An invariant approach for image registration in digital subtraction angiography

In modern medicine, digital subtraction angiography is a powerful technique for the visualization of blood vessels in a sequence of X-ray images. A serious problem encountered in this technique is misregistration of images due to patient motion. The resulting artifacts which arise from the misalignment of successive images in the sequence frequently reduce the diagnostic value of the images. In this paper, a new approach to the registration of digital angiographic image sequences is proposed. It is based on local similarity detection by means of template matching according to a combined invariants-based similarity measure and on thin-plate spline image warping. This technique is fully automatic and very efficient to correct for patient motion artifacts. The proposed algorithm for this technique has been successfully applied to register several clinical data sets including coronary applications. It works perfectly well for both slow and sudden motions and is both effective and fast.