title: The influence of image setting on intracranial translucency measurement by manual and semi-automated system.
abstract: OBJECTIVE
  To investigate the agreement between manual and semi-automated system and the effect of different image settings on intracranial translucency (IT) measurement.
  
  
  METHODS
  A prospective study was conducted on 55 women carrying singleton pregnancy who attended first trimester Down syndrome screening. IT was measured both manually and by semi-automated system at the same default image setting. The IT measurements were then repeated with the post-processing changes in the image setting one at a time. The difference in IT measurements between the altered and the original images were assessed.
  
  
  RESULTS
  Intracranial translucency was successfully measured on 55 images both manually and by semi-automated method. There was strong agreement in IT measurements between the two methods with a mean difference (manual minus semi-automated) of 0.011 mm (95% confidence interval--0.052 mm-0.094 mm). There were statistically significant variations in both manual and semi-automated IT measurement after changing the Gain and the Contrast. The greatest changes occurred when the Contrast was reduced to 1 (IT reduced by 0.591 mm in semi-automated; 0.565 mm in manual), followed by when the Gain was increased to 15 (IT reduced by 0.424 mm in semi-automated; 0.524 mm in manual).
  
  
  CONCLUSIONS
  The image settings may affect IT identification and measurement. Increased Gain and reduced Contrast are the most influential factors and may cause under-measurement of IT.
authors: Fetal Medicine Unit, Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors: Li
authors: L
authors: Zhen
authors: Xin
authors: X
authors: Yang
authors: Yuen Ha
authors: YH
authors: Ting
authors: Min
authors: M
authors: Chen
authors: Tak Yeung
authors: TY
authors: Leung
mesh_terms: D000328:Adult; D001331:Automation; D018568:Crown-Rump Length; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D048208:Nuchal Translucency Measurement / Q000295:instrumentation / Q000379:methods*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012886:Skull / Q000000981:diagnostic imaging; D055815:Young Adult