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62Chapter3Today different imaging modalities are able to acquire the 3D shape of the newborn’scranium The3dMDCranialSystemisabletocapturea360-degree fullheadimageandisspecificallydesignedforsurfaceimagingofthecranialshapeTheclinicalreproducibilityof the3DMDacquisitionsystem wasinvestigatedbyMaaletalandwasfoundtobe04mm20Thesystemerrorofthe3DMDsystemwasdescribedbyBoehnenandFlynn21andwasfoundtobe±01mmThemostimportantadvantagesof3Dstereophotogrammetryarethefastandshortacquisitiontime(lessthan2ms)andthefactthatthereisnoexposuretoionizingradiation922Therefore3DstereophotogrammetryisagoodimagingmodalitytostudythecranialshapeofthepatientandtomonitoritsdevelopmentovertimeAlthoughdifferentstudiesclaim that theyuse theadvantagesof3Dstereophotogrammetrymoststudiesdonotusethefullpotentialof3Dstereophotogrammetryandtendtoreproducesimple2Danthropometrics23–27Severalstudiespresentedexcellent3Devaluationmethodsfortheskullyetthesestudiesused3DCT.28–31Tothebestofourknowledgenootherstudieshaveused3Dstereophotogrammetryincombinationwithacomplete3Devaluationof thecranialshape fordiagnosisanddetectionofcranialabnormalitiescomparedtonormalcranialshapevariationsByusingPCAonadatabaseof3Dphotographsofcontrolstheaverage3DcranialshapeandthevariationsofthecontrolpopulationweredeterminedUsingthismethodwecancomparea3Dphotographnotonlytotheaveragecranialshapebutalso to therangeofnormal variationsin thecontrolpopulation Thisisasubtleandelegantwaytodeterminehowmuchapatient’scranialshapedeviates fromashapethatisassumedtobe ‘normal’.ScaphocephalypatientsarecharacterizedbyanelongatedcranialshapeintheanteroposteriordirectionandareducedlateraldiameterofthecranialshapemediotemporallyToalesserextentthismorphologicalvariationisalsopresentinanormalpopulationsincetherearenewbornswithmorerounderornarrowerheadshapes32ThereforeitwasexpectedthatwecoulduseamultiplicationofthesenormalvariationstodetectthescaphocephalyshapeIndeedmanipulatingthe fourselectedPC’s forscaphocephalypatients to themeancranialshapeclearlyconfirmedthishypothesisbyrevealinganelongatedcranialshapewithareducedlateraldiameter(Figure5)Thisproveswecreatedanaccuratemethodfortheidentificationofscaphocephaly
