| Eugenics is the basic national policy of our country.Antenatal diagnosis and development evaluation of fetal diseases are important measures for eugenics.In particular,imaging examination plays an irreplaceable role in the detection,evaluation and intervention of fetal malformations,stunting and other developmental abnormalities and diseases,and has become the most important and directest means of antenatal examination.The main methods of fetal imaging examination are ultrasound(ultrasound)and magnetic resonance imaging(magnetic resonance imaging,MRI).Ultrasound is the first choice of imaging method for fetus.But due to the limitation of soft tissue resolution,it can not display the fine structures of the fetal brain perfectly.In recent decades,MRI technology,which has been rapidly developed and popularized,provides superior soft tissue resolution and has become a necessary means for further diagnosis after ultrasound examination,especially in central nervous system imaging.However,due to the influence of field intensity,scanning time and fetal movements,the display ability of fine structures of fetal brain anatomy can not meet the research requirements,which leads to the lack of a scientific and systematic high-resolution MRI map of sulcus development as the basis for judging brain development.Sulci are the most intuitive structure on the surface of the cortex and the most obvious morphological change in the process of corical development.The development of sulcus can be used as a criterion to judge whether a fetal brain is mature or not.The sylvian fissure is the earliest one among all sulci,and it is a relatively stable structure as well as an important anatomical marker for the boundary between frontoparietal lobe and temporal-occipital lobe.Thus,investigating the morphology and variation of the fetal sylvian fissure is of great clinical significance to making antenatal evaluations in terms of fetal brain development degree and cortical developmental malformations.Based on this,this study aimed to obtain MRI images of sylvian fissures of normal fetal brain specimens under the 7.0T ultra-high field MRI in order to establish a standard map of fetal brain development and study the imaging data as well as the related data of the development of the fetal sylvian fissure with gestational weeks.This study is divided into two parts:(1)A study of sylvian fissure's basic morphology and the relationship between the depth of sylvian fissure and gestational age in 14-22 gestational weeks fetal specimens.(2)A study of three-dimensional reconstruction of sylvian fissure and quantitative analysis of the relationship between the surface area,volume and gestational age in 14-22 gestational weeks fetal specimens.Part 1 A study of sylvian fissure s basic morphology and the relationship between the depth of sylvian fissure and gestational age in 14-22 gestational weeks fetal specimens.Objective:To study the basic morphology and regularity of sylvian fissure of fetal brains by 7.0T magnetic resonance imaging scanning at 14-22 gestational weeks.Materials and methods:In this study,65 fetal specimens from 14 to 22 gestational weeks with normal brain development after ultrasound and 3.0T magnetic resonance screening were collected.46 samples with higher image quality were finally involved after knocking out those with artifacts and other adverse reasons.The fetal brain MR images were obtained under 7.0T high field magnetic resonance instrument scanning,and the T2WI images were introduced into Amira 5.2.The image of T2WI was introduced into Amira 5.2,the sylvian fissure was identified and its morphological outline was sketched,and the basic shape,depth and development law with gestational age were observed.The depth of the sylvian fissure was defined as a line at the end of the sylvian fissure on a specific sylvian fissure plane which was perpendicular to the straight line between the frontoparietal lobe and the temporal lobe.Through statistical analysis,the correlation between the depth of sylvian fissure of fetal brain and gestational age was judged.Results:The 7.0T high field intensity MRI images of the brain in 14-22 gestational weeks were obtained.The two-dimensional morphology and depth of the left and right fetal sylvian fissures at different gestational weeks were described at a specific level.The basic changes of the two-dimensional morphology were as follows:the sylvian fissure was like a shallow wavy in 14-15 gestational weeks,a shallow ladder in 16-17 gestational weeks,a ladder in 18-19 gestational weeks,a wide mouth ? in 20-21 gestational weeks,and a ? type in 22 gestational weeks.The depth of sylvian fissure increased linearly.With gestational weeks as transverse coordinates and left and right depths as longitudinal coordinates,scatter plot and regression analysis were carried out.The respective regression equations were Y=0.3555X-2.4183,r=0.719;Y=0.3916X-3.0442,r=0.8128.It shows that the depth of sylvian fissure is positively correlated with gestational age.Conclusion:Through the study of the basic morphology of the fissure of the fetal brain during the middle pregnancy,the template of the development law has been established.The depth of the sylvian fissure is gradually deepened with the increase of the gestational age and is positively correlated with the gestational age at 14-22 gestational week.The basic morphology of sylvian fissure follows the variation of depth from shallow to deep and that of opening from large to small.This template can be used as a standard and reference for judging fetal brain development and providing a reference for the evaluation of fetal development during clinical antenatal period.Part 2 A study of three-dimensional reconstruction of sylvian fissure and quantitative analysis of the relationship between the surface area,volume and gestational age in 14-22 gestational weeks fetal specimens.Objective:The volume and surface area of fetal sylvian fissure were studied by 7.0T magnetic resonance scanning in 14-22 gestational weeks,and the relationship between the volume and surface area of fetal sylvian fissure and gestational age was analyzed.Materials and methods:In this study,65 fetal specimens from 14-22 gestational weeks with normal brain development under ultrasound and 3.0T magnetic resonance screening were collected.46 samples with higher image quality were finally involved after knocking out those with artifacts and other adverse reasons.The fetal brain MR images were obtained under 7.0T high field magnetic resonance instrument scanning,and the T2WI images were introduced into Amira 5.2 software.The sylvian fissure was identified and its shape and outline are sketched.Two different colors are respectively given to the left and right side of the sylvian fissure.The mapped image of fetal sylvian fissure was reconstructed by using the 3D reconstruction technology of the software,and the volume and surface area of the sylvian fissure after reconstruction were automatically measured by the software.Through statistical analysis,the correlation between the surface area,volume of sylvian fissure of fetal brain and gestational age was judged.Results:The 3D reconstruction model and the related data of 7.0T high field strength MRI in the 14-22 gestational weeks were obtained.The scattered point diagram and regression analysis were made with the transverse coordinates of gestational age and the surface area and volume of left and right side as longitudinal coordinates.The regression equations of the left and right surface areas were as follows:Y=47.157X-593.41,r2=0.8113;Y=38.565X-457.86,r2=0.8145.The regression equations of left and right volume are Y=34.094X-472.61,r2=0.7697;Y=24.535X-316.54,r2=0.7749.It was proved that the surface area and volume of sylvian fissure of 14-22 gestational week were positively correlated with gestational age.Conclusion:The reconstruction of the fetal sylvian fissure by relevant software shows the morphology of sylvian fissure more intuitively,which provides new material for clinical application and teaching.The conclusion that the surface area and volume of fetal sylvian fissure at 14-22 gestational week positively correlated with gestational age further deepens the reliability of using sylvian fissure as a reference for clinical judgment of fetal development during middle pregnancy. |
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