title: Agreement and reliability of pelvic floor measurements during contraction using three-dimensional pelvic floor ultrasound and virtual reality.
abstract: OBJECTIVE
  Virtual reality is a novel method of visualizing ultrasound data with the perception of depth and offers possibilities for measuring non-planar structures. The levator ani hiatus has both convex and concave aspects. The aim of this study was to compare levator ani hiatus volume measurements obtained with conventional three-dimensional (3D) ultrasound and with a virtual reality measurement technique and to establish their reliability and agreement.
  
  
  METHODS
  100 symptomatic patients visiting a tertiary pelvic floor clinic with a normal intact levator ani muscle diagnosed on translabial ultrasound were selected. Datasets were analyzed using a rendered volume with a slice thickness of 1.5 cm at the level of minimal hiatal dimensions during contraction. The levator area (in cm(2)) was measured and multiplied by 1.5 to get the levator ani hiatus volume in conventional 3D ultrasound (in cm(3)). Levator ani hiatus volume measurements were then measured semi-automatically in virtual reality (cm(3) ) using a segmentation algorithm. An intra- and interobserver analysis of reliability and agreement was performed in 20 randomly chosen patients.
  
  
  RESULTS
  The mean difference between levator ani hiatus volume measurements performed using conventional 3D ultrasound and virtual reality was 0.10 (95% CI, - 0.15 to 0.35) cm(3). The intraclass correlation coefficient (ICC) comparing conventional 3D ultrasound with virtual reality measurements was > 0.96. Intra- and interobserver ICCs for conventional 3D ultrasound measurements were > 0.94 and for virtual reality measurements were > 0.97, indicating good reliability for both.
  
  
  CONCLUSIONS
  Levator ani hiatus volume measurements performed using virtual reality were reliable and the results were similar to those obtained with conventional 3D ultrasonography.
authors: Department of Obstetrics and Gynecology, Division of Obstetrics and Prenatal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands.
authors: L
authors: L
authors: Speksnijder
authors: M
authors: M
authors: Rousian
authors: E A P
authors: EA
authors: Steegers
authors: P J
authors: PJ
authors: Van Der Spek
authors: A H J
authors: AH
authors: Koning
authors: A B
authors: AB
authors: Steensma
mesh_terms: D003198:Computer Simulation; D003362:Cost-Benefit Analysis; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D009119:Muscle Contraction; D017773:Pelvic Floor / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D056887:Pelvic Organ Prolapse / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D010502:Perineum / Q000000981:diagnostic imaging* / Q000473:pathology; D015203:Reproducibility of Results; D014463:Ultrasonography; D014584:User-Computer Interface; D014590:Uterine Contraction; D014636:Valsalva Maneuver