The Application Value Of Magnetic Resonance Diffusion Tensor Imaging In Neonatal Hypoxic-ischemic Encephalopathy

BackgroundHypoxic-ischemic encephalopathy（HIE）refers to cerebral blood flow reduction and abnormal energy metabolism which leads to neonatal brain damage resulted from perinatal asphyxia.Mild cases can be healed,the severe cases can lead to children with cerebral palsy,epilepsy,retardation,low intelligence,and even death.The sequelae resulted from HIE can brings heavy burden to children’s psychology and development,family and society.Therefore,early diagnosis of HIE and accurate assessment in children is very important.At present,clinical diagnosis of HIE is primarily based on whether children with asphyxia and clinical symptoms after birth.It is subjective.does not provide a quantitative standard.Whether the disease affected the development of white matter and myelination is an important basis to determine whether there is movement and mental retardation and other adverse sequelae for HIE.In recent years,with the accelerated development of medical imaging technology,especially the new magnetic resonance imaging（MRI）technology,it plays a very important role in the diagnosis of central nervous system diseases.For the diagnosis of HIE,conventional MRI has some limit and does not provide effective quantitative indicators.Currently,the new magnetic resonance imaging technique,diffusion tensor imaging（DTI）,is more sensitive than conventional magnetic resonance imaging in the early diagnosis of HIE and provides some quantitative indicators for assessing HIE in children.ObjectiveThis study aimed to investigate the value of MR diffusion tensor imaging in the early diagnosis and late follow-up of neonatal hypoxic-ischemic encephalopathy.Methods1.Selected 45 full-term HIE infants from August 2016 to December 2017 who were born and conducted magnetic resonance scanning in our hospital magnetic resonance department.They are divided into mild,moderate and severe groups,HIE diagnostic criteria refers to”neonatal hypoxic—ischemic encephalopathy diagnostic criteria”^[1].In addition,20normal newborns were selected as normal control group.All of the subjects were conducted conventional magnetic resonance scanning sequence and DTI sequence,selected the frontal white matter,semi-oval center,anterior capsule limb,internal capsule limb,genu of corpus callosum,splenium of corpus callosum,and lenticular nucleus as ROIs（region of interest ROI）.Then we calculated FA values in every regions of interest and analyzed these changes about FA between groups.ROC curve were applied to analysis the diagnostic performance of the FA in each region of interest.2.In the late stages of review,collected 20 full-term neonates with HIE who were reconducted cranial MRI of aforementioned 45 HIE neonates.The 20 cases were divided into two groups,review mild HIE group and moderate-severe HIE group.In addition,15normal newborns in same age were selected as normal control group.All of the subjects were conducted conventional magnetic resonance scanning sequence and DTI sequence,selected the frontal white matter,semi-oval center,anterior capsule limb,internal capsule limb,genu of corpus callosum,splenium of corpus callosum,and lenticular nucleus as ROIs.Calculated FA values in every regions of interest and analyzed these changes about FA between groups.Results1.FA values in anterior capsule limb,semi-oval center,internal capsule limb,genu of corpus callosum,splenium of corpus callosum,frontal white matter were different and the difference was statistically significant（P<0.05）.FA values in lenticular nucleus between each groups showed no significant difference（P>0.05）;FA value at posterior limb of internal capsule proved to be superior in diagnosis of HIE.2.In the late stages of review,beside lenticular nucleus,FA values in all ROIs of the moderate-severe group were reduced compared with the control group and the mild group were different and the difference was statistically significant（P<0.05）;FA values in internal capsule limb and splenium of copuscallosum between mild group and control group was different,and the difference was statistically significant（P<0.05）;FA values in lenticular nucleus between each groups showed no significant difference（P>0.05）.Conclusion1.DTI may early,objectively,quantiteti evaluate the extent of brain damage inneonatals with HIE,which may provide important information for early diagnosis and disease assessment.2.FA value can objectively response the injury of white matter fiber tracts and development of white matter fiber tracts in HIE children.