OBJECTIVE: To evaluate the interobserver reproducibility of vascular indices obtained with three-dimensional power Doppler (3D power Doppler) ultrasonography at the first trimester of gestation. MATERIALS AND METHODS: The present reproducibility study involved 32 healthy pregnant women with 7 to 10 weeks and 6 days of gestation. The VOCAL (Virtual Organ Computer-aided AnaLysis) method was utilized to calculate embryos volume, with a 12° rotational angle. Subsequently, the software automatically displayed three 3D power Doppler vascular indices: vascularization index (VI), flow index (FI) and vascularization and flow index (VFI). In order to calculate the interobserver variability, an investigator performed a second blind measurement of the 32 embryos, and another investigator performed a third blind measurement of the same volumes. The interclass correlation coefficient (ICC) and Bland-Altman plots were utilized for statistical analysis. RESULTS: A good interobserver reproducibility was observed in relation to the three vascular indices. The VI presented ICC = 0.9 and mean difference between measurements = -1.1. For the FI, the ICC was 0.9 and mean difference = -0.5. The VFI presented ICC = 0.9 and mean difference = -1.1. CONCLUSION: The vascular indices, particularly the FI, obtained with 3D power Doppler ultrasonography at the first trimester of gestation demonstrated a high reproducibility.

Keywords: First trimester of gestation, Color Doppler ultrasonography, Reproducibility of results, Three-dimensional imaging

OBJECTIVE: To determine reference values for placental volume at 7 to 10 + 6 weeks of gestation by means of three-dimensional ultrasonography with the XI VOCAL (eXtended Imaging Virtual Organ Computer-aided Analysis) method. MATERIALS AND METHODS: A cross-sectional study was developed with 70 pregnant women at 7 to 10 + 6 weeks of gestation. The XI VOCAL method with ten sequential adjacent planes was utilized in the volume calculations. Means, medians, standard deviation, minimum and maximum values for placental volume were calculated. A scatter plot adjusted by the determination coefficient (R²) was constructed to correlate placental volume and gestational age. RESULTS: Mean placental volume ranged from 4.6 cm³ (2.6-8.6 cm³) to 28.9 cm³ (11.4-66.9 cm³). The placental volume (PV) has shown to be highly correlated with the gestational age (GA) and the best fit equation was [PV = exp(0.582 × GA + 0.063); R² = 0.82]. CONCLUSION: Reference values for placental volume in the first gestational trimester were determined with the XI VOCAL method.

Keywords: Early placental phase, First trimester of pregnancy, Gestational age, Organ volume, Three-dimensional imaging

OBJECTIVE: To evaluate the correlation between the yolk sac volume measured by three-dimensional ultrasonography with gestational age at 7-10 weeks. MATERIALS AND METHODS: A cross-sectional study involving 72 healthy pregnant women at 7th-10th gestational weeks. The multiplanar method with 1.0 mm intervals was utilized. Regression models were constructed to analyze the correlation between yolk sac volume and gestational age, adjusted by the determination coefficient (R²). Mean, median, standard deviation, maximum and minimum values for yolk sac volume were calculated for each gestational age. RESULTS: A poor correlation was observed between yolk sac volume (YSV) and gestational age (GA). The quadratic regression was the model that best expressed this correlation: YSV = 0.9757 - 0.2499 × GA + 0.0172 × GA² (R² = 0.234). Mean yolk sac volume ranged from 0.07 cm³ (0.02-0.11) to 0.20 cm³ (0.02-0.74) between the 7th and 10th weeks (mean, 0.11 cm³, ± 0.10 cm³). CONCLUSION: There was a poor correlation between yolk sac volume and gestational age.

Keywords: Yolk sac, First trimester of pregnancy, Gestational age, Prenatal ultrasonography, Three-dimensional imaging

OBJECTIVE: To assess the reproducibility of fetal thigh and upper arm volumes measurement by threedimensional ultrasonography utilizing the eXtended Imaging Virtual Organ Computer-aided AnaLysis (XI VOCAL) method. MATERIALS AND METHODS: This reproducibility study enrolled 43 pregnant women with healthy singleton pregnancies between 20 and 37 gestational weeks. The XI VOCAL 10 planes was the method utilized for volumetric measurement of the fetal limbs. The calculation of the interobserver reproducibility was based on blind volumetric measurements of fetal thighs and upper-arms performed by two observers in 43 fetuses. Intraclass correlation coefficient (ICC), Bland-Altman plots and paired Student's t-test (p) were utilized in the statistical analysis. RESULTS: A high interobserver reproducibility was observed. For the upper arm volume ICC was 0.996 (confidence interval [CI] 95%: 0.992; 0.998) and mean difference = 0.13 ± 1.29% (95% limits of agreement: -2.54; +2.54%). For the thigh volume, ICC was 0.997 (CI 95%: 0.995; 0.999) and mean difference = 0.24 ± 7.60% (95% limits of agreement: -7.6; +7.6%). CONCLUSION: Fetal thigh and upper arm volumes measured by three-dimensional ultrasonography with the XI VOCAL method presented a high interobserver reproducibility.

Keywords: Reproducibility; Fetal limbs volume; Three-dimensional ultrasonography; XI VOCAL.

Objective: To evaluate the intra- and interobserver reproducibility of three-dimensional power Doppler sonography (3D power Doppler) in the assessment of fetal brain blood flow in the middle cerebral artery territory. Materials and methods: A cross-sectional study was developed with 20 healthy pregnant women between 26 and 34 gestational weeks. The middle cerebral artery territory closest to the transducer was scanned and the blood flow volume was calculated with the method Virtual Organ Computer-aided AnaLysis. The following 3D power Doppler indices were later obtained: vascularization index (VI), flow index (FI) and vascularization-flow index (VFI). The intraclass correlation coefficient (ICC) and Bland-Altman plots were utilized for calculating the intra- and interobserver variability. Results: A good intra- and interobserver agreement was observed, with ICC > 0.90 for all the 3D power Doppler indices: VI [ICC = 0.992 (CI 95%: 0.981–0.997)], FI [ICC = 0.999 (CI 95%: 0.998–0.999)], VFI [ICC = 0.995 (CI 95%: 0.987–0.998)]. Interobserver reproducibility: VI [ICC = 0.988 (CI 95%: 0.970–0.995)], FI [ICC = 0.999 (CI 95%: 0.997– 1.000)], VFI [ICC = 0.994 (CI 95%: 0.994–0.998)]. Conclusion: 3D power Doppler has shown to be a practical and easy method in the assessment of fetal brain blood flow, with good intra- and interobserver reproducibility. The FI presented the best intra- and interobserver agreement.

Keywords: Reproducibility of results; Prenatal ultrasonography; Fetal brain flow; Power Doppler; Threedimensional sonography.