| Part One Study on cerebral blood flow dynamics of normal full-term neonates with three-dimensional arterial spin labeling perfusion imagingObjective : This study aims to investigate the application value of three-dimensional arterial spin labeling in cerebral blood flow dynamics of full-term neonates and to investigate the effect of age-related factors on the cerebral blood flow of normal neonates.Methods:A total of 60 full-term neonates without known intracranial pathology were scanned with 3T MR brain 3DASL sequence and routine sequence.These neonates were divided into three groups: 1-3 day group,4-7 day group,and 8-15 day group.GE AW4.6 post-processing workstation was imported with the 3DASL image and the CBF diagram was obtained with the Functional software.On the cerebral blood flow images,regions of interest were selected from the frontal white matter,parietal white matter,basal ganglia,corona radiata,thalamus and brainstem,and the CBF values of each ROI were recorded.The CBF values of ROIs at bilateral symmetric positions,the values of each ROI between males and females,and the values of each ROI among these three different age groups were compared.Results:1.The difference in CBF values of the frontal white matter,parietal white matter,basal ganglia,corona radiata and thalamus at the bilateral symmetric positions was not statistically significant(P > 0.05).There was no statistical difference in the CBF values of each brain region between the male and female groups(P > 0.05).2.The CBF values at the basal ganglia region,corona radiata and parietal white matter were higher in the 8-15 day group,when compared with that of the 1-3 day and 4-7 day groups(P < 0.05).The CBF value at the basal ganglia region was higher in the 4-7 day group,when compared with that of the 1-3 day group(P < 0.05).The CBF value at the frontal white matter was lower in the 4-7 day group,when compared with that of the 1-3 day and 8-15 day group(P < 0.05).The CBF value at the brainstem was higher in the 4-7 day group,when compared to the 1-3 day and 8-15 day groups(P < 0.05).Conclusion:1.In this study,the conventional multimodal parameter MR brain functional imaging combined with the new technology of 3DASL was used to conduct an early dynamic study on the brain functional injury of HIE,and the MRI parameters of brain functional evaluation in this study were optimized,which was innovative.2.The research results confirmed that 3DASL technology can clearly show the abnormal changes of blood flow signals in different brain regions of neonates,and it is a non-invasive,rapid and accurate MRI technology of the evaluation of neonatal brain functional injury.3.The results showed that the CBF values of basal ganglia region,corona radiata and parietal white matter in the 8-15 day group were higher than those of the 1-3 day group and the 4-7 day group(P < 0.05),and the CBF values of basal ganglia region in the 4-7 day group were higher than those of the 1-3 day group(P < 0.05),suggesting that the CBF values of these brain regions increased with the increase of daily age.It indicated that with the increase of daily age,the metabolism and oxygen consumption of the brain were increased due to the increase of myelin activation and synaptic density in the neonatal brain,which could increase the cerebral blood flow.4.In clinical application,the gender factor of neonates had no significant effect on CBF value;The effect of daily age on CBF value was studied by using the method of bilateral control.Part Two Study on cerebral hemodynamics of ASL in hypoxic-ischemic encephalopathy of neonates at different ageObjective:To investigate the application value of 3DASL in cerebral hemodynamics of neonates with hypoxic-ischemic encephalopathy.Methods:60 normal full-term neonates and 60 HIE neonates were scanned with 3T MRI 3DASL sequence and routine sequence.Normal neonates and HIE neonates were divided into 1-3 day group,4-7 day group and 8-15 day group according to their daily age.GE AW 4.6 post-processing workstation was imported with the 3DASL image,and the CBF diagram was obtained with the Functool software.On the CBF diagram,the frontal,parietal white matter,basal ganglia,corona radiata,thalamus and brainstem were selected at symmetrical positions on both sides to record the CBF values of each ROI,and the CBF values of bilateral symmetric parts were averaged.The cerebral blood flow of HIE neonates in 1-3 day group,4-7 day group and 8-15 day group was compared with that of normal neonates at corresponding daily age,to summarize the cerebral hemodynamic characteristics of neonates with HIE at different daily age.Results:1.The CBF value of basal ganglia,thalamus and brainstem of HIE neonates in 1-3 day group was higher than that of normal neonates in 1-3 day group,with statistically significant difference(P < 0.05);the CBF value of frontal lobe was lower than that of normal neonates,with statistically significant difference(P < 0.05);the CBF value of corona radiata was slightly higher than that of normal group,and the CBF value of parietal lobe was lower than that of normal group,with no statistically significant difference(P > 0.05).2.The CBF value of basal ganglia,thalamus,corona radiata and frontal lobe of HIE neonates in the 4-7 day group was lower than that of normal neonates in the 4-7 day group,with statistically significant difference(P < 0.05);the CBF value of brain stem was higher than that in the normal group,with no statistically significant difference(P > 0.05);the CBF value of parietal lobe was lower than that in the normal group,with no statistically significant difference(P > 0.05).3.The CBF value of each brain region of HIE neonates in the 8-15 day group was not significantly different from that of normal neonates in the 8-15 day group(P > 0.05).Conclusion:1.Statistical analysis indicated that the basal ganglia,thalamus and brainstem CBF values in the 1-3 day HIE group were higher than those in the 1-3 day normal group,and the difference was statistically significant(P<0.05).It indicates that early HIE neonates have blood flow redistribution and reperfusion injury in the central gray matter area,because these areas have higher metabolism and higher oxygen demand in the immature brain.2.The CBF values of the frontal lobe and parietal lobe in the 1-3 day HIE group were lower than those in the normal group,and the difference was statistically significant(P < 0.05),indicating that cerebral blood flow in the peripheral white matter area was decreased in order to ensure the most vigorous metabolism in the central gray matter area.3.The basal ganglia,thalamus,corona radiata and frontal lobe CBF values of HIE neonates in the 4-7 day group were lower than those in the 4-7 day group,and the difference was statistically significant(P < 0.05).It suggested that cerebral blood flow was decompensated in most brain regions during this period,and cerebral blood flow was mostly regulated by blood pressure.However,long-term hypoxia resulted in decreased cardiac output and blood pressure,so cerebral perfusion decreased accordingly.4.There was no significant difference between the cerebral blood flow in most brain areas of the 8-15 day HIE group and the normal group,so the optimal time window for evaluating cerebral hemodynamics of HIE was optimized within 7 days.5.Early hyperperfusion in basal ganglia and thalamus is helpful for early diagnosis of HIE and assessment of prognosis.Part Three Application value of ASL in neonatal hypoxic-ischemic encephalopathy classification and prognosis evaluationObjective: To investigate the correlation between CBF value of hypoxic-ischemic encephalopathy in neonates and neurobehavioral measurement of neonates(NBNA),the relationship between early changes of CBF value and prognosis of neonates with hypoxic-ischemic encephalopathy,and the consistency between HIE clinical grade and MR grade.Methods: Forty newborns with hypoxic-ischemic encephalopathy underwent MR plain scan of the head and 3DASL sequence scan.According to the clinical classification,there were three groups: mild,moderate and severe,and the MR classification was divided into normal,mild,moderate and severe.The consistency of the two classifications was compared.The differences of CBF values among three groups were compared.According to the NBNA score,neonates were divided into three groups: the group with more than 35 points had a good prognosis,and the group with less than 35 points had a bad prognosis.The differences in CBF values between the two groups were compared.The correlation between CBF value and NBNA score was compared.Results:1.There was a strong consistency between clinical score and MR score(Kappa =0.672,P < 0.001).2.CBF values of basal ganglia region in the mild,moderate and severe groups were 24.02±3.03,29.10±1.93 and 38.28±7.53.The CBF value of the thalamus was 25.90±2.17,30.46±5.04 and 36.16±8.24.The NBNA score was 38.82 ± 0.41,37.00 ± 0.87 and 32.42 ± 2.78.The differences were statistically significant(P < 0.05).3.CBF value of basal ganglia was 40.80 ± 8.15 and 27.87 ± 3.85 respectively in the group with poor prognosis and the group with good prognosis.The CBF value of the thalamus was 39.53±7.55 and 28.76±4.65,respectively,in the group with poor prognosis and the group with good prognosis.The NBNA score was 30.88±1.96 and 37.44±1.32 respectively in the group with poor prognosis and the group with good prognosis.The differences were statistically significant.4.CBF value in the basal ganglia region was closely correlated with NBNA score,showing a negative correlation(r=-0.908,P < 0.05).The CBF value of thalamus was closely correlated with NBNA score,showing a negative correlation(r=-0.754,P < 0.05).Conclusion:1.The results of the study confirmed that clinical indexing of HIE was consistent with the indexing results of 3DASL imaging evaluation.It is suggested that this research method is innovative,effective and practical,and it is a non-invasive MRI technique to evaluate the functional injury of neonatal brain.2.Statistical data analysis confirmed that the basal ganglia,thalamus CBF value and NBNA scores between the clinical classification of mild,moderate and severe are statistically significant(P < 0.01),suggesting the basal ganglia,thalamus CBF value in mild,moderate and severe of neonats showed a trend of rising,shows that the two parts of the CBF value is higher,the condition is heavier,basal ganglia,thalamus early CBF value can be objectively and visually reaction severity HIE.3.The CBF value of basal ganglia region,thalamus and NBNA scores between the prognosis group and good prognosis group were statistically significant(P < 0.01)and prognosis of cerebral perfusion is higher than the good prognosis group of cerebral perfusion,indicates CBF value can assess reperfusion associated with delayed cell death phenomenon,thus can be used to predict the result of brain injury and neuroprotective therapy as early as possible.4.The correlation between CBF value in basal ganglia area and NBNA score was close and negative.The correlation between thalamic CBF value and NBNA score was close and negative.Therefore,the higher the perfusion of basal ganglia and thalamus was,the lower the NBNA score was and the worse the prognosis was.5.ASL combined with conventional MR multimodal scanning technology and NBNA score can more comprehensively grade HIE and accurately evaluate clinical prognosis,providing more medical imaging information for early clinical treatment. |
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