Dahl lab awarded NICHD R01 grant for Placental Flow Imaging

The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) has recently awarded our lab an R01 grant entitled "High Sensitivity Flow Imaging of the Human Placenta" to develop coherent flow power Doppler (CFPD) and other coherent flow imaging techniques for the application in human placental imaging.  The grant is part of the Human Placental Project, lead by Dr. David Weinberg, Ph.D., at the National Institutes of Health.

In this research, we are developing novel technologies to help clinicians assess spiral artery remodeling of the placenta vasculature.  The spiral arteries are key to the health and development of both the placenta and the fetus, and generally, these arteries widen in the area where they feed into the intervillous space (i.e. the space where the mother's blood exchanges nutrients, gases, and wastes with the fetal blood).  Spiral arteries are very small, on the order of 0.2 to 0.5 millimeters prior to widening at the intervillous space.  As the placenta develops, the area of widening grows so that the blood entering the intervillous space slows down; if this remodeling process does not occur, the high ejection of blood into the intervillous space can reduce the development of intervillous structures, leading to prenatal problems such as preeclampsia and intrauterine growth restriction.

Our work aims to develop a high sensitivity flow imaging technique that will allow clinicians to detect and visualize the slow flow of blood in the spiral arteries, since current ultrasound flow imaging technology is insufficient for these small vessels or their slow flow.  Using a method called short-lag spatial coherence (SLSC) beamforming, which detects the spatial coherence of the ultrasound signals rather than their echo amplitude, we are better able to differentiate ultrasound signals reflecting from blood from those signals that are noise.  Applying this concept to ultrasound flow detection techniques, we have developed a method called coherent flow power Doppler (CFPD) that is highly sensitive to the slow blood flow signal, and we are developing further techniques that will improve the estimates of flow velocity.  This will allow clinicians to observe the spiral arteries and their remodeling process early in the development of the placenta. 

CFPD (left) and PD (right) images of 11.5 mm/s flow in the phantom experiments with ensemble lengths of (a) 3, (b) 5, (c) 11, and (d) 13 acquisitions. The scale bar on the right corner indicates 4 mm, and the colorbar has units of dB. The dynamic range is 30 dB for all images. The figure CFPD images show better SNR and lower background noise than PD. The PD image suffer from higher background noise at deeper depth.