Detailed flow visualization in fetal and neonatal hearts using 2-D speckle tracking
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Two-dimensional blood speckle tracking has shown promise for measuring the complex flow patterns in neonatal hearts when based on linear array and high-frame-rate plane wave imaging. For phased array pediatric imaging, additional challenges emerge due to the reduced lateral bandwidth and increased imaging depth and field-of-view. In this work, a clinically approved setup with pediatric phased array probes and unfocused pulses was used to investigate the potential of blood speckle tracking to acquire 2-D vector velocity maps for neonates, infants and children with congenital heart disease.Promising results were observed for depths <; 10 cm, where complex cardiac flow patterns could be visualized. However, due to the small aperture available, diffraction effects could be observed. Further, as the depth dependent lateral resolution and loss in signal-to-noise ratio degrades tracking results for increasing depths, a larger feasibility study is needed to establish clinical viability. Vector velocity maps were also obtained from fetal examinations with the phased array setup as well as with a diverging beam setup on a research scanner, where detailed secondary flows such as the vortex formations in the ventricles of the fetal heart could be observed.