OC16.02: Inter-observer reliability of quantitative 3D power Doppler angiography of whole placental vascularity

Abstract

3D power Doppler angiography (3DPDA) allows quantification of blood flow within the placenta. The aim of this study was to investigate the interobserver reproducibility of quantitative 3DPDA as a tool to assess placental vascularity. Subjects were scanned at 12, 16 and 20 weeks gestations with a Voluson 730 Expert. 3DPD data were acquired from the whole placenta and analysed using VOCAL and 9 degree rotation steps. Each image was analysed by three observers who made two measurements in the transverse (B) plane. Interobserver reliability was assessed by two-way mixed intraclass correlation coefficients (ICCs) and Bland–Altman plots estimated the level of agreement between the observers. 52 low risk women were scanned at varying gestations resulting in 30 subjects at each gestation and 90 datasets in total. The ICC for data analysis demonstrated a high level of measurement reliability at each gestation: ICC 0.871, 0.968 and 0.980 for VI; 0.911, 0.924 and 0.958 for FI; 0.981, 0.959 and 0.977 for VFI at 12, 16 and 20 weeks gestation. Bland–Altman plots showed a progressive reduction in the agreement between the observers with increasing gestation. This study demonstrates that 3DPDA data can be measured by different observers to produce a quantitative analysis of whole placental vasculature. Measurements become less reliable as gestation advances.