Objective On the basis of retrospectively analysis the trans-cerebellar section showing the Sylvian fissure of normal fetus is better than trans-thalamic section in middle and late trimester, we prospectively established the normal reference range of developmental parameters related to the Sylvian fissure of normal fetus in the trans-cerebellar section in order to provide valuable information for the diagnosis of fetal cerebral cortical dysplasia. Methods A prospective cross-sectional study was conducted on 845 normal fetuses at 21 to 32 weeks of gestation from January 2019 to September 2020. The depth and width of the Sylvian fissure was measured respectively, and regression analysis was performed according to different gestational age groups. Results The depth of Sylvian fissure was positively correlated with gestational weeks, and the width of Sylvian fissure was negatively correlated with gestational weeks, with correlation coefficients 0.751 and 0.825 respectively (all P < 0.001).Taking gestational weeks as the independent variable, and the depth and width of Sylvian fissure of fetus as the dependent variables, linear regression analysis showed that there was a linear relationship between the independent variables and the dependent variables. The obtained equation was simplified to a formula: Fetal Sylvian fissure depth (mm)=7+0.6X(gestational weeks-21), Sylvian fissure width (mm)=8-0.6X(gestational weeks-21). Conclusion The reference range of the depth and width of Sylvian fissure of normal fetus at 21 to 32 weeks of pregnancy through the trans-cerebellar section was established, which could provide valuable information for the evaluation of the normal development of the lateral fissure of fetus and the prenatal diagnosis of fetal cortical hypoplasia. Key words Fetus; Sylvian fissure; depth; width; trans-cerebellar section

ObjectiveTo compare the clearness rate of fetal Sylvian fissure revealed by prenatal ultrasonography on trans-cerebellar section and trans-thalamic section, and to provide scientific basis for selecting the best section of prenatal ultrasound to evaluate the developmental parameters related to fetal Sylvian fissure.MethodsThis was a retrospective study. We analyzed all the fetal images on trans-cerebellar section and trans-thalamic section stored in the imaging system who were undergoing grade III prenatal ultrasound examination in our hospital from January 2017 to December 2018. The gestational age was divided into three groups which were 21 to 24 weeks, 25 to 28 weeks and 29 to 32 weeks respectively. The evaluation criteria for the clear appearance of the Sylvian fissure were complete morphology of the Sylvian fissure and clear apical and anteriorly edges of the Sylvian fissure. The results of showing Sylvian fissure clearly were divided into four groups: only on trans-cerebellar section shown clear, only on trans-thalamic section shown clear, both on trans-cerebellar section and trans-thalamic section shown clear, and both on trans-cerebellar section and trans-thalamic section not shown clear. The clearness rate of each group and the total clearness rate of each section were analyzed statistically.ResultsThe clearness rates of showing Sylvian fissure only on trans-cerebellar section were 62.3% at 21 to 24 weeks, 70.1% at 25 to 28 weeks and 63.6% at 29 to 32 weeks. The clearness rates of showing Sylvian fissure only on trans-thalamic section were 11.1% at 21 ∼ 24 weeks, 10.5% at 25 ∼ 28 weeks and 9.1% at 29 ∼ 32 weeks. The clearness rates of showing Sylvian fissure both on trans-cerebellar and trans-thalamic sections were 22.1% at 21 to 24 weeks, 15.0% at 25 to 28 weeks and 13.0% at 29 to 32 weeks. The unclearness rates of showing Sylvian fissure both on trans-cerebellar and trans-thalamic sections were 4.5%at 21 ∼ 24 weeks, 4.4% at 25 ∼ 28 weeks and 14.3% at 29 ∼ 32 weeks. The clearness rate of showing Sylvian fissure on trans-cerebellar section was significantly higher than on trans-thalamic section (P < 0.05). The total clearness rate of showing Sylvian fissure on trans-cerebellar section and trans-thalamic section were 83.1% and 28.3% respectively.ConclusionIn this study, it was suggested that prenatal ultrasound selection of trans-cerebellar section is better than trans-thalamic section in evaluating the developmental parameters related to the Sylvian fissure.

ObjectiveTo establish a reference range of developmental parameters related to the frontal lobe of normal fetuses in different gestational weeks, which can provide a basis for the evaluation of normal development of the frontal lobe and the diagnosis of suspected fetal microcephaly.MethodsA prospective cross-sectional study was performed on 751 normal fetuses between 21 and 36 weeks, and the anterior-posterior diameter and transverse diameter of the frontal lobe were measured in transcerebellar plane. Linear regression analysis was performed by grouping different gestational weeks.ResultsFetal anterior-posterior diameter and transverse diameter of the frontal lobe were positively correlated with gestational week with correlation coefficients 0.871 and 0.971 respectively. There was a linear relationship between gestational weeks and frontal lobe parameters, and the equations were simplified to obtain the simple correlation formula: fetal frontal lobe anterior-posterior diameter(mm)=14.5+0.7×(gestational week-21), frontal lobe transverse diameter (mm)=41+2.5×(gestational week-21).ConclusionThe reference ranges of the frontal lobe anterior-posterior diameter and the frontal lobe transverse diameter of normal fetuses between 21 to 36 weeks in transcerebellar plane were established, which can provide valuable information for the evaluation of normal development of the frontal lobe and the diagnosis of suspicious fetal microcephaly.What’s already known about this topic?We currently lack a golden standard to diagnosis microcephaly and fetal frontal lobe dysplasia is a clue for prenatal diagnosis of microcephaly.What does this study add?This study presents a novel evaluation of the fetal frontal lobe to better assess brain development in the transcerebellar plane.The fetal frontal lobe developmental diameters will be useful to aid diagnosis of suspicious microcephaly and other cortical developmental disorders.

Objective On the basis of retrospectively analysis the trans-cerebellar section showing the Sylvian fissure of normal fetus is better than trans-thalamic section in middle and late trimester, we prospectively studied the morphological changes of the Sylvian fissure of normal fetus on the trans-cerebellar section in order to provide valuable information for the diagnosis of fetal cerebral cortical dysplasia. Methods A prospective cross-sectional study was conducted on 845 normal fetuses at 21 to 32 weeks of gestation from January 2019 to September 2020. The angle of the posterosuperior horn of the Sylvian fissure was measured. Based on the angle, the morphology of the Sylvian fissure was divided into four shapes included trapezoid shape (Angle >90), square shape (Angle=90); T shape (Angle <90) and I shape (Angl=0). Results The angle of the posterosuperior horn of the Sylvian fissure was negatively correlated with gestational age which correlation coefficient was 0.966 (P < 0.001). Taking gestational age as the independent variable and the angle of posterosuperior horn of the Sylvian fissure as the dependent variable, it showed that there was a linear relationship between the gestational age and the angle of posterosuperior horn of the Sylvian fissure. We got a simple correlation formula that the angle of posterosuperior horn of the Sylvian fissure =140-13X(gestational weeks-21). It was found that the morphological changes of the Sylvian fissure were related to the gestational age. The morphology of the Sylvian fissure was trapezoid shaped at 21 to 24 weeks of gestation, square shaped at 25 to 26 weeks of gestation, T shaped at 26 to 30 weeks of gestation, and the Sylvian fissure was almost closed and appeared I shaped after 31 to 32 weeks of gestation. Conclusion This study preliminarily elucidates that the morphological changes of the posterosuperior horn of the Sylvian fissure of normal fetuses at 21 to 32 weeks of gestation through the trans-cerebellar section, which could provide valuable information for the evaluation of the normal development of the Sylvian fissure and the prenatal diagnosis of cerebral cortical hypoplasia of fetuses. Key words Fetus; Sylvian fissure; posterosuperior horn; morphology; trans-cerebellar section

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 =0.004X (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. Key words Fetus; prenatal ultrasound; transverse diameter of cerebellum; transverse diameter of frontal lobe; microcephaly