 11-14 weeks of gestation using transabdominal ultrasonography. The distribution curves of the anterior-posterior diameter of the IT were established according to the gestational weeks, and the percentiles for 11-14 weeks of gestation were calculated. Regression analysis was performed to estimate the relationship between the anterior-posterior diameter of the IT and other fetal biometric parameters.
  
  
  RESULTS
  The mean anterior-posterior diameter of the IT was 1.8 ± 0.4 mm. From 11 to 14 weeks of gestation, the IT diameter increased linearly with advancing gestation. The linear regression equation for the IT × crown-rump length (CRL) was IT = CRL × 0.0184 + 0.575 (R = 0.385, p < 0.001). The linear regression equation for the IT × biparietal diameter (BPD) was IT = BPD × 0.0532 + 0.632 (R = 0.346, p < 0.001). The linear regression equation for IT × gestational age (days) (GA) was ICT = GA × 0.024 - 0.339 (R = 0.25, p < 0.001). The linear regression analysis revealed significant correlations of the IT with CRL, BPD, and GA.
  
  
  CONCLUSIONS
  The IT increases linearly with increasing CRL, BPD, gestational age in weeks, and gestational age in days.
authors.affiliation: Obstetrics and Gynecology Department, Maternal Fetal Medicine Unit, Cerrahpaşa School of Medicine, Istanbul Universitesi, Istanbul, Turkey, maytacyuksel@gmail.com.
authors.forename: Mehmet Aytac
authors.initials: MA
authors.lastname: Yuksel
authors.forename: Resul
authors.initials: R
authors.lastname: Arisoy
authors.forename: Emre
authors.initials: E
authors.lastname: Erdogdu
authors.forename: Metehan
authors.initials: M
authors.lastname: Imamoglu
authors.forename: Murat
authors.initials: M
authors.lastname: Yayla
authors.forename: Cihat
authors.initials: C
authors.lastname: Sen
mesh_terms: D000328:Adult; D001699:Biometry; D003430:Cross-Sectional Studies; D018568:Crown-Rump Length; D005260:Female; D020546:Fourth Ventricle / Q000000981:diagnostic imaging*; D005865:Gestational Age; D006257:Head / Q000000981:diagnostic imaging*; D006801:Humans; D048208:Nuchal Translucency Measurement / Q000379:methods*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D012016:Reference Values; D012044:Regression Analysis; D016135:Spinal Dysraphism / Q000000981:diagnostic imaging*; D016216:Ultrasonography, Prenatal