Evaluation of the ratio of the transverse diameter of cerebellum to the transverse diameter of frontal lobe by trans-cerebellar section

Abstract Objective On the basis of a prospective study of evaluating the development of frontal lobe in mid-to-late trimester by trans-cerebellar section, it had been found that the transverse frontal diameter had a higher correlation with gestational age than the anteroposterior frontal diameter. In order to provide more valuable information for the prenatal diagnosis of suspected fetal microcephaly, the reference value range of the ratio of the transverse diameter of cerebellum to the transverse diameter of frontal lobe by trans-cerebellar section was further prospectively established. Methods A prospective cross-sectional study was conducted on 870 normal fetuses at 21 to 36 weeks of gestation from January 2019 to June 2020. The transverse diameter of cerebellum and the transverse diameter of frontal lobe were measured by trans-cerebellar section, and the ratio of the transverse diameter of cerebellum to the transverse diameter of frontal lobe was calculated, and the correlation was analyzed statistically. Results The ratio of the transverse diameter of cerebellum to the transverse diameter of frontal lobe increased positively with gestational age which correlation coefficient was 0.413 (P < 0.001). Taking gestational age as the independent variable and the ratio of the transverse diameter of cerebellum to the transverse diameter of frontal lobe as the dependent variable, it showed that there was a linear relationship between the gestational age and the ratio of the transverse diameter of cerebellum to the transverse diameter of frontal lobe. We got a correlation formula that the ratio of the transverse diameter of cerebellum to the transverse diameter of frontal lobe =0.004× (gestational age-21)+0.530. Conclusion This study has preliminarily established the normal reference range of the ratio of the transverse diameter of cerebellum to the transverse diameter of frontal lobe by trans-cerebellar section in normal mid-to-late pregnancy fetuses, which can provide valuable information for the prenatal diagnosis of suspected fetal microcephaly.