A study of the clearness rate of fetal Sylvian fissure shown on different sections by prenatal ultrasound

Abstract Objective To 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. Methods This 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. Results The 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. Conclusion In 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.