title: Design and validation of a 3D virtual reality desktop system for sonographic length and volume measurements in early pregnancy evaluation.
abstract: OBJECTIVE
  To design and validate a desktop virtual reality (VR) system, for presentation and assessment of volumetric data, based on commercially off-the-shelf hardware as an alternative to a fully immersive CAVE-like I-Space VR system.
  
  
  METHODS
  We designed a desktop VR system, using a three-dimensional (3D) monitor and a six degrees-of-freedom tracking system. A personal computer uses the V-Scope (Erasmus MC, Rotterdam, The Netherlands) volume-rendering application, developed for the I-Space, to create a hologram of volumetric data. Inter- and intraobserver reliability for crown-rump length and embryonic volume measurements are investigated using Bland-Altman plots and intraclass correlation coefficients. Time required for the measurements was recorded.
  
  
  RESULTS
  Comparing the I-Space and the desktop VR system, the mean difference for crown-rump length is -0.34% (limits of agreement -2.58-1.89, ±2.24%) and for embryonic volume -0.92% (limits of agreement -6.97-5.13, ±6.05%). Intra- and interobserver intraclass correlation coefficients of the desktop VR system were all >0.99. Measurement times were longer on the desktop VR system compared with the I-Space, but the differences were not statistically significant.
  
  
  CONCLUSIONS
  A user-friendly desktop VR system can be put together using commercially off-the-shelf hardware at an acceptable price. This system provides a valid and reliable method for embryonic length and volume measurements and can be used in clinical practice.
authors.affiliation: Department of Obstetrics and Gynaecology, Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Center Rotterdam, Room Na15.23, PO Box 2040, 3000, CA Rotterdam, The Netherlands.
authors.forename: Leonie
authors.initials: L
authors.lastname: Baken
authors.forename: Isabelle M A
authors.initials: IM
authors.lastname: van Gruting
authors.forename: Eric A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: Peter J
authors.initials: PJ
authors.lastname: van der Spek
authors.forename: Niek
authors.initials: N
authors.lastname: Exalto
authors.forename: Anton H J
authors.initials: AH
authors.lastname: Koning
mesh_terms: D049628:Body Size; D018568:Crown-Rump Length; D005260:Female; D005333:Fetus / Q000033:anatomy & histology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D015588:Observer Variation; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal; D014584:User-Computer Interface
keywords: image processing; reproducibility; three-dimensional ultrasound; virtual reality; volume measurement