The Application Of Magnetic Resonance Imaging In Fetal Central Nervous System And Vertebras

In the circumstances of the two-child policy in China,the birth rate of the second child has been rising.The second child has more requirements of prenatal diagnosis than the first child because of higher risk of malformation.Prenatal ultrasound screening can partly meet the needs of prenatal imaging diagnosis,but there are still significant limitations in fetal central nervous system.Magnetic resonance imaging is an advanced imaging device without invasive and radiation damage.It has a significant advantage in the imaging diagnosis in central nervous system of children and adults.But the applications in fetuses are still brand new fields in magnetic resonance imaging diagnosis.So,at first,in order to understand the fetal magnetic resonance imaging and lay the groundwork for our study,we introduced research status of fetal brain development and the relevant magnetic resonance imaging combined with histology and embryology.Then,we evaluated the asymmetry development of fetal brain with fast magnetic resonance sequence,represented by bilateral superior temporal sulcus.The results showed the superior temporal sulcus was visible after 23 gestational week.The left superior temporal sulcus lagged behind the contralateral 2 GW.We can conclude that the bilateral superior temporal sulcus of human fetal were asymmetric,which may be related to the function divisions of fetal bilateral cerebral hemisphere.Abnormal asymmetry pattern may be associated with neuropsychiatric diseases.And then,we evaluated the value of fetal magnetic resonance imaging in evaluating fetal intracranial space occupying lesions comparing to prenatal ultrasound,in order to make further statement on the advantages of MRI in fetal central nervous system.It has been proved that MRI could provide more information about the minor lesions,such as intracranial hemorrhage and periventricular nodules.And it could provide the whole view of the intracranial lesion in order to delineate the surrounding structure.But there are some limitations of its soft tissue contrast in a case with teratoma,we should make more effort to improve the sequences.Based on the cases with fetal intracranial space occupying lesions,we found 4 cases with a rare malformation called dural sinus malformation.We explain the reason for dural sinus malformation of different locations with the help of histology and embryology,and analyzed the possible mechanism of associated neuronal migration disorder.Compared with ultrasound screening,prenatal MRI could not only make the diagnosis of dural sinus malformation,but also evaluate the whole brain of the fetus.It could find the possible associate malformation and provide more information for prognosis consultation.At last,as the vertebral malformation is common in fetuses with central nervous system malformation and the ultrasound is unsatisfying in bone imaging,we compared the ability of SWI sequence and T2-truefisp sequence in evaluating fetal vertebral malformation in order to take place of the prenatal CT and reduce the unnecessary radiation exposure of fetuses and pregnant women.We gained that the SWI sequence can provide better contrast between calcified bone tissue and surrounding soft tissue than T2-truefisp sequence,so it could delineate the spine malformation more clearly.SWI could also be considered to be used in fetal skeletal dysplasia,skull base and craniofacial bone malformation and even postmortem MRI examination.