title: Effect of image settings on nuchal translucency thickness measurement by a semi-automated system.
abstract: OBJECTIVE
  To investigate whether pre- and post-processing image settings affect NT measurements made by a semi-automatic method (SAM).
  
  
  METHODS
  Different image settings (e.g. gain) were either adjusted one at a time on images that had been obtained during fetal NT scans (post-processing, n = 66), or adjusted one at a time during live scanning and image acquisition of the adult posterior tibial artery (pre-processing group, n = 91). The NT and luminal diameter of the posterior tibial artery, respectively, were measured by SAM on all original and adjusted images.
  
  
  RESULTS
  Alteration of the image settings resulted in a statistically significant effect on the measurements taken by SAM, with an average pair difference ranging from 0.001 mm to 0.139 mm. Most of the differences were small and therefore the clinical impact would be negligible. The pair differences were greatest with a very high contrast setting, or without tissue harmonic imaging (THI); the paired difference in measurement in those with vs those without THI was more than 0.1 mm in over 40% of cases.
  
  
  CONCLUSIONS
  Measurements made by SAM are affected by image settings.
authors: Fetal Medicine Unit, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, PR China.
authors: P W
authors: PW
authors: Chen
authors: M
authors: M
authors: Chen
authors: T Y
authors: TY
authors: Leung
authors: T K
authors: TK
authors: Lau
mesh_terms: D001330:Electronic Data Processing; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D048208:Nuchal Translucency Measurement / Q000379:methods; D015588:Observer Variation; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal