P782Flow speckle tracking for detailed visualization of flow patterns in neonates with congenital heart defects

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Purpose: There is a close relationship between the intraventricular blood flow pattern and ventricular function. MR velocity mapping, Doppler- and contrast-echocardiography have been used to evaluate flow dynamics, but has limitations or is not well suited in small children. We describe an angle-independent flow imaging technique based on blood speckle tracking to investigate flow patterns in congenital heart disease.Methods: We used a custom colour flow imaging acquisition based on plane wave imaging (unfocused) with 16 image lines generated in parallel for each emitted pulse. This was done to increase overall image frame rate and process near-instantaneous snapshots of blood. The movement of blood speckle was quantified in 2-D images using established pattern-matching techniques. Linear array transducers (9 and 11 Mhz) were used to avoid image artefacts when utilizing a high number of parallel beams.Results: 10 neonates (2.1-5.5 kg) with different congenital heart defects were examined with flow tracking in addition to standard echocardiography. 2D- flow patterns were superimposed on the colour flow images. Tracking revealed detailed additional flow information, and removed the need for angle-correction. In the example figures, flow is visualized using streamlines. To the left there is apical vortex flow in a dilated, hypertrophic left ventricle and to the right there is right ventricular vortex flow and shunt flow in an inlet ventricular septal defect.Conclusions: Flow speckle tracking may be well suited to image complex flow patterns in neonates. To detect vortex flow is important because it may influence stroke output and efficiency of the ventricles. However, imaging with this technique is currently limited to linear array transducers which may limit penetration.

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