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Session: Poster session II
Session starts: Thursday 24 January, 16:00

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Peiran Chen (Eindhoven University of Technology)
Ruud van Sloun (Eindhoven University of Technology)
Simona Turco (Eindhoven University of Technology)
Hessel Wijkstra (Eindhoven University of Technology)
Patrick Houthuizen (Catharina Hospital)
Massimo Mischi (Eindhoven University of Technology)

Abstract:
Heart-failure is one of the leading causes of death world-wide. In heart-failure, the main pumping chambers of the heart may become stiff, resulting in inefficient blood pumping. A clinically-proven treatment option for heart failure is cardiac resynchronization therapy (CRT), which aims at improving pumping efficiency. Functional impairment of the left ventricle (LV) commonly occurs already at the early stage in the development of heart disease. Since blood flow patterns are strongly associated with the ventricular function, cardiac diagnostics may benefit from flow-pattern analysis. Several blood flow-pattern visualization tools have been proposed that require ultrafast ultrasound acquisitions, while techniques that can deal with low frame rates are still lacking, especially for the emerging 3D ultrasound, for which the volume rate is intrinsically low. To overcome this limitation, we propose a novel technique for the estimation of LV blood velocity and relative-pressure fields from 2D dynamic contrast-enhanced ultrasound (DCE-US) at low frame rates. Different from other techniques, our method is based on the time-delays between time-intensity curves measured from a set of neighboring pixels in the DCE-US video. Using Navier-Stokes equation, we regularize the obtained velocity fields and derive relative-pressure estimates. Blood flow patterns are characterized in terms of their vorticity, changes in relative pressure (dp/dt) in the LV outflow tract, and viscous energy loss, as these reflect the ejection efficiency. Since the goal of CRT is improving pumping efficiency, we evaluated the proposed method on 18 patients (9 responders and 9 non-responders) who underwent CRT. After CRT, the responder group evidenced a significant (p<0.05) increase in vorticity and peak dp/dt, and a non-significant decrease in viscous energy loss. No significant difference was found in the non-responder group. Relative feature variation before and after CRT evidenced a significant difference (p<0.01) between responders and non-responders for all the features. In the future, the feasibility of the method for 3D DCE-US will be investigated.