title: Comparison of gestational sac volume by 3D-sonography using planimetric, virtual organ computer-aided analysis and extended imaging virtual organ computer-aided analysis methods between 7 and 11 weeks of pregnancy.
abstract: OBJECTIVE
  To compare different three-dimensional (3D) methods in the assessment of gestational sac volume (GSV).
  
  
  METHODS
  Cross-sectional study involving 74 normal pregnancies between 7 and 11 weeks.
  
  
  METHODS
  Department of Obstetrics, São Paulo Federal University (UNIFESP).
  
  
  METHODS
  GSV was measured through 3D ultrasound using the planimetric, virtual organ computer-aided analysis (VOCAL) and extended imaging virtual organ computer-aided analysis (XI VOCAL) methods. The planimetric method used a sequence of adjacent planes that are 3 mm thick. For the VOCAL methods, six adjacent planes and a 30 degrees rotation were used. A total of 15 adjacent planes were used for the XI VOCAL method. Regression models with a determination coefficient (R(2)) were created to assess the correlation between GSV and gestational age (GA). Intraclass correlation coefficient (ICC) and Bland-Altman graphs were used to assess the correlation between the three methods and ANOVA was used to compare means.
  
  
  RESULTS
  All three methods showed a correlation between GSV and GA (R(2) = 0.65 for XI VOCAL, R(2) = 0.65 for planimetric and R(2) = 0.66 for VOCAL). There was a strong correlation between the three methods (XI VOCAL vs. planimetric ICC = 0.995; XI VOCAL vs. VOCAL ICC = 0.998 and planimetric vs. VOCAL ICC = 0.995) without any significant differences according to the Bland-Altman graphs or ANOVA (p < 0.002).
  
  
  CONCLUSIONS
  The three 3D ultrasound methods used for GSV assessment between 7 and 11 weeks are concordant. These methods can be used interchangeably during the first trimester of pregnancy to measure GSV.
authors.affiliation: Department of Obstetrics, São Paulo Federal University , São Paulo, SP, Brazil.
authors.forename: Luciano Marcondes Machado
authors.initials: LM
authors.lastname: Nardozza
authors.forename: Liliam Cristine
authors.initials: LC
authors.lastname: Rolo
authors.forename: Edward
authors.initials: E
authors.lastname: Araujo Júnior
authors.forename: Paulo Martin
authors.initials: PM
authors.lastname: Nowak
authors.forename: João Bortoletti
authors.initials: JB
authors.lastname: Filho
authors.forename: Antonio Fernandes
authors.initials: AF
authors.lastname: Moron
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003430:Cross-Sectional Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012044:Regression Analysis; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014584:User-Computer Interface