In-vitro ultrasound evaluation of flow in a saccular aneurysm treated with a stent
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The purpose of this thesis is to evaluate blood flow and density inside intravascular stenting in the straight-vessel and curved-vessel aneurysm models and to investigate the effect of treatment with intravascular stenting. A peristaltic pump makes a constant flow with a dampener produced flow of blood-mimicking fluid through vessel aneurysm phantoms made of silicon elastomer. Ultrasound images were acquired using a DIASONIC ULTRASOUND SYNERGY TM system. The fluid velocity inside a Region of Interest (ROI) is measured from the D-mode (Doppler) using a 10 MHz linear transducer. The quantity of red-blood-cell-simulating moving particles inside the ROI is observed from A-mode (Angio or Power Doppler) using a 10 MHz linear transducer. To overcome the angular dependence of US acquisition, three different sections are applied for observing. Those sections give a 2D image, blood-cell velocity, and quantity of moving particles which have the same vector components within each section. In-vitro flow velocity measurement is focused on finding velocity components to evaluate the flow behavior within the aneurysms and examine hemodynamic implications of several treatments using flow modulating devices such as a standard, stent and an asymmetric vascular stent with a patch, applied to two types of saccular aneurysms. Those treatments may reduce the risk of rupture by reducing flow inside aneurysm. Power Doppler curve provides a means for comparing treated and untreated aneurysms using the intensity distribution curve related to the quantity of moving particles pressing in the aneurysm wall parallel with the transducer beam direction.