Reproducibility of placental volume and vasculature indices obtained by 3-Dimensional power Doppler sonography

Objective: The purpose of this study was to evaluate the reproducibility of 3-dimensional (3D) power Doppler assessment of placental volumes and vascularization before adopting these in routine evaluation of normal and complicated pregnancies. Methods: A prospective study was performed on 30 normal singleton pregnancies from 11 to 14 weeks. To evaluate placental vascularization, 3D power Doppler sonography was applied to obtain a placental volume, and the volume acquired was analyzed using virtual organ computer-aided analysis. Two consecutive measurements were taken from each patient by two observers blinded to each other's and the individual's previous measurement. This yielded a total of 60 data set pairs. The placental volume, vascularization index, flow index, and vascularization- flow index (VFI) were calculated. Normal distribution of the data was confirmed with the Kolmogorov-Smirnov test. Intraobserver and interobserver correlations were evaluated. Bland-Altman plots and statistics were used to compare the 95% limits of agreement between measurements. Results: All 3D power Doppler placental volumes and vascular indices showed intraobserver correlations of 0.80 or higher. Similar excellent interobserver correlations were seen for all indices with the exception of the VFI, which showed a lower but acceptable correlation. The Bland-Altman analyses indicated good reproducibility of the evaluated placental indices. Conclusions: Our findings provide validation of the technique, showing good reproducibility of the 3D power Doppler parameters when applied to studies of the placental volume and vascular tree.