Reproducibility of 3-dimensional sonographic measurements of fetal and placental volume at gestational ages of 11-18 weeks

PURPOSE: Determine the reproducibility of 3D ultrasound (3DUS) measurements of fetal and placental volumes. METHODS: We included 34 pregnant women between gestational weeks (GW) 11-18. Two operators independently acquired fetal and placental volumes using 3DUS. Each volume was acquired twice and stored on disk for off-line analysis. Intra- and interobserver reproducibility was expressed in the intra- and interclass correlation coefficient (intra-CC and inter-CC). In addition, the 3DUS volumes acquired by the first operator were calculated by the second and vice-versa to evaluate the effect of volume acquisition and caliper placement. A value >0.75 was considered a good agreement. RESULTS: Fetal and placental volume measurements were successful in 97% of all cases. Between GW 11-14 and 14-18 the median fetal volume was 20.8 (5.0-35.1) and 51.7 (37.9-132.8) ml, the median placental volume was 71.3 (40.9-111.9) and 120.7 (94.2- 273.7) ml. Bland-Altman plots were used for statistical analysis. The intraobserver reproducibility was good for fetus (intra-CC: 0.99; 0.99) and placenta (intra-CC: 0.99; 0.98). Also, interobserver reproducibility was good for fetus (inter-CC 0.98) and placenta (inter-CC 0.98). In addition, regardless of the operator who acquired the volumes, the inter-CC remained good for both fetus (inter-CC: 0.99; 0.99) and placenta (inter-CC: 0.97; 0.99). CONCLUSION: The reproducibility of fetal and placental volume measurements by 3DUS between GW 11-18 is good. In addition, individually chosen caliper placement and volume acquisition has no effect on the calculation of either volumes.     

不同旋转步长三维超声体积自动测量技术测量体积准确性的仿体实验研究

目的测试三维超声体积自动测量技术在不同旋转步长下的误差。方法将大小形状不同的离体新鲜猪肉组织块置于水囊中,对目标物进行三维容积采样后,启动三维超声体积自动测量程序,分别使用旋转步长30°、15°、9°、6°测量组织块的体积,记录数据并进行统计。结果使用旋转步长30°、15°、9°、6°的误差分别为(14.49±7.45)%,(10.93±5.97)%,(6.05±5.06)%和(12.92±6.77)%。测量体积与实际体积的相关回归方程分别为y=1.0642x 0.8374(r=0.9903),y=1.0674x 0.5093(r=0.9936),y=1.0235x 0.6614(r=0.9968),y=1.0514x 0.7767(r=0.9927),以上方程P<0.05。其中旋转步长为9°时,r值最大。不同旋转步长测量条件下,实际体积与相对误差的相关系数r值在0.2083～0.3762之间。结论三维超声体积自动测量技术对体积的测量结果与实际体积相关性较高,可用旋转步长为9°进行精测,30°进行估测。