LAA Morphological and Functional Parameter Assessment
The morphology of the LAA was assessed from 3D LGE images using particle-based modeling (PBM) for statistical shape analysis (SSA). Briefly, after contouring and segmentation by trained observers, we created a three-dimensional reconstruction of the LAA. SSA using particle-based modeling was performed on the LAA reconstruction to define the shape class. For LAA ostium measurements, we used three planes on the CMR to define the ostium and estimate its maximal diameter, minimal diameter, circumference, and surface area. The ostium of the LAA was first defined on the transversal image by the plane that connected between the base of the Coumadin ridge and the proximal left circumflex artery. The cross-section of the LAA ostium was created from orthogonal projections in the coronal plane. The maximum and minimum LAA ostium diameters were measured from the sagittal image. The circumference and surface area were then calculated and provided by the software. Figure 1 shows the procedural steps for registration of the pre- and post-ablation LGE-MRI images to ensure spatial alignment as well as for measurement of the LAA ostium.