The Value Of Abdominal Three-dimensional Ultrasound Volume Contrast Imaging Plus C-plane Technique In Differentiating Cystic Malformation Of Posterior Cranial Fossa

Objective(VCI-C)was used to evaluate the development of fetal cerebellar vermis and the diagnostic value of cystic deformity in the posterior cranial fossa was studied by using three-dimensional ultrasound volume contrast imaging combined with C-plane technique(VCI-C).MethodsA total of 267 normally developed fetuses at 18-32 gestational weeks were examined prospectively in Wuxi Maternity and Child Healthcare Hospital.Two-dimensional ultrasound was used to measure the bipolar diameter,head circumference,abdominal circumference and femur length of the fetus.Three-dimensional ultrasound volume contrast imaging plus C-plane Technique was used to obtain the mid-sagittal view of he cerebellar vermis.The cerebellar vermis morphology,internal structure and the relationship with the surrounding adjacent tissue were observed carefully.The diameter and perimeter of the cerebellar vermis were measured,and VP / FL and VC/FL were calculated.The relationships between the above indexes and gestational age were analyzed.46 cases were selected for the diagnosis of posterior cranial cystic deformity after MRI or autopsy after the abortion.Then divide them into two groups.Case 1 group includes: mega cisterna megna,Blake’s pouch cyst and arachnoid cyst of posterior cranial fossa.Case 2 group includes: vermian agenesis and vermian hypoplasia.The same method was used to measure the observed parameters,compared with the normal group.Results1.Normal group fetal head sagittal plane sagittal ultrasound performance: cerebellumfull shape,shaped like half "orange petals",and the angle between the brain stem is almost0 degrees,the top of the fourth ventricle was triangular during pregnancy 18-32 weeks.Half of the "orange petal" shaped cerebellar vermis and the fastigial of the fourth ventricle can be clearly shown after 18 gestational weeks.But the primary fissure,secondary fissure and 9 lobes show unclear.Part of the fetal primary fissure can be seen,secondary fissure and 9 lobes were vaguely visible after 27 gestational weeks.The primary fissure,secondary fissure and 9 lobes could reveal clearer after 30 gestational weeks.2.In normal fetuses,perimeter and cranio-caudal diameter of CV were positively correlated with gestational weeks and increased with gestational weeks during pregnancy18-32 weeks.Correlation coefficient(r)was 0.989 和 0.955(P<0.001)respectively.VP/FL was 1.2±0.06,VCC/FL was 0.36±0.03,and they does not have a correlation with gestational weeks。3.Case 1 group ultrasound performance : 16 cases of mega cisterna megna fetal ultrasound performance for the posterior fossa pool width of 12-15 mm,cerebellar vermis of the measured values are within the reference range;7 cases of Blake’s pouch cyst ultrasound performance: the diameter of the posterior fossa pool <10mm,the dilated fourth ventricle was communicated with posterior foss,the CV in the sagittal plane observation parameters were at the normal reference value Range and the CV was upward rotated;5cases of arachnoid cyst of posterior cranial fossa ultrasound showed echo free zone in the cranial fossa pouch(diameter 5mm-28mm),not communicated with the posterior fossa pool,cerebellar vermis of the measured value in the normal reference range.4.Case 2 group ultrasound performance: 11 cases of cerebellar vermis agenesis of the performance of cerebellar vermis partial loss,the measured value is less than the normal reference value of the fifth percentile;7 cases of cerebellar vermis hypoplasia ultrasound showed cerebellar vermis integrity,VP and VCC were less than the normal reference value,the primary fissure and secondary fissure could not displayed,The strong echo branches were less than those of the same gestational weeks.5.Case 1 group: VP/FL was 1.2±0.03,VCC/FL was 0.35±0.02 during pregnancy18-32 weeks,There was no significant difference between the case 1 group and normal group(P> 0.05).6.Case 2 group: VP/FL was 0.85±0.06,VCC/FL was 0.27± 0.02,There wassignificant difference between the case 2 group and normal group(P< 0.05).Conclusion1.Transabdominal three-dimensional ultrasound VCI-C technique can clearly show18-32 weeks of fetal cerebellar vermis morphology,subtle structure,can be applied to differential diagnosis of the posterior cranial cystic deformity.2.The VP and VCC increased with gestational weeks at 18 to 32 gestational weeks,VP/FL was 1.2±0.06,VCC/FL was 0.36±0.03.