| Part I Diffusion tensor imaging for normal neonatal brain myelin developmentObjective:To measure fractional anisotropy(FA)values with application of magnetic resonance diffusion tensor imaging(DTI)quantitative determination.The FA values can reflect the brain white matter microstructure.To discuss the FA values in controlled study of full term and preterm infants and the diversity of FA values in various brain regions and explore the value of DTI application in the cerebral white matter myelin development.Materials and methods:39 term neonates,gestational age in 37～42 weeks and 61 premature infants,corrected to 40 weeks gestational age,were investigated by DTI.Their perinatal medieal records and nervous system examinations were nothing-remarkable.All enrolled newborns were performed routine MRI and DTI scan.FA values in bilateral white matter of cerebellar hemisphere(WMCH),anterior limb of internal capsule,(ALIC),posterior limb of internal capsule(PLIC),frontal periventricular zone(FPVZ),occipital periventricular zone(OPVZ),corpus callosum genu and splenium(CCG and CCS),centrum semiovale(CS),subventricular zone(SVZ),external capsule(EC)and middle cerebellar peduncles(MCP)were analyzed.To analyz FPVZ e differences of FA values in various white matter regions in full term and preterm neonates.Results:① FA values in the same regions of interest(ROI)had no statistic difference between left and right hemisphere(P>0.05).The comparisons of FA values between corpus callosum genu and splenium,in preterm and full term group were all statistical significant(P<0.05).② The FA values between preterm infants and full term infants in various white matter regions were compared,FA values of premature are lower than full term.The comparison of FA values between preterm and term infants in ALIC,PLIC,CCS,CSb,EC and MCP was statistically significant(P<0.05).The comparison of FA values between the two groups in CCG,FPVZ,OPVZ,CSa,SVZ had no significant difference(P>0.05).③ The FA values of premature and full term infants in various WMCH were different and all values were compared in pairs.We found the values in PLIC were higher than in ALIC,the values in OPVZ were higher than in FPVZ,and CCS were higher than CCG.All the differences were statistically significant(P<0.05).The comparison of FA values between CSa and CSb plane had no statistical significance(P>0.05).The FA values of OPVZ were the lowest in all ROIs;and the FA values of CCS and PLIC were highest.The comparison of FA values between OPVZ and CCS,OPVZ and PLIC had significant difference respectively(P<0.05).Conclusion:FA values can evaluate the myelination of premature and full term infants quantitatively,reflecting the late maturity of selected white matter in premature infants.FA values also vary in different regions of the brain,reflecting the myelination time,white matter fiber arrangement and myelin self-structure difference.FA values quantitatively analyze the process of myelination and can evaluate the situation of brain white matter development.Part II The application of MR susceptibility weighted imaging in neonatal hyperbilirubinemiaObjective:The aim of the protocol is to evaluate neonatal intraeranial hemorrhage in neonatal hyperbilirubinemia with susceptibility weighted imaging(SWI),and to explore the value and limitation of SWI compared with conventional magnetic resonance imaging(MRI).Methods and Subjects:We conducted a prospective study including 120 neonates(full term born within 28 days and premature correct gestational age within 42 weeks).Subjects were divided into 4 groups,30 cases in each group.Group 1 is premature infants for physical examination;Group 2 is full term infants for physical examination;Group 3 is premature infants detected high blood bilirubin level in clinical;Group 4 is full term infants diagnosed of hyperbilirubinemia.All 120 neonatal cases received MRI and SWI scanning,two radiologists who don’t know the history of subjects analyzed MRI and SWI images by double blind method.We recorded the detection of hemorrhagic cases and numbers in routine MRI and SWI and analyzed the performances of different parts of the intracranial hemorrhage.Results:① Comparison with MRI and SWI,the detection positive rates of neonatal intracranial hemorrhage were statistically significant(P<0.001),SWI is superior to conventional MRI.In the high blood bilirubin group,the detection positive rates of bleeding in routine MRI and SWI were statistically significant(P<0.05),and in the normal control group,the detection positive rate of bleeding in routine MRI and SWI were not statistical significante(P>0.05).② Among 120 neonates there were 43 cases with intraeranial hemorrhage detected on routine MRI sequences and/or SWI.Among neonates with intraeranial hemorrhage there were 27 preterm and 16 term neonates;29 neonates with high bilirubin and 14 cases of normal control.The differences of incidences between preterm infants and full term were statistically significant(P<0.05).Incidences of neonatal intracranial hemorrhage between high blood bilirubin group and normal control group were compared,differences were significant(P<0.05),including full term and preterm infants.③ Among 43 neonates with intraeranial hemorrhage,there were only 14 cases showed extracerebral hemorrhage(5 cases subdural hemorrhage,1 case subdural hemorrhage combined with cerebral hemorrhage,8 cases subarachnoid hemorrhage).All 14 cases were showed in MRI images and SWI.The detection positive rates of extracerebral hemorrhage between MRI and SWI were not statistical significant(P>0.05).④ 29 cases were detected with intracranial hemorrhage,and among them 10 cases did not be detected on conventional MRI sequences.Neonatal intracranial hemorrhage included germinal matrix-intraventricular hemorrhage,cerebral and cerebellum hemorrhage.The detection positive rates of germinal matrix-intraventricular hemorrhage compared with conventional MRI and SWI has no obvious statistical significance(P>0.05).The parenchymal hermorrhage(including cerebral and cerebellum hemorrhage)always showed the form of microbleeds(foci<10mm),the detection positive rates of SWI is superior to conventional MRI,the differences were considered as statistically significant(P<0.05).⑤ Among 43 cases with intracranial hemorrhage 122 focus were detected,including 19(15.2%)subependymal-intraventricular hemorrhage,43(35.2%)cerebral hemorrhage,46(37.7%)cerebellum hemorrhage,6(4.9%)subdural hemorrhage and 8(6.8%)subarachnoid hemorrhage with SWI.On conventional MRI 78 focus were detected.The comparison was statistically significant(P<0.05).⑥ In our study,the germinal matrix-ventricular hemorrhage was detected more among premature than full term infants.The brain parenchyma hemorrhage and cerebellum hemorrhage were detected among preterm and full term infants.The subdural hemorrhage was detected more among full term infants and subarachnoid hemorrhage was detected more among premature infants.Conclusion:The incidence of neonatal intracranial hemorrhage in premature infants with high blood bilirubin level is higher than normal control infants.SWI is superior to conventional MRI in the detection positive rates and focus numbers of cerebral and cerebellum hemorrhage among infants with high blood bilirubin level and can be used as a powerful supplement to conventional MRI.Part Ⅲ Early identification hypoxic-ischemic encephalopathy by combination of MR imaging and proton MR spectroscopyObjective:Brain damage following a perinatal hypoxic-ischemic encephalopathy(HIE)has been diagnosed by different techniques.The aim of this study is to combine MR imaging with proton MR spectroscopy in HIE diagnosis and to evaluate their correlation with outcome.Materials and Methods:Prospective observational cohort study between February 2012 and February 2013 was carried out.Consecutive newborns,84 full-term neonates with HIE(mild to moderate and severe group)and 10 normal neonates,were included.Two sequential MR studies were performed:a conventional MR imaging for observation in T1WI and T2WI,and proton MR spectroscopy for observation in the left or right basal ganglia and thalamus.MRI were assessed and scored by two neuroradiologists who were blinded to the clinical condition of the infants.Results:①The mild to moderate group(StageⅠ-Ⅱ,n=53)and severe group(StageⅢ,n=31)were similar in visualization of punctate hyperintensity lesions on T1WI and brain edema on T2WI;Differences were that the severe group associated with abnormal SI of thalamus,corpus callosum or brain stem on conventional and diffusion-weighted MR image(P=0.001).②The mean number of PWML in mild to moderate group(stage Ⅰ-Ⅱ)was 5.3 8±4.68(range,1-13).The mean number of PWML in severe group(stage Ⅲ)was 16.82±17.66(range,4-59).We found there was significant difference between two groups in regard to PWML number(P=0.035).Most PWMLs were found close to the medullary veins and showed restricted diffusion on their early MRI.③Mean MR imaging score was 6.20±1.75 for cases of stage Ⅰ-Ⅱ group and 9.78±3.64 for cases of stage Ⅲ group.There was significant difference in the two groups(P=0.009).④The differences of N-acetylaspartate(NAA)/creatine(Cr),choline(Cho)/Cr and lactate(Lac)/Cr in the basal ganglia and thalamus between control group and HIE group,stage Ⅰ-Ⅱ group,stage Ⅲ group were statistically significant respectively(P<0.05).While there were no differences of NAA/Cr,Cho/Cr found between stage Ⅰ-Ⅱ group and stage Ⅲ group(P>0.05).The ratios of Lac/Cr in StageⅢ group increased significantly than StageⅠ-Ⅱ group,Lac/Cr ratios in the two groups have significant difference(P<0.05).Conclusion:The combination of conventional MRI and 1H-MRS can impersonally reflect brain morphology and metabolite changes of HIE neonates,to more accurately dignose the severity of HIE brain injury. |
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