Figure 6: Top-down view on a left atrium with a contrasted pulmonary vein. The gray region denotes the area which may contain contrast agent based on the contrast agent observed in the 2D images. If the number of contrasted voxels in the volume was to be optimized, the optimization process would find a transformation such that as much of the potentially contrasted region as possible was included within the LA causing a registration bias towards larger LA regions.