First trimester brain ventricle fluid and embryonic volumes measured by three-dimensional ultrasound with the use of I-Space virtual reality.

STUDY QUESTION Is it possible to evaluate first trimester brain ventricle development in human pregnancies using an innovative virtual reality (VR) application and to analyze the relation of the embryonic volume (EV) and brain ventricle fluid volume (BVFV) with gestational age (GA), crown-rump length (CRL) and the Carnegie stage? SUMMARY ANSWER Volumetry and staging of the human embryo using a VR application make it possible to obtain unique information about in-vivo embryonic normal and abnormal development and about the sizes of the ventricles and body. WHAT IS KNOWN ALREADY Human brain development is complex and has a rapidly changing anatomy during the first trimester of pregnancy. New insights will enable early detection of cerebral pathology. STUDY DESIGN, SIZE, DURATION In a prospective cohort study, we weekly performed three-dimensional (3D) ultrasound examinations in 112 uncomplicated pregnancies between 6 + 0 and 12 + 6 weeks GA. MATERIALS, SETTING, METHODS The examinations resulted in 696 3D ultrasound scans that were transferred to the I-Space VR system and analyzed using V-Scope volume rendering software. V-Scope is used to create a 'hologram' of the ultrasound image and allows depth perception and interaction with the rendered objects. The CRL measurements were performed with a tracing tool, and the volume measurements were automatically performed with a segmentation algorithm. The embryos were staged according to the internal and external characteristics of the Carnegie staging system. All longitudinal outcomes were analyzed using repeated measures ANOVA. MAIN RESULTS AND THE ROLE OF CHANCE CRL could be measured in 91% of the datasets and ranged from 2.5 to 79.0 mm. EV could be measured in 66% of the datasets and ranged from 2.4 to 23 812.0 mm³, whereas the BVFV could be measured in 38% of the datasets and ranged from 10.4 to 226.3 mm³. Finally, in 74% of the datasets, the embryos were staged according to the Carnegie criteria, starting as early as stage 12. Reference charts of volumes versus GA, CRL and stage were constructed. There was no significant relationship between the CRL or EV and the birthweight. LIMITATIONS, REASONS FOR CAUTIONS The low success rate is a limitation of this study that can be explained mainly by non-targeted scanning of the embryonic head. WIDER IMPLICATIONS OF THE FINDINGS The I-Space VR system and the V-Scope software enable automatic EV and BVFV measurements and 3D observations of embryonic development in the first trimester. This allows in-vivo staging of human embryos based on both internal and external morphological characteristics. STUDY FUNDING, COMPETING INTERESTS None.