P. Maday, R. Brosig, J. Endres, M. Kowarschik, N. Navab Blood flow quantification using optical flow methods in a body fitted coordinate system SPIE Medical Imaging, San Diego, CA, USA, Feb 19-23 2014. (bib)
	In this paper a blood flow quantification method that is based on a physically motivated 2D flow estimation algorithm is outlined. It yields accurate time varying volumetric flow rate measurements based on digital subtraction angiography (DSA) image sequences, with robustness to significant inter-frame displacements. Based on the 2D flow fields and a 3D vessel segmentation the time varying volumetric flow rate is estimated. The novelty of the approach lies in the use of a vessel aligned coordinate system for problem formulation. The coordinate functions are generated using the Schwarz-Christoffelcite{driscoll2002schwarz} (SC) map that yields a solution with coordinate lines aligned with the flow streamlines. The solution of the finite difference problem only requires slight modifications compared to the regular grid case. The use of vessel aligned coordinates enables the easy and accurate handling of boundary conditions in the irregular domain of a vessel lumen. Unlike traditional coarse to fine approaches we use an anisotropic scaling strategy in the vessel aligned coordinates that enables the estimation of flows with larger inter frame displacements. The evaluation of our method is based on highly relistic synthetic datasets for a number of cases. Performance measures are obtained with varying flow velocities and acquisition rates
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