Advanced subtraction angiography: mask selection and image registration

Conventional DSA in cardioangiography is hampered by the rapid and irregular heart movement. Thus, extended subtraction artefacts occur due to the bad congruence of corresponding structures. A native sequence of one heart cycle serves as a pool of mask images. The ECG signal is used to find the corresponding mask image. An image registration algorithm was developed to estimate displacements in numerous (>6000) local image regions. The resulting motion pattern is used to compute a new warped image with maximum congruence. This calculated image becomes the new mask in the subsequent subtraction. The algorithm works fully automatically and does not need any interaction like the demarcation of landmarks. Better assessment of the coronary vessels and the ventricle with reduced artefacts is the diagnostic benefit of this image enhancement