title: Three-dimensional ultrasound fetal lung volume measurement: a systematic study comparing the multiplanar method with the rotational (VOCAL) technique.
abstract: OBJECTIVE
  This study was designed to compare a conventional multiplanar technique for three-dimensional (3D) ultrasound measurement of fetal lung volume with a rotational method using VOCAL trade mark (Virtual Organ Computer-aided AnaLysis).
  
  
  METHODS
  Thirty-two fetuses with a variety of conditions at risk for pulmonary hypoplasia were studied. 3D volume data sets of the fetal lungs were acquired using a commercially available ultrasound system. The right and left lung volumes were calculated separately using VOCAL and the multiplanar technique. The level of agreement between two independent observers in categorizing the 3D volume data set as measurable or non-measurable was determined. The interobserver and intermethod variabilities were also evaluated for both methods.
  
  
  RESULTS
  The intermethod variability was excellent (correlation r = 0.93 and r = 0.96 for the left and right lung, respectively), and there was substantial agreement between the results of both approaches (limits of agreement - 4.4 to 8.9 and - 3.4 to 4.8 mL for the right and left lung, respectively). Fetal lung estimation with VOCAL had a significantly higher interobserver variability than the multiplanar technique. Interobserver agreement in categorizing lung volume data sets as measurable or non-measurable was lower when VOCAL was used.
  
  
  CONCLUSIONS
  Fetal lung volume measurements can be undertaken interchangeably using the multiplanar technique or the rotational method with VOCAL. However, the latter was less reproducible (lower degree of agreement and significantly higher interobserver variability) than the former.
authors.affiliation: Perinatology Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, DHHS, Bethesda, MD, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Kalache
authors.forename: J
authors.initials: J
authors.lastname: Espinoza
authors.forename: T
authors.initials: T
authors.lastname: Chaiworapongsa
authors.forename: J
authors.initials: J
authors.lastname: Londono
authors.forename: M L
authors.initials: ML
authors.lastname: Schoen
authors.forename: M C
authors.initials: MC
authors.lastname: Treadwell
authors.forename: W
authors.initials: W
authors.lastname: Lee
authors.forename: R
authors.initials: R
authors.lastname: Romero
mesh_terms: D005260:Female; D005865:Gestational Age; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008168:Lung / Q000002:abnormalities / Q000000981:diagnostic imaging / Q000196:embryology*; D008176:Lung Volume Measurements / Q000379:methods; D015588:Observer Variation; D011247:Pregnancy; D012044:Regression Analysis; D016216:Ultrasonography, Prenatal / Q000379:methods*