Fetal Cervical Enlargement Development In Normal Second And Third Trimester Of Pregnancy:A Postmortem MRI Study And Ultrasonic Comparative Study Of Cervical Spine

PART Ⅰ Cervical cord length in normal second and third trimester of pregnancy and Ultrasonic comparative study of cervical spineObjectiveTo study the normal development of the fetal cervical cord length at different gestational ages using postmortem MRI. Using the magnetic resonance imaging(MRI) and Ultasound to measure the normal fetal cervical spine length at 29～36 weeks gestational ages.Materials and methodsWe performed a study on 44 fetal specimens ranging from 16～42 gestational weeks. Three-dimensional (3D) T2-weighted (WI) imaging and Sampling Perfection with Applcation-optimized Contrast using differented flip Angle Evolution (T2W-SPC) of the cervical spine were performed and then images were reconstructed in the coronal, axial, and sagittal planes. The length of cervical cord was measured up from the top of the first cervical nerve root bottom to top of the first thoracic nerve root at different gestational ages. Using the magnetic resonance imaging (MRI) and Ultasound to measure the normal fetal cervical spine length in the sagittal planed at 29～36 weeks gestational ages, to compare the accuracy.ResultsThere were significant linear relationships between the length of cervical cord and gestational age (cervical spine length= 0.12 X gestational age+0.11, R2=0.92, P<0.05). There were no significant differences of the cervical cord length between sexes.ConclusionsFetal MRI shows the the fetal cervical cord length clearly. Fetal cervical cord length can be used to evaluate gestational age in the second and third trimester of pregnancy, We aimed to establish an MRI image map and database of normal fetal cervical cord. The accuracy of MRI and Ultrasound in measuring the normal fetal cervical spine length at 29～36 weeks gestational ages is no difference.PART Ⅱ Fetal cervical enlargement development between 16 and 42 weeks gestational age:A postmortem MRI studyObjectiveTo investigate the normal development of fetal cervical enlargement, its length, its maximum cross-sectional area and its relative position at different gestational ages using postmortem MRI.Materials and methodA total of 44 fetal specimens ranging from 16-42 gestational weeks were enrolled. Three-dimensional (3D) T2-weighted (WI) imaging and Sampling Perfection with Application-optimized Contrast using differenced flip Angle Evolution (T2W-SPC) of the cervical spine were performed and then images were reconstructed in the coronal, axial, and sagittal planes. The following lobular parameters were measured:① the relationship between length of cervical enlargement and gestational age;② the relationship between maximum cross-sectional area of cervical enlargement and gestational age; ③ the relative position of cervical enlargement at different gestational ages; ④ the significant differences in ervical enlargement length and cervical enlargement maximum cross-sectional section area between sexes.Results①There were significant linear relationships between the cervical enlargement length and gestational ages (cervical enlargement length=0.08 X gestational age-0.06, R2 =0.91, P<0.05). ②There were significant linear relationships between the maximum cross-sectional area and gestational ages (cervical enlargement maximum cross-sectional area=0.01 X gestational age-0.12, R2=0.91, P<0.05). ③ The maximum section of fetal cervical enlargement was located in the center of C5/6 at 16-28 gestational weeks and in the center of C5-C5/6 at 29-42 gestational weeks. The relative position of the maximum cross-sectional area of fetal enlargement gradually increased over gestation. ④ There was no significant difference in cervical enlargement length and cervical enlargement maximum cross-sectional section area between sexes.ConclusionsHigh field MRI clearly shows the cervical enlargement, its length, its maximum cross-sectional area, and its relative position over gestation. We have established an MRI image map and database of normal fetal cervical enlargement.