Dynamics of the size ratio between the cerebellar vermis and the fourth ventricle of the human brain during the fetal period of ontogenesis.

Abstract

Objective: Aim: To determine the patterns of change in the cross-sectional area of the cerebellar vermis and the fourth ventricle during the fetal period of human ontogenesis and to analyze the dynamics of their interrelationship.

Patients and methods: Materials and Methods: The study was conducted using magnetic resonance imaging (MRI) scans of the human fetal brain obtained from open-access databases. Generalized images from the "Fetal Brain Atlas" (21-38 weeks of gestation) and MRI scans from the "Fetal Brain MRI from Stanford Lucile Packard Children's Hospital" database (20-39 weeks of gestation, n=20) were used. Morphometric analysis of mid-sagittal sections was performed using the Image Tool software. The cross-sectional areas of the cerebellar vermis and the fourth ventricle were measured, along with their relative values and ratios.

Results: Results: Between 21 and 38 weeks of gestation, the cross-sectional area of the cerebellar vermis increased steadily, whereas the fourth ventricle exhibited a biphasic growth pattern: relatively slow expansion until 30 weeks, followed by accelerated growth. The analysis of relative areas revealed that the growth rate of the cerebellum exceeded that of the fourth ventricle until 30-32 weeks, after which the fourth ventricle underwent rapid expansion, leading to an alignment of their relative values. The ratio of the fourth ventricle's area to that of the cerebellum ranged from 4.8% to 9.8%, showing minimal values at 25-28 weeks and rapid growth between 28 and 34 weeks of gestation.

Conclusion: Conclusions: The obtained data indicate changes in the proportional relationship between the cerebellum and the fourth ventricle throughout the fetal period of ontogenesis, reflecting the specific features of their morphogenesis. The proposed approach for assessing the interrelationship between these structures may be useful for analyzing both normal and abnormal hindbrain development during the prenatal period.