Image registration for digital subtraction angiography

In clinical practice, Digital Subtraction Angiography (DSA) is a powerful t echnique for the visualization of blood vessels in the human body. The diag nostic relevance of the images is often reduced by artifacts which arise fr om the misalignment of successive images in the sequence, due to patient mo tion. In order to improve the quality of the subtraction images, several re gistration techniques have been proposed. However, because of the required computation times, it has never led to algorithms that are fast enough so a s to be acceptable for integration in clinical applications. In this paper, a new approach to the registration of digital angiographic images is propo sed. It involves an edge-based selection of control points for which the di splacement is computed by means of template matching, and from which the co mplete displacement vector field is constructed by means of interpolation. The final warping of the images according to the calculated displacement ve ctor field is performed real-time by graphics hardware. Experimental result s with several clinical data sets show that the proposed algorithm is both effective and very fast.