Correspondence
Replytocorrespondence:Prenataldiagnosisof centralnervoussystemabnormalities:
Neurosonographyversusfetalmagnetic resonanceimaging
DearEditors,
WereadwithinteresttheletterofTanacanetal.[1],aboutthe role of ultrasound i.e. Neurosonography (NS) compared to MagneticResonanceImaging(MR)inprenataldiagnosisoffetal brainmalformations.Accordingtotheauthorsfindings,itseemsto benosignificantdifferencebetweenthediagnosticperformanceof thesetwotools,atanygestationalage.
Severalpointshowevershouldbediscussed.On thebasisof currentliterature,inthelastdecades,fetalMRimaginghasbeena valuableadjuncttooltoadetailedultrasoundexaminationdueto itsspreadclinicaluseandrapidtechnologicalimprovementssuch asultra-fastimagingsequencesanddiffusionweightedimaging.
AlthoughNSremainsthemainstaychoiceinprenatal evalua-tionoffetalbraincongenitalanomaliesowingtoitslowcost,easy availabilityandwell-establishedliterature,fetalMRimagingcan provide useful complementary information showing several advantages:comparedtoNS,fetalMRovercomemanytechnical challengesshowingahighersensitivityandspecificityofin the diagnosisofcorpuscallosumabnormalities.Intheassessmentof the posterior fossa structures, fetal MR with its multiplanar capabilities can evaluate better the morphology of the vermis helpinginthedifferentialdiagnosisofDandy-Walker malforma-tion;inaddition,itisabletoevaluatethesupratentorialstructures which are difficult to explore by NS, especially in the third trimester where ossification of the skull can limit ultrasound assessmentoftheposteriorfossastructures[2].Moreover,fetalMR imagingisparticularlyusefulinmonochorionictwinpregnancies complicatedbytwin-twintransfusionsyndromeorco-twinfetal demisewhereNSmaybeunrevealing.Evenintheassessmentof fetal ventriculomegaly, forwhich it is wellknownan excellent agreement between NS and MR, the latter showed a better detectionrate for sometypesof possibleassociated anomalies, particularlyinthethirdtrimester,highlightinganemergingroleof fetalMR imaginginthedefinitionoftheprognosisof ventricu-lomegaly, withsignificant implications on parental counselling andperinatalmanagement[3,4].Recently,fetalMRIhasbecomea valuable tool in the evaluation of openspinal dysraphisms for predictingthelevelofthespinaldefectwhichhasanimpacton prenatalcounselling,neurologicprognosis,andeligibilityforfetal surgery[5]
LimitationsofMRareparticularlyevidentatlowergestational age(suchas<20weeks),whenMRimagingmayhaveareduced specificity:thismayberelatedtosmallsizeofsomestructuresof
the brain, fetal motionand difficulty in obtaining a true mid-sagittalimage.Follow-upMRimaging,eitheratalatergestational ageorpostnatally,isrecommendedinsuchcases[2].
In summary, magnetic resonance imaging is a safe and promisingtechniquecomplementtoneurosonographyinprenatal evaluation of cerebral abnormalities and screening of high-risk fetuses.Itcanprovideadditionalusefulinformationthatcanalter clinical management in terms of prognostic value of the counselling. Radiologistsand fetal medicineexpertsinvolved in themanagementshouldbeawareofthepotentialandlimitations oftheavailablefetalimagingtools,tooptimisethe multidisciplin-arycareforpregnantwomen.
DeclarationofCompetingInterest
Theauthorshavenoconflictofintereststodeclare. References
[1]TanacanAtakan,OzgenBurce,FadilogluErdem,UnalCanan,OguzKaderKarli. MehmetSinanBeksacprenataldiagnosisofcentralnervoussystem abnormali-ties:neurosonographyversusfetalmagneticresonanceimaging.EurJObstet GynecolReprodBiol2020;250(May)195–202,doi:http://dx.doi.org/10.1016/j. ejogrb.2020.05.013Onlineaheadofprint.
[2]MalingerG,Ben-SiraL,LevD,Ben-AroyaZ,KidronD,Lerman-SagieT.Fetalbrain imaging:acomparisonbetweenmagneticresonanceimaginganddedicated neurosonography.UltrasoundObstetGynecol2004;23:333–40.
[3]Fantasia I, Bussani R, Gregori M,et al. Intrauterine versus post-mortem magneticresonanceinsecondtrimesterterminationofpregnancyforcentral nervoussystemabnormalities[publishedonlineaheadofprint,2020Apr23]. EurJObstetGynecolReprodBiol2020;250:31–5,doi:http://dx.doi.org/10.1016/ j.ejogrb.2020.04.032.
[4]GhesquièreL,Houfflin-DebargeV,VerpillatP,etal.Contributionoffetalbrain MRIinmanagementofseverefetalanemia.EurJObstetGynecolReprodBiol 2018;228:6–12,doi:http://dx.doi.org/10.1016/j.ejogrb.2018.05.044.
[5]NagarajUD,BierbrauerKS,StevensonCB,etal.PrenatalandpostnatalMRI findingsinopen spinaldysraphism followingintrauterine repairviaopen versusfetoscopicsurgicaltechniques.PrenatDiagn2020;40(1):49–57, doi: http://dx.doi.org/10.1002/pd.5540.
IlmaFlorianaCarbone*
DepartmentofObstetricsandGynecology'L.Mangiagalli', Fonda-zioneIRCCSCa'Granda,OspedaleMaggiorePoliclinico,Milan,Italy GabrieleSaccone DepartmentofNeuroscience,ReproductiveScienceandDentistry, UniversityofNaplesFedericoII,Naples,Italy *Correspondingauthor. E-mailaddress:ilmafloriana@gmail.com(I.Carbone). Received2June2020 Availableonlinexxx
https://doi.org/10.1016/j.ejogrb.2020.07.038
0301-2115/©2020ElsevierB.V.Allrightsreserved.
EuropeanJournalofObstetrics&GynecologyandReproductiveBiologyxxx(2019)xxx
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EURO11510No.ofPages1
Pleasecite this article in press as: I.F. Carbone, G. Saccone, Reply to correspondence: Prenatal diagnosis of central nervous system abnormalities: Neurosonography versus fetal magnetic resonance imaging, Eur J Obstet Gynecol (2020), https://doi.org/10.1016/j. ejogrb.2020.07.038
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