The aim of our study was to evaluate the first trimester cerebellar growth and development using 2 different measuring techniques: 3-dimensional (3D) and virtual reality (VR) ultrasound visualization. The cerebellum measurements were related to gestational age (GA) and crown-rump length (CRL). Finally, the reproducibility of both the methods was tested. In a prospective cohort study, we collected 630 first trimester, serially obtained, 3D ultrasound scans of 112 uncomplicated pregnancies between 7 + 0 and 12 + 6 weeks of GA. Only scans with high-quality images of the fossa posterior were selected for the analysis. Measurements were performed offline in the coronal plane using 3D (4D view) and VR (V-Scope) software. The VR enables the observer to use all available dimensions in a data set by visualizing the volume as a "hologram." Total cerebellar diameter, left, and right hemispheric diameter, and thickness were measured using both the techniques. All measurements were performed 3 times and means were used in repeated measurements analysis. After exclusion criteria were applied 177 (28%) 3D data sets were available for further analysis. The median GA was 10 + 0 weeks and the median CRL was 31.4 mm (range: 5.2-79.0 mm). The cerebellar parameters could be measured from 7 gestational weeks onward. The total cerebellar diameter increased from 2.2 mm at 7 weeks of GA to 13.9 mm at 12 weeks of GA using VR and from 2.2 to 13.8 mm using 3D ultrasound. The reproducibility, established in a subset of 35 data sets, resulted in intraclass correlation coefficient values ≥0.98. It can be concluded that cerebellar measurements performed by the 2 methods proved to be reproducible and comparable with each other. However, VR-using all three dimensions-provides a superior method for the visualization of the cerebellum. The constructed reference values can be used to study normal and abnormal cerebellar growth and development.
Keywords: 3D ultrasound; 4D view; cerebellum; first trimester; virtual reality.