Nuchal Translucency And Nasal Bone Measurement At 11 To 14 Weeks Of Gestation Using Three-dimensional Ultrasound

ObjectiveUltrasound examination has already been recommended as a important prenatal screening test for fetal morphological anomaly.Nuchal translucency(NT) measurement at 11 to 14 weeks of gestation is also necessary.The thickeness of NT and nasal bone(NB) abnormality has close relationship to chromosomal abnormality,especially in trisomy 21.Our study investigate the feasibility of NT measurement and NB observation through standard midsagittal section acquired by three-dimensional(3D) ultrasound.The evaluation of superiority and clinical value of 3D ultrasound technology is also been discussed.MethodsBetween January,2008 and January,2009,in our study,203 pregnant women were examined in Shenjing hospital affiliated to China medical university.The crown-rump length(CRL) were ranging from 45mm to 84mm,while gestational age were at 11 weeks 2 days to 14 weeks 2 days of gestation,the age of pregnant women were between 21 to 45 year-old.The criteria for NT thickeness was widen than 3mm.The value of NT,its relation to gestational age and the time for midsagittal section acquirement were respectively obtained by 2D and 3D ultrasound,and the difference were analysed.Besides,the existence of fetal NB were also respectively observed,and the detection rate were compared.The time limit for 3D image storage and 2D value acquirement were 20 minitues.ResultsIn all 203 fetuses,5 cases were detected NT thickness,in which 1 was diagnosed as thrisomy 21 and 4 were diagnosed as cystic hygroma with NT thickeness.Standard midsagittal section can be acquired in 198 fetuses with 3D rotation and extended imaging.The statistical assessment for all 198 fetuses showed that the difference of NT values measured by 2D and 3D ultrasound was not significant(t=0.488 p=0.626>0.05), positive correlations were found between NT value and gestational age for both(r=0.536,p<0.05;r=0.543,p<0.05).For the time of standard midsagittal section acquirement,3D ultrasound is shorter than 2D(p<0.05).Nasal bone were clearly showed in 87.4%of 198 fetuses,the detection rate were similar.Conclusion1,Reconstruction and 3D extended imaging could obtain standard midsagittal section essential for NT measurement,so it was feasible to measure NT by 3D ultrasound,and its clinical value should be confirmed.2,Time for standard midsagittal section acquirement by 3D ultrasound was shorter than those by 2D.So if fetus was in bad position,standard midsagittal section was not easy to get,we could first obtain the 3D data volume,regarded parasagittal section as its starting plane,and then reconstruct the standard midsagittal section by rotation.The time for examination can be shortened.3,Nasal bone length showed positive correlations to the gestational age in the fetuses between 11⁺²-14⁺² gestational age.The detection rate of nasal bone by 2D and 3D ultrasound were similar.