Fetal cerebellar development: 3D morphometric analysis of fetal postmortem MRI among Chinese fetuses

Abstract

The development of the cerebellum starts from early gestational period and extends postnatal. Because of its protracted development, the cerebellum is susceptible to developmental anomalies such as Dandy-Walker malformations, Blakes pouch cysts and vermin hypoplasia. Measurements of fetal cerebellar parameters of a normal growing fetus in each week of gestation is important for setting up morphometric standards and hence used as clinical reference data. Any deviation from the normal cerebellar parameters alerts the clinicians for the possibility of presence of cerebellar malformations. Study objective: The objective of this study was to assess the fetal cerebellar growth by quantifying the following parameters; fetal cerebellar volume, anterior-posterior diameter and superior-inferior diameter. Methods: We used 3T and 7T MRI to scan the postmortem fetal brains at different stages of development and subsequently analyze the images using ITK-SNAP software. Results: The mean superior-inferior cerebellar diameter was found to be 19.12+2. 70mm.The linear(y=bo+b1t) model was the best fit (r2=0.996, F=32022.961) to describe the relationship between the gestational age and the superior-inferior diameter(y=5.89+0.49t). There was significant correlation between the superior-inferior cerebellar diameter and the gestation age, Pearson correlation coefficient of 0.999, r=0.001. The median cerebellar volume was 8607.7mm, the mean rank high among males(78.12) as compared to female(68.25). There was no statistically significant difference of the cerebellar volume between males and females (u=2193.5,p=0.16). The quadratic(y=bo+b1t+b2t2) model was the best fit regression equation (r2=0.994,F=10791.157) describing the relationship between the cerebellar volume and the gestational age. The median anterior-posterior diameter was 12.45 mm. There was significant correlation between anterior-posterior diameter and the gestational age with Spearmans rho of (0.997, p=0.01). The linear model was the best fit the best fit model (y=bo+b1t) describing the relationship between anterior-posterior diameter and the gestational age(y=3.31+0.5t) r2=0.998, F=70646.838. Conclusion: Significant correlation between the superior-inferior cerebellar diameters, the anterior-posterior cerebellar diameter and the gestational age was found. These two linear parameters follow the first-degree polynomial in relation to the gestational age. The cerebellar volume follows the second-degree polynomial as it increases with the gestational age and correlate significantly with the gestational age. This study has provided new insight to the development of the cerebellum, and setup a benchmark data of which the deviation from it will alert the clinicians for the possibility of presence of cerebellar malformations. Key words: Cerebellar Development, Cranial Magnetic Resonance imaging, Cerebellar Malformations