Methods And Application Of Fetal Cerebellar Vermis Detection And Masurement With Transabdominal Three-dimensional Ultrasonography

Objective To investigate the methods of detecting and measuring fetal cerebellar vermi(sCV) with trans-abdominal three-dimensional ultrasonography (3D US), to observe minute structure of CV and establish the normal data of CV, and to evaluate the CV development basing on the normal data and structure feature.Methods Fetuses between 16 and 41 gestational weeks(GW) were examined by trans-abdominal 3D US and observed their CV minute structures in the mid-sagittal section. The CV sizes (anteroposterior length,cranio-caudal length,perimeter,surface area) in 438 healthy controls were measured and calculated in the mid-sagittal view. The correlation between the CV sizes and pregnant weeks was analyzed. The repeatability and consistency were analyzed with ICC and Bland-Altman analysis respectively when 2D US/3D US measurements were applied to examined 20 fetuses selected randomly.28 fetuses with CV malformations were investigated,including 10 ones with isolated CM,4 ones with Dandy-Walker and 14 ones with Dandy-Walker variant. The CV development of 28 cases were evaluated and compared with pathology.Results (1) Fetal CV minute structures could be observed with 3D US, the fissures between sublobes were hyper-echoic and the intralobar parts were hypo-echoic. The fourth ventricle was discovered in 19 GW, primary fissure ,secondary fissure and sublobes were more and more clear with fetuses grew, nine sublobes of CV were seen until 27 GW.(2)In all healthy controls, the CV sizes(anteroposterior length,cranio-caudal length,perimeter,surface area) increased with GW increasing. The regression equations were: perimeter(mm)= =-0.026GW~2 +4.289GW-39.421, R~2=0.967; surface area (cm2)=0.004GW~2 -0.005GW-0.569, R~2=0.958; anteroposterior length(mm)= =-0.008GW~2 +1.229GW-11.013, R~2=0.925; cranio-caudal length (mm)= =-0.006GW~2 +1.217GW-11.034, R~2=0.923, P<0.05. (3) The repeatability and consistency of the CV data obtained with 3D US and 2D US were all perfect, either by the same doctor or two different doctors; The repeatability of the CV data obtained with 3D US were better than that of 2D US, and the repeatability of the CV area was the best. (4) In the mid-sagittal section:â‘ There was no or hardly any recognizable vermis in DWM, vermis area of DWM was smaller significantly than healthy controls, isolated CM and DWV(P=0.001,0.001,0.003,respectively); primary fissure and secondary fissure could not be detected or displayed unclearly, lobules of the vermis were less arborized , the fastigial recess of the fourth ventricle was shallow and relatively flat .â‘¡Vermis area of DWV was smaller than healthy controls and isolated CM(P=0.000, 0.006); vermis shape was not well-stacked and inferior vermis became smaller and sharp-pointed in DWV, primary fissure and secondary fissure were not displayed clearly, folia of the lobules were less and smoother ,the fastigial recess of the fourth ventricle was shallow.â‘¢There was no difference of CV area between isolated CM and healthy controls(P=0.743); vermis shape was well-stacked , and there was no difference of CV sublobes between isolated CM and healthy controls.Conclusions Fetal CV minute structures can be observed with 3D US and the CV development be evaluated quantitatively . The CV area in the mid-sagittal section by 3D US was the best index. It is helpful to differentiate DWM, DWV and isolated CM to compare the 2D US and 3D US with pathology.