OC16.05: First trimester human yolk sac and fetal volumetry in virtual reality

Abstract

Objective: The aim of this study was to evaluate real-time three dimensional (3D) determined volumes of the yolk sac and fetal body, including the limbs, in first trimester pregnancies using a virtual reality (VR) application, and to analyse relations with gestational age (GA) and crown-rump length (CRL). Methods: We analyzed 180 3D first trimester ultrasound scans of 42 spontaneous and IVF/ICSI pregnancies. Only scans with high quality images were included and transferred to a Barco ISpace VR system and visualized as 3D ‘holograms’ with V-Scope volume rendering software. An implemented segmentation algorithm calculated the yolk sac volume (YSV) and fetal volume (FV) semiautomatically (A). The logarithmically transformed outcomes were analyzed using repeated measurements ANOVA. Interobserver agreement was established by calculating intraclass correlation coefficients (ICC). Results: In total 118 YSV and 88 FV were measured with GA between 5 + 5 and 12 + 6 weeks. YSV ranged from 33 mm3 to 424 mm3 and FV ranged from 14 mm3 to 29877 mm3. Reference charts were constructed according to GA and CRL (B). ANOVA calculations showed that when the CRL doubles, the mean FV increases 6.5 fold and when the GA doubles the mean FV increases approximately 500 fold (p<0.001). Furthermore, it was found that for each day, the YSV increases on average by 4% and when the CRL doubles, the YSV increases with 67% (p<0.001). Interobserver agreement was excellent with an ICC of 0.99. Conclusions: We constructed reference charts for growth of YSV and FV in the first trimester using a VR system. This approach allows us to obtain information about the size of the fetus using all dimensions. These new data can be used to differentiate between normal and abnormal human development.