Real-time ultrafast ultrasound imaging of human placental blood flow

The human placenta plays an important role in fetal development because it is the location for the maternal-fetal exchange of blood that carries nutrients, oxygen, and wastes. Placental abnormalities are associated with adverse outcomes, including preeclampsia and intrauterine growth restriction, both of which have been linked to aberrant placental hemodynamics. However, current clinical ultrasound techniques face challenges in imaging slow flow in small vessels during the first and second trimesters due to their limited sensitivity. Ultrafast ultrasound imaging offers higher sensitivity to blood flow using long ensemble acquisitions and spatiotemporal filtering but has higher computational demands, limiting its real-time application in clinical placental imaging. To provide real-time sensitive placental blood flow imaging, we developed a real-time ultrafast flow imaging system for placental blood flow using GPU-based beamforming and spatiotemporal filtering on a Verasonics Vantage NXT 256 research scanner. In an in vivo human placental study, the system achieved seven to nine frames per second using an ensemble length of 32 and spatiotemporal filtering. This enabled real-time visualization of millimeter-scale vessels in the myometrium and placenta, demonstrating the potential of GPU-accelerated ultrafast flow imaging as a sensitive technique for clinical placental hemodynamic assessment and early detection of vascular abnormalities in pregnancy.