(a)
(b)
Figure 8: Distribution of the errors within each sequence. While there is no significant difference for initial injections (a), performs significantly better than for subsequent injections (b). Subsequent contrast injections are characterized by a smaller amount of contrast and the presence of more catheters making registration more difficult. Example images of sequence 1 are shown in Figures 2 and 3; example images of sequence 2 are shown in Figure 1(a). Here, contrast agent is very faint and in some frames contrasted is already ejected into the left ventricle. Sequence 5 is shown in Figure 1(d). In this case, got confused by edges caused by motion artifacts.