Gestational sac volume by 3D-sonography at 7–10 weeks of pregnancy using the VOCAL method

Gestational sac fluid volume measurements in virtual reality

OBJECTIVES

To evaluate a virtual reality (VR) application for gestational sac fluid volume (GSFV) measurements in first-trimester pregnancies and to study the correlation between different embryonic growth parameters.

METHODS

This was a prospective cohort study analyzing 180 three-dimensional (3D) ultrasound scans of 42 healthy women, performed between 5 + 5 and 12 + 6 weeks' gestational age (GA). The 3D datasets were transferred to the I-Space immersive VR system. The V-Scope application was used to create a 'hologram' of the ultrasound image, allowing depth perception and interaction with the rendered objects. Volumes were measured semi-automatically using a segmentation algorithm. In addition to the GSFV, the total gestational sac volume (GSV) and its diameter (GSD) were measured. The GSV was also calculated using the ellipsoid formula. Previously obtained measurements of embryonic volume and crown-rump length (CRL) were included in the study. The outcomes were analyzed using repeated-measures analysis of variance.

RESULTS

The GSFV was measured in 78 scans, and varied from 434 to 81 491 mm(3). A positive correlation between GSFV and GA, CRL and GSD was found. Comparison of the GSD formula constructed in our study in relation to GA with a formula that is commonly used clinically showed an increasing difference with increasing GA either side of 8 + 5 weeks. The GSFV/embryonic volume ratio showed a decrease with GA. The GSV calculated using the ellipsoid formula was on average 19.8% larger compared with the GSV measured in VR.

CONCLUSION

New charts for first-trimester GSFV were constructed using VR. These growth charts could be promising tools for studying normal and abnormal embryonic development.

First trimester 3D volumetry. Association of the gestational volumes with the birth weight

OBJECTIVE

To evaluate the three dimensional ultrasound (3D) in the volume assessment of the gestational contents during the 1st trimester of pregnancy. Our aim was to correlate the embryo, gestational sac, and placenta volume with the birth weight. To monitor the increase of these volumes according to the gestational age.

METHOD

Prospective study of 199 singleton low risk pregnant women undergoing the 1st trimester ultrasound for fetal anomalies. In these women, gestational volumetry was performed and it was compared with the crown-rump length (CRL). Regression models were computed in order to analyze the dependence of birth weight with the volumes.

RESULTS

The embryo volume reveals the strongest association with the birth weight at delivery (β = 0.24), followed by the CRL (β = 0.20) and the gestational sac volume (β = 0.20). The placenta volume appears the weakest association with fetal weight at delivery (β = 0.16). All volumes increased significantly from 11(+0)-11(+6) to 13(+0)-13(+6) weeks of gestation (p < 0.001). Ten cubic millimeter increase in embryo volume corresponds to a mean birth weight increase of 75 g, while 1 mm increase in the CRL corresponds to a birth weight increase of 113 g.

CONCLUSION

Our results provide evidence that the embryo volume during the first trimester of pregnancy correlates better with birth weight than the CRL. This might assist in the identification of the high risk pregnancies caring macrosomic and low birth weight fetuses.

First trimester ultrasound: current approaches and practical pitfalls

Revolutionary technological improvements and high-frequency transvaginal scanning have enabled the resolution of ultrasound imaging in the first trimester to increase such that detailed early fetal development can now be well visualized. This investment in imaging technology has enabled not only normal embryonic development but also chromosomal abnormalities and structural anomalies to be more easily and accurately diagnosed before the second trimester. This article is intended to help radiologists in the interpretation and clinical application of normal and abnormal first trimester ultrasound findings in early pregnancy. We review the current literature and applications and interpretations of first trimester ultrasound.