The Development Of Fetal Thoracic Spine In The Second And Third Trimester Of Pregnancy With Intrauterine And Postmortem MRI

Part 1 The development of fetal thoracic spine in the second and third trimester of pregnancy with intrauterine MRIObjectiveTo investigate the change rules of the length of thoracic segment,the height,the anteroposterior diameter,the left and right diameter and the sagittal-section area of T12 vertebrae centrum ossification center(COC)in utero at different gestational age(GA),and the growth curve of the vertebrae was plotted.Materials and MethodsThe 1.5 T MRI was performed on 82 fetuses in utero ranging from 23～38 GA with sequence of the whole spine SWI.The 82 pregnant women were derived from the outpatient department of obstetrics and gynecology of Shandong Provincial Hospital,and prenatal MRI and postpartum MRI re-examination of the fetuses showed no obvious spinal abnormalities.The morphological parameters were measured with the Siemens syngo.via workstation,and the length of thoracic segment,the height,the anteroposterior diameter and the sagittal area of T12 COC were measured in the median sagittal position,the left and right diameter of the T12 COC was measured in the middle crown position.Liner regression equations were established.The regression relationship between the measured data and GA was analyzed,the growth curve was established,and the change rules of intrauterine fetal thoracic spine and T12 COC center were summarized.Results(1)The length of thoracic segment,the height,the anterior and posterior diameters,the left and right diameters,and the sagittal-section area increased linearly with the GA.The linear regression equations:Thoracic length(cm)=-1.034+0.282 × GA(R2=0.914,P<0.05);The height of T12 COC(cm)=-0.143+0.020×GA(R2=0.923,P<0.05);The anterior and posterior diameters of T12 COC(cm)=-0.421+0.031 ×GA(R2=0.926,P<0.05);The left and right diameters of T12 COC(cm)=-0.464+0.039 ×GA(R2=0.925,P<0.05);The sagittal-section area of T12 COC(cm2)=-0.509+0.023×GA(R2=0.944,P<0.05).(2)From 23 w to 3 8w,the development of the fetal thoracic spine is unbalanced.There were three peeks during growth period.The growth peaks of thoracic length,the height and sagittal-section area of T12 COC basically coincided,all around 25～26w,31～32w,and 35～36w.Meanwhile,the maximum growth peak is around 25～26w.(3)There is no gender difference in the development of the thoracic spine and T12 COC of the intrauterine fetuses.ConclusionThe relationship between the length of thoracic spine,the height,the anteroposterior diameter,the left and right diameter and the sagittal-section area of the T12 COC show a strongly linear correlation with GA in the second and third trimester intrauterine,which was a reliable index for evaluating the growth of the fetal spine,providing an objective imaging basis for clinical evaluation of the normal development of the fetal thoracic spine.Part 2 The development of fetal thoracic spine in the second and third trimester of pregnancy with postmortem MRI and contrast with the intrauterine fetusObjectiveTo assess the growth rules of the thoracic segment,the height,the anteroposterior diameter,the left and right diameter and the sagittal-section area of T12 COC in specimens with different stages of GA.The growth curve and line graph of growth rate were plotted,and compared with the intrauterine fetus to explore the differences between the two methods of studying fetal spinal development.Materials and MethodsThe 3.0 T MRI was performed on 52 postmortem fetuses ranging from 20～38 GA with sequence of the whole spine 3D-T2WI.The 52 fetal specimens were derived from sectional anatomy research center of the Cheeloo College of Medicine of Shandong university,and the fetal specimens showed no obvious spinal abnormalities with CT and X-ray scanning.The morphological parameters were measured with the Siemens syngo.via workstation,and the length of the thoracic segment,the height,the anteroposterior diameter and the sagittal area of T12 COC were measured in the median sagittal position,the left and right diameter of the T12 COC was measured in the middle crown position.Liner regression equations were established.The regression relationship between the measured data and GA was analyzed,the change rules of intrauterine fetal thoracic spine and T12 COC center were summarized and compared with the study results of intrauterine fetal thoracic spinal development.Results(1)The length of the thoracic segment,the height,the anterior and posterior diameters,the left and right diameters,and the sagittal-section area increased linearly with the GA.The linear regression equations:Thoracic length(cm)=-0.946+0.280×GA(R2=0.973,P<0.05);The height of T12 COC(cm)=-0.153+0.021×GA(R2=0.946,P<0.05);The anterior and posterior diameters of T12 COC(cm)=-0.256+0.029×GA(R2=0.970,P<0.05);The left and right diameters of T12 COC(cm)=-0.371+0.041×GA(R2=0.938,P<0.05);The sagittal-section area of T12 COC(cm2)=-0.436+0.025×GA(R2=0.974,P<0.05).(2)From 20w to 38w,there were also three growth peeks of thoracic length,the height and sagittal-section area of T12 COC in fetal specimens as follow:25～26w,31～32w,and 35～36w,the maximum growth peak is around 25～26w.It is same as intrauterine fetuses.(3)There is no gender difference in the development of the thoracic spine and T12 COC of the postmortem fetuses.(4)According to the comparison of parameters related to the linear regression equation between intrauterine and postmortem fetuses,the slope of the equation(i.e.regression coefficient)was similar,and the constant of the equation(i.e.longitudinal axial intercept)was different;Compared with intrauterine fetal and fetal specimens,there were no significant differences in the thoracic length and morphological parameters of T12 COC.ConclusionBy comparing the thoracic spinal development of intrauterine fetuses and postmortem fetuses,a more objective and standard reference standard for fetal spinal development can be obtained,which further improves the accuracy of clinical judgment of fetal spinal development by taking the thoracic spine as an example.