Prenatal Ultrasonic Research Of Fetal Hippocampus And Fornix In The Second And Third Trimester

BackgroundThe hippocampus is the cortex belongs to the limbic system and located in the temporal lobe.It plays an important role in learning,perceptibility and emotion.It also functions in emotional and neuroendocrine control.Diseases such as epilepsy,depression,Alzheimer's disease and schizophrenia are closely related to the structure.Studies have confirmed that hippocampus have changes in some cerebral cortex congenital abnormalities.The fornix is a part of the limbic system either.It is the main efferent fiber of the hippocampus.Its fiber connect the frontal lobe,temporal lobe and bilateral cerebral hemisphere.Studies have shown that patients who suffer fornix injury in the surgery may suffer affective disorders or transient memory disorders.Degeneration of the fornix can be found in some degenerative diseases such as Alzheimer's disease.Consider the important role of the hippocampus and the fornix in the central nervous system,lots of research were on the topic in recent years,including the drug effect on hippocampus,hippocampus and related genes expression,influence of pathological state on hippocampus,the morphological and structural development of the hippocampus,segmentation of the hippocampus,diseases related to the hippocampus such as Alzheimer's disease,depression,cognitive dysfunction,etc.Recent studies of the fornix include the changes of the fornix in diseases,the microanatomy of the fornix,the fiber connection of the fornix,fornix damage and its influence,and segmentation of the fornix.MRI is the most regular method in the scanning of hippocampus and fornix for its high resolution and definite localization in the central nervous system examination.Relative studies include 3D reconstruction,anatomy of adult hippocampus,development of fetal hippocampal formation with 7.0T MRI,morphological construction of the fetal hippocampus,the diagnosis of hippocampal diseases,and the diffusion tensor imaging of the fornix.Due to the block of skull,ultrasound can hardly cross the brain and limited its use in the scanning of adult central nervous system.However,in the fetal and neonatal periods,the skull has not yet matured and the fontanelle is wide so that the brain can be clearly observed by ultrasonography.As a routine prenatal screening method,ultrasonography is fast,convenient,safe and real time imaging,which can be used to screen fetus for several times and used in the observation of hippocampus and fornix.Fetal MRI scanning is not regular and limited by the influence of fetal movement and mother's breathing.Compared with ultrasonography,MRI is disadvantage.So far,the research objects on hippocampus and fornix by ultrasonography is neonates and premature but not the fetuses.To improve the understanding of fetal fornix and hippocampus,we designed the research on prenatal ultrasonic research of fetal fornix and hippocampus in the second and third trimester.The study consist of three parts:(1)Prenatal ultrasonic study of the development fetal hippocampus and the establishment of its normal reference value;(2)Prenatal ultrasonic study of the development fetal fornix and the establishment of its normal reference value;(3)The development of hippocampus and fornix in the fetuses with central nervous system abnormalities.Chapter1 Prenatal ultrasonic study of the development fetal hippocampus and the establishment of its normal reference valueObjectiveTo explore the observation and evaluation method of fetal hippocampus using two-dimensional and three-dimensional volume ultrasound in prenatal transabdominal examination of fetuses in the second and third trimester.Compare the differences between the two methods and hemispheres.Measure the parameters of the hippocampus including superior to inferior diameter,left to right diameter,antero-posterior diameter and establish the normal reference value.MethodsFrom October 2016 to December 2017,381 singleton pregnant women between 21-40 gestational weeks were selected,whom took prenatal ultrasound screening in Shenzhen maternal and child health care hospital affiliated to Southern Medical University.Maternal age,height,weight,inspection time,gestational weeks,last menstrual period,menstrual history,routine examination results of the fetus in early pregnancy ultrasound examination were recorded.Samsung WS80A and Samsung A30 Doppler instruments(the frequency of probe:1-8MHz)were used in the observation of the hippocampus.The section included the axial section and the coronal section of the hippocampus.Parameters of the hippocampus including superior to inferior diameter,left to right diameter,antero-posterior diameter and the common growth parameters of the fetus were recorded.Statistical software SPSS20.0 was used for statistical analysis.The data were expressed by mean ± standard deviation or median(range interquartile).P<0.05 was set as the statistically significant.Forty normal fetuses were selected randomly for interobserver variability.Two-dimension and three-dimension difference,hemispheric difference was compared.Correlation analysis between these parameters and gestational age were conducted and the normal reference value of these parameters were established.ResultsThe best observed gestational weeks in the hippocampus were 24-34 weeks due to the development stage and the skull ossification.There was no significant difference in the hippocampal parameters between two observers,between hemispheres,and between two-dimensional and three dimensional methods(all P>0.05).A significant positive linear correlation between the parameters and gestational age(GA)was found in normal group(r = 0.863,0.866,0.901,R2 = 0.745,0.749,0.812),linear regression equations were:superior to inferior diameter=0.044GA-0.253cm,left to right diameter = 0.040GA-0.264cm,antero-posterior diameter = 0.069GA-0.498cm,respectively.ConclusionPrenatal ultrasound can be used to observe the fetal hippocampal structure and make a preliminary assessment of its development.There is no significant difference between the two and three-dimensional measurements.The size of the left and right hippocampal parameters in the second and third trimester is almost the same.The normal reference value of the hippocampal parameters can be used as a reference for the development of prenatal ultrasound assessment.Chapter 2 Prenatal ultrasonic study of the development fetal fornix and the establishment of its normal reference valueObjectiveTo explore the observation and evaluation method of fetal fornix using two-dimensional and three-dimensional volume ultrasound in prenatal transabdominal examination of fetuses in the second and third trimester.Compare the differences between the two methods and two hemispheres.Measure the parameters of the fornix including fornical column length diameter,fornical column short diameter,fornical body length diameter,fornical body short diameter and the distance between two side of the fornical body.Establish the normal reference value of these parameter.MethodsFrom October 2016 to December 2017,381 singleton pregnant women between 21-40 gestational weeks were selected,whom took prenatal ultrasound screening in Shenzhen maternal and child health care hospital affiliated to Southern Medical University.Maternal age,height,weight,inspection time,gestational weeks,last menstrual period,menstrual history,routine examination results of the fetus in early pregnancy ultrasound examination were recorded.Samsung WS80A and Samsung A30 Doppler instruments(the probe frequency:1-8MHz)were used in the observation of the fornix.The observation section included the axial section of the fornical body and the coronal section of the fornical column.Parameters of the fornix including fornical column length diameter,fornical column short diameter,fornical body length diameter,fornical body short diameter and the distance between two side of the fornical body,all the common growth parameters of the fetus were recorded.SPSS20.0 statistical software was used for statistical analysis.The data were expressed by mean±standard deviation or median(range interquartile).P<0.05 was set as the statistically significant.forty normal fetuses randomly selected for interobserver variability.Two-dimensional and three-dimensional difference,hemispheric difference were compared.Correlation analysis between these parameters and gestational age were conducted and the normal reference value of these parameters were established.ResultsThe best observational gestational weeks of the fornix were 22-34 weeks due to the effects of developmental stage and the ossification of the fetal skull.There was no significant difference in the fornical parameters between two observers and between hemispheres(all P>0.05).Except the left side of fornical column short diameter,right side of fornical column length diameter and the distance between two side of the fornical body,there was no significant difference in the other fornical parameters between two-dimensional and three dimensional methods(all P>0.05).A significant positive linear correlation between the parameters including fornical column length diameter,fornical column short diameter,fornical body length diameter,fornical body short diameter and gestational age(GA)was found in normal group(r=0.854,0.821,0.734,0.590;R2 = 0.729,0.674,0.539,0.348).Linear regression equations were:fomical column length diameter = 0.036GA-0.103,fornical column short diameter = 0.007GA-0.005,fornical body length diameter =-0.033GA+ 0.088,forrnical body short diameter=0.040GA+ 0.013,respectively.The earliest gestational age of the fornical body fusion was 22 gestational age.ConclusionPrenatal ultrasound can be used to observe the fetal brain fornix and make a preliminary assessment of its development.There is no obvious difference between the two dimensional and three-dimensional measurements in some parameters of fornix.The size of the left and right fornix columns and the fornix body in the second and third trimester is almost the same.The normal reference value of the diameter of the fornix can be used as a reference for the evaluation of the development of the prenatal ultrasound.Chapter 3 The development of fornix and hippocampus in the fetuses with central nervous system abnormalitiesObjectiveTo explore the hippocampal and fornical parameters of fetuses with central nervous system abnormities and to evaluate the value of normal reference value established in chapter 1 and chapter 2.MethodsFrom October 2016 to December 2017,407 singleton pregnant women between 21-40 gestational weeks were selected in the study,whom took prenatal examination in the Shenzhen maternity and child health care hospital affiliated to Southern Medical University,including 381 normal fetuses(normal group)and 26 fetuses with central nervous system abnormities(mainly including lissencephaly/pachygyria,corpus callosal dysplasia,hypoplasia of the cerebellar vermis).Maternal age,height,weight,inspection time,gestational weeks,last menstrual period,menstrual history,routine examination results of the fetus in early pregnancy ultrasound examination were recorded.Samsung WS80A and Samsung A3 0 Doppler instruments(the frequency of probe:1-8MHz)were used in the observation of the hippocampus.Hippocampal parameters including superior to inferior diameter,left to right diameter,antero-posterior diameter and fornical parameters including fornical column length diameter,fornical column short diameter,fornical body length diameter,fornical body short diameter were measured.SPSS20.0 statistical software was used for statistical analysis.The data were expressed by mean ± standard deviation or median(range interquartile).P<0.05 was set as the statistically significant.Gestational age and maternal age were compared in two groups.The parameters of fornix and hippocampus were compared in two groups.ResultsThere were no significant differences in Gestational age and maternal age between two groups.Except the fornical short diameter,other parameters had significant differences between the normal and abnormal groups(all P<0.05).ConclusionThe hippocampal parameters including superior to inferior diameter,left to right diameter,antero-posterior diameter,and fornical column length diameter,fornical body length diameter,fornical body short diameter are smaller in the fetuses with central nervous system anomalies.We should pay more attention to the development of hippocampus and fornix in the fetuses with central nervous system anomalies.