Figure 1: Three different contrast agent injections. The left column shows an uncontrasted frame, the middle column shows a contrasted frame of the sequence, and the rightmost column shows a subtraction of both images. The manually established ground-truth position of the left atrium is overlaid with red. The LA in image (c) appears only faintly contrasted and the CA just flows into the ventricle. On the other hand, image (f) shows disturbing motion artifacts caused by leads and wires associated with an implanted device. In image (i), the contrast agent is injected into a pulmonary vein and catheter motion artifacts are visible. While the spine in the center of this image vanishes, soft-tissue motion artifacts related to the lungs are visible at the left and right border, respectively.