Transvaginal Three-dimensional Sonographic Assessment of the Embryonic Brain: A Pilot Study

Abstract

AimsA very good knowledge of human embryology is mandatory not only for the correct sonographic assessment of the developing brain, but also for better understanding the origins of congenital anomalies involving the central nervous system. 3D transvaginal sonography may be an effective technique for imaging the developing brain. The aims of this explorative study are to demonstrate the feasibility of imaging the embryonic brain between 7 and 10 weeks of gestation for clinical studies by using a 3D high-frequency vaginal ultrasound transducer and to provide a reference for the morphology of the brain in the embryonic period.Materials and methodsFour embryos of 9 mm, 17 mm, 23 mm and 31 mm crown-rump length respectively were assessed in vivo by transvaginal sonography. We gave a special attention to the embryonic brain. All patients were examined with a Voluson E10, BT 15 ultrasound scanner (GE Healthcare, Zipf, Austria), using a high-frequency 6–12 MHz/ 256-element 3D/4D transvaginal transducer. Three-dimensional sonography was performed routinely as the patients were scanned. The multiplanar display was used after selecting the best volume. The Omni view® software was used for digitally slicing the selected volumes.ResultsWe describe the morphological details of the developing brains of four embryos ranging from 7 to 10 gestational weeks. In the human embryo 9 mm CRL the hypoechogenic cavities of the three primary vesicles (prosencephalon, mesencephalon, rhombencephalon) could be observed on a sagittal section. In the human embryo 17 mm CRL the prosencephalon was divided into the median diencephalon and two telencephalic vesicles, which were partially separated by the falx cerebri. In the human embryo 23 mm CRL the cerebral hemispheres developed and they were completely separated by the falx cerebri. The choroid plexus was evident inside the lateral ventricles and the fourth ventricle. In the human embryo 31 mm CRL the ventral thalamus was evident, and the ganglionic eminence, as the precursor of the basal ganglia, was well seen on the floor of the cerebral hemispheres.ConclusionsStudies of embryology are still needed for a complete understanding of the developing brain. 3D sonography using a high-frequency vaginal ultrasound transducer is feasible for imaging the embryonic brain with an acceptable quality for clinical studies.

Ultrasound visualization of the central nervous system during embryonic and fetal periods: Neurosonoembryology utilizing multiple three‐dimensional transvaginal ultrasound technology

“…While some scholars have reported that the cerebellum and the 4th VCP can be seen at 8 weeks of menstrual age, 19,20 Boitor-Borza et alfound that only the metencephalon and the myelencephalon were visible at 8 weeks (with a CRL of 17 mm). 17 The novel finding of this study is that the orientation of the 4th VCP appears to change from being perpendicular to the long axis of the neural tube to being parallel to it in fetuses measuring 41-84 mm CRL, as observed from the mid-sagittal view. This discovery is in agreement with the embryological images published by Bayer and other embryologists, 12 indicating that the high-resolution ultrasound imaging findings correlated well with the anatomy of solid specimens.…”

“…utilized the OmniView software and reported that embryos with a CRL of 9 mm only exhibit a relatively simple anatomical brain structure. Specifically, they were only able to identify the forebrain, midbrain, and rhombencephalon 17 . In our study, we discovered that using high‐resolution transvaginal 3D sonography, the structure of the prosencephalon, mesencephalon, and rhombencephalon can be clearly visualized in embryos with a CRL of 10–15 mm.…”

“…Specifically, they were only able to identify the forebrain, midbrain, and rhombencephalon. 17 In our study, we discovered that using high-resolution transvaginal 3D sonography, the structure of the prosencephalon, mesencephalon, and rhombencephalon can be clearly visualized in embryos with a CRL of 10-15 mm. We observed that the lateral ventricles, the future third ventricle, and the foramen of Monro develop from the prosencephalon.…”

“…However, the gestational weeks of hindbrain embryo development remain a controversial topic. While some scholars have reported that the cerebellum and the 4th VCP can be seen at 8 weeks of menstrual age, 19,20 Boitor‐Borza et al.found that only the metencephalon and the myelencephalon were visible at 8 weeks (with a CRL of 17 mm) 17 . We found that the cerebellar primordium begins to form in embryos measuring 16–22 mm CRL, and the developing cerebellum, the fourth ventricle, and the 4th VCP can be seen in embryos measuring 23–30 mm CRL.…”