MRI Diagnosis And Postnatal Neurodevelopmental Follow-up Of Fetal Corpus Callosum Abnormalities

Part ?MRI Quantification Study on Normal Fetal Corpus Callosum in Middle and Late PregnancyObjectiveThe length and thickness of fetal corpus callosum were quantified by MRI,and the reference range of normal fetal corpus callosum was established to provide basis for diagnosis of fetal corpus callosum abnormality.Materials and methodsThe MRI data of normal brain anatomical structure of 99 fetuses from 24 to 38 gestational weeks were retrospectively collected.Magnetic resonance imaging(MRI)was performed by Philips Achieva Nova Dual 1.5T device with 16-channel abdominal surface coil,and all fetuses were scanned and diagnosed by MRI diagnosticians.Dispense with injecting sedative or contrast agent or holding breath,the pregnant women were scanned in supine position or lateral position by routine three-plane scanning with single-shot fast spin-echo(SSFSE)sequence(black blood sequence)in the first place to obtain cross-sectional,coronal and sagittal images of the fetal brain.The data collected in this group were the MRI images of the midsagittal section of the fetal brain and clearly showing various parts of the corpus callosum,which were taken as the enrolled cases;the total length of corpus callosum and the thicknesses of genu,body and splenium of corpus callosum of the fetuses at different gestational weeks were measured by 2 radiologists with more than 10 years of MRI diagnosis experience at the midsagittal section and SSFSE sequence.Correlation analysis was performed to the total length,thicknesses of various parts and gestational weeks of the fetuses.The fetuses were divided into three groups according to gestational age:Group 1,24?28 gestational weeks(n=33);Group 2,29?33 gestational weeks(n=36);and Group 3,34?38 gestational weeks(n=30).The measured data were evaluated by intraclass correlation coefficients(ICC)for the repeatability of the measured values between 2 radiologists.The repeatability was poor if ICC<0.4,ordinary if ICC was 0.4?0.7,and good if ICC>0.7.Spearman rank correlation coefficient was used to analyze the correlation between the total length of fetal corpus callosum,the thicknesses of various parts of the corpus callosum and the gestational weeks,and the reference range of normal group was established.The fitting curve and the regression equation were obtained.Test level:a=0.05.P<0.05 was considered as statistically significant difference.ResultsThe normal fetuses of the same gestational age measured by two radiologists had good repeatability of the corpus callosum diameter lines(ICC>0.7)(Table 1),so the MR measured values of the corpus callosum radial line of the fetuses could be the average value of the two values.The reference ranges of various diameter lines of fetal corpus callosum in three groups were as follows:genu:1.92±0.15mm,2.16±0.23mm,2.69±0.54mm;body:1.52±0.11mm,1.67±0.10mm,1.87±0.28mm;splenium:2.30 ± 0.36mm,2.92±0.34mm,3.89±0.56mm;length:30.69±2.99mm,38.21±2.04mm,42.16 ± 2.93mm.Correlation analysis results showed that the thicknesses of genu,body,splenium and total length of fetal corpus callosum were positively correlated with gestational weeks(r=0.706,0.773,0.808,0.908,all P<0.001).The regression equations were as follows:genu=0.011 gestational weeks2-0.576 gestational weeks+9.557(R2=0.573,P<0.001),body=0.001 gestational weeks2-0.007 gestational weeks+1.214(R2=0.423,P<0.001),splenium=0.005 gestational weeks20.173 gestational weeks+3.407(R2=0.604,P<0.001),the length of corpus callosum=-0.036 gestational weeks2+0.304 gestational weeks-32.690(R2=0.842,P<0.001).Conclusion1.MRI can quantify the thickness and total length of the normal fetal corpus callosum,and can provide a reference for the diagnosis of fetal corpus callosum abnormality.2.The total length and thicknesses of various parts of the normal fetal corpus callosum are linearly correlated with gestational weeks.Part ?Prenatal MRI Diagnosis of Fetal Corpus Callosum AbnormalitiesObjectiveTo explore the value of MRI in the diagnosis of different types of fetal corpus callosum abnormalities and related complicating malformations,and to analyze the changes in induced labor rate of fetus before and after pregnancy guidance.Materials and methodsA total of 6155 fetuses(person-time,including 6073 single fetuses and 82 twin fetuses)who received MRI in our center from May 2014 to July 2021 were analyzed retrospectively,among which,167 fetuses were diagnosed with corpus callosum abnormalities by MRI.The MRI findings of fetal corpus callosum abnormalities and the presence or absence of other complicating cranial and extracranial malformations were analyzed,and the diagnosis results of MRI and the ultrasound results were compared.The MRI examination was performed by Philips Achieva Nova Dual 1.5T device with 16-channel abdominal surface coil,and all fetuses were scanned and diagnosed by MRI diagnosticians.Dispense with injecting sedative or contrast agent or holding breath,the pregnant women were scanned in supine position or lateral position by routine three-plane scanning with single-shot fast spin-echo(SSFSE)sequence in the first place to obtain cross-sectional,coronal and sagittal images of the fetal brain.For fetuses with suspected corpus callosum abnormalities,additional balanced fast field echo(BFFE)sequence would be performed,generally 2-4mm thin layer scanning was required.If fetal movement affected the image quality,repeated scans were required until the image quality met the diagnostic criteria.Radiologists had obtained ultrasound report results before performing MRI scanning to the pregnant women,so they would then analyze MRI images on PACS system to determine the type of fetal corpus callosum abnormalities and whether it is complicated with other related abnormalities.Statistical analysis was performed to determine the characteristics of fetal corpus callosum abnormalities,the proportion and difference of different corpus callosum abnormalities.Kappa analysis was used to analyze the diagnostic consistency between prenatal ultrasound and MR.The consistency was good if Kappa value>0.75 and poor if Kappa value<0.4.The expectant parents should be informed that if the corpus callosum abnormalities were not complicated with other multiple malformations or chromosomal abnormalities,about 80%of children with corpus callosum abnormalities might have a good prognosis after birth,and the changes in fetal induced labor rate before and after informing the expectant parents of the possible prognosis of the corpus callosum abnormalities were analyzed.Results1.There were 167 cases of corpus callosum abnormalities in this study,of which 161 were single fetuses and 6 were twin fetuses(one of them).(1)There were 118 cACC cases,accounting for 76.8%(118/167),the typical MRI findings were as follows:?The cross section images showed that the cavum septi pellucidi disappeared,and the posterior horn of bilateral ventricles showed "teardrop dilation",the average value of dilated lateral ventricles exceeded 13.5mm.? The coronal section images showed that the anterior horn of bilateral ventricles showed "horn like"changes,and the cavum septi pellucidi and corpus callosum structure disappeared.?The sagittal section images showed no normal intact corpus callosum structure.(2)There were 28 pACC cases,accounting for 9.2%(28/167),including 19 cases with only corpus callosum genu and 9 cases with genu and partial body;the MRI findings were as follows:? The cavum septi pellucidi may exist or may not exist.? When the genu existed,the cross section images showed T2WI hypointense shadow running transversely on the anterior horn of the lateral ventricle,and the coronal section showed the presence of the genu above the anterior horn.?The body was mainly displayed in the sagittal section.?The residual corpus callosum was manifested as SSFSE or BFFE hypointense shadow on MRI.(3)There were 21 cases of corpus callosum dysgenesis,of which 18 cases were thin,accounting for 12.1%(18/167),and were manifested as presence but thin morphology of various parts of corpus callosum on MRI,and corpus callosum dysgenesis was often complicated with cranial abnormalities and malformations;3 cases were hyperplastic malformation,accounting for 1.7%(3/167),and were manifested as presence but thickened morphology of various parts of the corpus callosum on MRI.2.According to MRI,corpus callosum abnormality can be isolated(i.e.only manifested as corpus callosum abnormality,and the bilateral ventricular dilation and the cavum septi pellucidi are usually the accompanied signs),and can also be often complicated with other signs,including:? Complicated with other craniocerebral abnormalities,such as posterior cranial fossa widening(42 cases),midline arachnoid cyst(30 cases),cerebral cortex abnormality(23 cases),cerebellar vermis dysgenesis or Dandy walker malformation(14 cases),microcephaly(9 cases),cerebral hemorrhage(4 cases),and midline lipoma(4 cases).? Extracranial abnormalities,including renal abnormalities(10 cases),abnormalities of the great vessels of the heart(7 cases),single umbilical artery(4 cases),microphthalmia(2 cases),nasolacrimal duct cyst(2 cases),gallbladder hypospadias,chest wall vascular malformation,talipes equinovarus,and intestinal volvulus(1 case each).3.The comparison between the diagnosis results of prenatal ultrasound and MRI showed that the prenatal ultrasound clearly diagnosed 17.3%(29/167)of corpus callosum abnormalities,identified 25.1%(42/167)of suspected corpus callosum abnormalities,and prompted 57.4%(96/167)of indirect signs,including 69 cases of unilateral or bilateral ventricular dilation,31 cases of small or unclear cavum septi pellucidi,10 cases of midline cyst,5 cases of small head circumference and 1 case of cerebellar abnormality;the indirect signs overlapped with each other.4.The total induced labor rate of this group was 80.8%(135/167).After the pregnancy guidance regarding the relevant contents was added in October 2018 and the expectant parents were informed of the possible prognosis of the corpus callosum abnormalities,the induced labor rate decreased from 92.3%(96/104)to 61.9%(39/63).Conclusion1.MRI can clearly diagnose and classify fetal corpus callosum abnormalities,and can be used as one of the effective supplementary diagnosis means of prenatal ultrasound.2.Fetal corpus callosum abnormalities is prone to be complicated with other craniocerebral abnormalities or extracranial malformations.Accurate prenatal diagnosis of the related malformations with MRI is helpful to evaluate whether the fetus suffers complex corpus callosum abnormalities and to provide a basis for perinatal consultation.3.The probability of pregnant women selecting pregnancy termination was significantly reduced after adding perinatal consultation and informing the pregnant women of the type and the possible prognosis of corpus callosum abnormalities.Part ?Postnatal Neurodevelopmental Follow-Up of Fetal Corpus Callosum AbnormalitiesObjective58 children diagnosed with corpus callosum abnormalities during fetal period and born successfully were followed up to explore the postnatal neurodevelopmental prognosis of children with fetal corpus callosum abnormalities.Material and methodsThe fetal MRI examination data from 2011 to 2021 were retrospectively followed up,and a total of 58 children who were diagnosed with corpus callosum abnormalities were born successfully(29 cases were examined by prenatal MRI in our hospital;another 29 cases came from the prenatal MRI examinations of other units across the country,and were analyzed through online consultation and data transmission).The prognosis of corpus callosum abnormalities was comprehensively analyzed from four aspects,including:? Analysis of prenatal MRI findings:including clearly determining the type of corpus callosum abnormality and whether it was complicated with other craniocerebral malformations and extracerebral malformations.?Genetic examination:amniocentesis and umbilical cord blood examination were not performed for 22 cases before and after birth;amniocentesis or umbilical cord blood examination was performed for 30 cases before birth;chromosome or gene testing was performed for 8 cases after birth(including 2 cases with negative results of prenatal amniocentesis).? Clinical phenotype:after birth,the child patients were observed to determine whether there were abnormalities in cranium and face,heart,limbs and genitalia.?Evaluation of neurodevelopment quotient:after birth,the child patients were evaluated by Gesell Neurodevelopment Scale,including gross motor,fine motor,personal adaptability,language and social behavior.Four degrees were divided according to the developmental quotient score:normal,85?114;mild neurodevelopment retardation,70?84;moderate neurodevelopment retardation,50?69;severe neurodevelopment retardation,less than 50.ResultsThe results of 58 cases of corpus callosum abnormalities in this group are as follows:? MR findings:There were 53 cases of single pregnancy diagnosed with corpus callosum abnormalities,and 5 cases of twin pregnancy diagnosed with corpus callosum abnormalities(one fetus).There were 38 males and 20 females.There were 36 cases of cACC,16 cases of pACC and 6 cases of corpus callosum dysgenesis.? Genetic testing:in this group,no chromosome or gene testing was performed for 22 cases before and after birth(22/58);chromosome or gene testing was performed for 28 cases before birth,the results were negative and no other abnormality was complicated after birth,so simple corpus callosum abnormality was considered(28/58);2 cases were negative through prenatal amniocentesis but suffered multiple malformations after birth,so complex corpus callosum abnormalities were considered,and postnatal gene testing was abnormal(2/58);the other 7 cases were found to be with face,hand,foot,cleft palate and other related malformations or obvious neurocognitive development retardation after birth,and underwent chromosome or gene testing(7/58),of which,the postnatal chromosome testing of 1 case was negative and there was no simple corpus callosum abnormality.? Postnatal clinical phenotype:9 cases were found to be complicated with multiple malformations,including 4 cases of facial abnormalities,8 cases of hand abnormalities,4 cases of foot malformations,10 other abnormalities,and 1 case complicated with cerebral cortex dysplasia.? Neurodevelopment function evaluation:56 cases underwent neurodevelopment quotient evaluation(56/58)after birth,with an average score of 82.20.The follow-up age ranged from 4 months to 10 years,with an average age of 24.3 months.Statistical analysis showed that there was no statistically significant difference in the DQ score between cACC and pACC,and no statistically significant difference in the average DQ score between the dysgenesis type and cACC and pACC.However,the children with dysgenesis had significant statistical difference in fine motor and adaptability compared with cACC and pACC,and the score was lower.In this group,normal neurodevelopment accounted for 57.1%(32/56),mild neurodevelopment retardation accounted for 25.0%(14/56),and moderate and severe neurodevelopment retardation accounted for 17.9%(10/56).2 cases were complicated with multiple malformations(2/58),and were not evaluated due to their families chose to give up after birth.There were 53 single fetuses,52 of which were evaluated by neurodevelopment quotient,with an average score of 84.34.There were 5 twin fetuses with one fetus having corpus callosum abnormality,and 4 cases were evaluated by neurodevelopment quotient,with an average score of 61.58.Conclusion1.The prognosis of isolated fetal corpus callosum abnormalities was generally good,and the prognosis and clinical manifestations of children with complex corpus callosum abnormalities,corpus callosum dysgenesis or twin pregnancy were relatively poor,and the probability of complicating with chromosomal or genetic abnormalities increased.2.Accurate evaluation of prenatal ultrasound or MRI and improvement of chromosomal examination can reduce the risk of complex corpus callosum abnormalities of the fetus with corpus callosum abnormality after birth.