Comparison of Fetal Nuchal Fold Thickness Measurements by Two- and Three-Dimensional Ultrasonography (3DXI Multislice View).

Purpose. To compare the measurements of fetal nuchal fold (NF) thickness by two-dimensional (2D) and three-dimensional (3D) ultrasonography using the three-dimensional extended imaging (3DXI). Methods. A cross-sectional study was performed with 60 healthy pregnant women with a gestational age between 16 and 20 weeks and 6 days. The 2D-NF measurements were made as the distance from the outer skull bone to the outer skin surface in the transverse axial image in the suboccipital-bregmatic plane of the head. For the 3D we employed the 3DXI multislice view software, in which 3 × 2 tomographic planes was displayed on the screen and the distance between the tomographic slices was 0.5 mm. Maximum, minimum, mean, and standard deviation were calculated for 2D and 3D ultrasonography, as well the maximum and minimum, mean, and standard deviation for the difference between both methods. The Wilcoxon signed-rank test was used to compare the two different techniques. Results. 2D-NF showed a mean of thickness of 3.52 ± 0.95 mm (1.69-7.14). The mean of 3D-NF was 3.90 ± 1.02 mm (2.13-7.72). The mean difference between the methods was 0.38 mm, with a maximum difference of 3.12 mm. Conclusion. The NF thickness measurements obtained by 3D ultrasonography were significantly larger than those detected with 2D ultrasonography.

Assessment of placental blood flow between 22 and 34 weeks of gestation by 3D-sonography power Doppler vascular indices.

PURPOSE: To analyze and compare the vascular flow in different parts of the placenta of normal pregnant women between 22 and 34 weeks of gestation through three-dimensional power Doppler ultrasonography (3D power Doppler) vascular indices. METHODS: This is a cross-sectional study involving 55 normal pregnant women with gestational ages between 22 and 34 weeks. The vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were obtained using the virtual organ computer-aided analysis (VOCAL) method both in the region of placental cord insertion and the peripheral region of the placenta. The Wilcoxon test was applied, adopting a significance level of 5% to evaluate possible differences in these indices between study areas. RESULTS: For the three indices examined (VI, FI and VFI), a statistically significant difference was obtained between the insertion of the umbilical cord, designated as the center, and the placental periphery on both the right (p < 0.001 for VI, p = 0.001 for FI and p < 0.001 for VFI) and the left (p < 0.001 for VI, p < 0.001 for FI and p = 0.001 for VFI), taken as the average of the rates obtained in the two peripheries (p < 0.001 for VI, p < 0.001 for FI and p = 0.003 for VFI). Differences were not found when the two peripheral areas were compared or if placenta was anterior or posterior (p > 0.05). CONCLUSION: There is a statistically significant difference between the vascular indices obtained with a 3D power Doppler at different points of the placenta.

Fetal lung volume: comparison by 2D- and 3D-sonography in normal fetuses.

PURPOSE: To compare two-dimensional ultrasonography (2D US) and three-dimensional ultrasonography (3D US) in the assessment of normal fetal lung volume. METHODS: A cross-sectional study was performed involving 50 normal pregnancies at 24-32 weeks' gestation. The following equations were used for lung volume calculation by 2D US: Eq(2D1) = 4.24 + {1.53 x [(area of base of both lungs) x 1/3 (height of right lung)]} and Eq(2D2) = [anteroposterior diameter (X) x transverse diameter (Y) x cranial-caudal diameter (Z) of the right lung x 0.152 + (X') x (Y') x (Z') of the left lung x 0.167]. For 3D US, the virtual organ computer-aided analysis (VOCAL) method was used with a 30 degrees rotation angle and the total lung volume (V3D) was obtained by summing the volumes of each lung. Regression models (R (2)) were devised to assess lung volume evolution over the course of the pregnancy. Pearson's correlation coefficient (r) was used to assess correlation among the techniques, while Friedman's test was used for means comparisons. RESULTS: Strong correlation was observed among the three techniques [V3D vs. Eq(2D2) r = 0.856; V3D vs. Eq(2D1) r = 0.838 and Eq(2D2) vs. Eq(2D1) r = 0.964; all with P < 0.001]. Mean lung volumes were 37.05 +/- 9.67, 29.79 +/- 8.79 and 12.67 +/- 4.12 ml for V3D, Eq(2D1) and Eq(2D2), respectively (P < 0.001). CONCLUSIONS: Strong correlation and significant difference was observed among the three techniques of fetal lung volume assessment in normal fetuses.

Reference range of fetal lung volume by 3D-ultrasonography using the rotational method (VOCAL).

AIM: To determine reference ranges for fetal lung volume by 3-dimensional ultrasonography using the VOCAL (Virtual Organ Computed-aided Analysis) method. METHODS: A longitudinal prospective study was conducted with 61 uncomplicated pregnancies between 24 and 32 weeks of gestation. A separate measurement of both lungs volume was conducted by VOCAL with 30 degrees rotation angle. For each gestational age, an average, standard deviation and maximal and minimal values were established in addition to the percentiles 5, 10, 25, 50, 75 and 90 for right and left lung volume. To evaluate the correlation between lung volume and gestational age, and estimated fetal weight, a polynomial regression with determination coefficient adjustment (R(2)) was used. The intra-observer reproducibility was evaluated by the intraclass correlation coefficient (ICC), whereas the inter-observer reproducibility was evaluated by Cronbach alpha statistic test. RESULTS: The average right lung volume varied from 12.5+/-0.7 cm(3) at the 24(th) week to 31.8 cm(3)+/-1.8 cm(3) at the 32(nd) week. The average left lung volume varied from 9.2+/-0.9 cm(3) at the 24(th) week to 22.0 cm(3)+/-1.6 cm(3) at the 32(nd) week. We observed a strong correlation between right lung volume and gestational age (R(2)=0.975) and estimated fetal weight (R(2)=0.905), as well as between the left lung volume with gestational age (R(2)=0.970) and estimated fetal weight (R(2)=0.908). We observed a good intra-observer reproducibility for the right lung volume (ICC=0.990) and for the left lung volume (ICC=0.986). Similarly, we observed good inter-observer reproducibility for right lung volume (0.975) and left lung volume (0.962). CONCLUSION: Reference range of fetal lung volume by 3D-ultrasonography using the VOCAL method was determined.