Early second‐trimester three‐dimensional transvaginal neurosonography of fetal midbrain and hindbrain: normative data and technical aspects

• Published in: Ultrasound in obstetrics & gynecology 2022-03, Vol.59 (3), p.317-324
• Main Authors: Birnbaum, R., Barzilay, R., Brusilov, M., Acharya, P., Malinger, G., Krajden Haratz, K.
• Format: Article
• Language: English
• Subjects: Age; Blake's pouch cyst; Brain; Brain stem; brainstem kinking; cerebellar vermis; Cerebellum; cerebral aqueduct of Sylvius; Choroid plexus; Cracks; Cranial Fossa, Posterior - diagnostic imaging; Diameters; Dimensional analysis; early neurosonography; Female; fetal brain; Fetuses; Fourth Ventricle - diagnostic imaging; Gestational Age; Gynecology; Hindbrain; Humans; Infant; Menstruation; Mesencephalon; Mesencephalon - diagnostic imaging; midbrain–hindbrain; Obstetrics; posterior fossa; Pregnancy; Pregnancy Trimester, Second; Retrospective Studies; Rhombencephalon - diagnostic imaging; Thickness; Transducers; Ultrasonic imaging; Ultrasonography, Prenatal - methods; Ventricle
• ISSN: 0960-7692; 1469-0705
• DOI: 10.1002/uog.23691

ABSTRACT Objectives To provide a detailed description of the sonographic appearance and development of various fetal structures of the midbrain and hindbrain (MBHB) during the early second trimester, and to evaluate the impact of the frequency of the transvaginal sonography (TVS) transducer on the early recognition of these structures. Methods This was a retrospective analysis of three‐dimensional volumetric datasets of the MBHB from apparently normal fetuses at 14–19 gestational weeks, acquired by TVS in the midsagittal view through the posterior fontanelle. Using a multiplanar approach, we measured the tectal thickness and length, aqueductal thickness, tegmental thickness and width and height of the Blake's pouch (BP) neck. In addition, we assessed the existence of early vermian fissures, the linear shape of the brainstem and the components of the fastigium. The correlation between gestational age according to last menstrual period and sonographic measurements of MBHB structures was evaluated using Pearson's correlation (r). A subanalysis was performed to assess the performance of a 5–9‐MHz vs a 6–12‐MHz TVS transducer in visualizing the MBHB structures in the early second trimester. Results Sixty brain volumes were included in the study, obtained at a mean gestational age of 16.2 weeks (range, 14.1–19.0 weeks), with a transverse cerebellar diameter range of 13.0–19.8 mm. We found a strong correlation between gestational age and all MBHB measurements, with the exception of the tectal, tegmental and aqueductal thicknesses, for which the correlation was moderate. There was good‐to‐excellent intraobserver and moderate‐to‐good interobserver correlation for most MBHB measurements. We observed that the BP neck was patent in all fetuses between 14 and 18 weeks with decreasing diameter, and that the aqueductal thickness was significantly smaller at ≥ 18 weeks compared with at