title: Real-time three-dimensional ultrasound with Live xPlane imaging assists first-trimester acquisition of a true midsagittal section.
abstract: OBJECTIVE
  To determine whether real-time three-dimensional (3D) ultrasound with Live xPlane imaging, which enables the simultaneous display of two real-time high-quality image planes, can assist both operators certified by The Fetal Medicine Foundation (FMF) and non-FMF-certified operators in acquiring a true midsagittal plane in the first trimester.
  
  
  METHODS
  Eight operators, four of them FMF certified (FMF group) and the other four not (non-FMF group), were asked to acquire a fetal image that they believed to represent the true midsagittal plane using real-time 3D ultrasound with Live xPlane imaging as guidance. Each operator was asked to obtain such an image five times from each of five patients. A total of 200 images from 40 patients were obtained and stored for subsequent analysis. All pregnancies were between 11 + 0 and 13 + 6 weeks of gestation. The angle between the falx cerebri and vertical axis (angle of deviation) was then measured by a single operator. A true midsagittal section was defined as an angle of deviation equal to 0 degrees. The angle of deviation and the time taken to acquire each image were compared between FMF and non-FMF groups.
  
  
  RESULTS
  The median angle of deviation for each operator ranged from 1.2 degrees to 3.4 degrees. There was no significant difference in this angle between those who were FMF certified and those who were not (2.0 degrees vs. 2.2 degrees, P = 0.463). The interquartile range of the angle of deviation was also similar between the FMF- and non-FMF-certified operators. Although the time taken for image acquisition was longer among the non-FMF-certified operators (median, 45.5 s vs. 32.0 s), this difference did not reach statistical significance (P = 0.107).
  
  
  CONCLUSIONS
  Live xPlane imaging can provide a tool to assist the acquisition of a true midsagittal plane and to determine how true a 'midsagittal' plane really is.
authors.affiliation: Fetal Medicine Unit, Department of Obstetrics and Gynaecology, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China. xiongyi.xiongyi@163.com
authors.forename: Y
authors.initials: Y
authors.lastname: Xiong
authors.forename: Y M I
authors.initials: YM
authors.lastname: Wah
authors.forename: L W
authors.initials: LW
authors.lastname: Chan
authors.forename: T Y
authors.initials: TY
authors.lastname: Leung
authors.forename: T Y
authors.initials: TY
authors.lastname: Fung
authors.forename: T K
authors.initials: TK
authors.lastname: Lau
mesh_terms: D002531:Cerebellum / Q000000981:diagnostic imaging* / Q000196:embryology; D002983:Clinical Competence / Q000592:standards*; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D005865:Gestational Age; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D048208:Nuchal Translucency Measurement / Q000592:standards*; D015588:Observer Variation; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D016216:Ultrasonography, Prenatal / Q000379:methods