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Session: Vascular I
Session starts: Thursday 26 January, 14:30
Presentation starts: 14:30
Room: Room 559

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Larissa Jansen (Photoacoustics and Ultrasound Laboratory Eindhoven )
Hans-Martin Schwab (Photoacoustics and Ultrasound Laboratory )
Richard Lopata (Photoacoustics and Ultrasound Laboratory )

Abstract:
Imaging abdominal aortic aneurysms (AAAs) using conventional 3D ultrasound (US) imaging is challenging, because the field of view and temporal resolution are limited. Furthermore, due to the physics of US, the AAA wall is best visible in regions where the angle of incidence of the US beam with respect to the vessel surface is small (< 20°). Acquisition from multiple perspectives can help to increase the field of view, increase wall visibility, and improve lateral resolution. These approaches require adequate spatial and temporal registration, and image fusion. Hence it would be more convenient to have a large footprint probe or ultimately a flexible patch that can be attached to the abdomen. However, such large aperture probes are not yet available. Therefore, in this study we propose to use a multi-aperture high frame rate approach for enhanced functional imaging of AAAs. An AAA mimicking phantom was made from polyvinyl alcohol by using a custom mould. This phantom was attached to a circulatory mock-loop setup that mimics the circulatory system. A flow pump was used to pump water into the phantom with a predefined pulsatile flow pattern. A bistatic interleaved high frame rate sparse aperture transmit-receive sequence was implemented for two 1024¬-element Vermon matrix probes, which were each connected to a vantage-256 Verasonics US system. Using a translation stage, data was gathered with the two probes at different positions along the vessel length and with different probe orientations. Imaging was performed in a high-quality mode and high frame rate mode by changing the number of compound angles. After spatial and temporal registration of the multi-aperture data, image reconstruction was performed to obtain a large 3D + time dataset suitable for functional imaging. With the multi-aperture approach proposed, large field of view high frame rate 3D data of AAA phantoms were obtained, from which a more complete AAA geometry can be assessed. Furthermore, the different imaging modes allow for various applications such as geometry assessment, strain imaging and flow measurements. Future work involves imaging patient specific aneurysm geometries and improve imaging of the bifurcation towards the iliac artery.