Figure 4: Top-down view on a left atrium and associated contrast-enhanced projections showing a correct registration (a) and two misregistrations (b) and (c). When looking at the contrasted pixels on each detector independently, all LA positions seem to be feasible. Considering the LA position in (b), the area, which can contain contrast agent according to the combination of both detectors, is partially outside the LA. For the CADE, however, only contrast agent inside the LA is considered. So the registration in (b) gives rise to contrasted pixels on the A-plane detector that cannot be explained by the CADE. This will result in a low CADE value and indicate misregistration. There exist, however, also misregistrations that can lead to a consistent CADE as shown in (c). This is why a combination of CADE and edge-based methods yields improved results.